Science Makes Sense-Week 44:Chemistry and Social Justice-The story of Deepwater Horizon and BP:the legacy of oil

September 13, 2016

I look at Hillsborough Bay in Florida to see a placid water body and the seagulls screeching while the brown pelicans sit on the wooden pole perches. And I wonder…… if they could talk to me would they tell me what really happened to their families and the humans around them six years ago during that oil rig explosion?  What really lurks beneath the calm blue waters?

The Gulf of Mexico is known for its rich variety of flora and fauna and also a long coral reef.  Pulley Ridge, 150 miles west of Cape Sable, Florida,has the deepest coral reef in the U.S.  There is another coral reef 110 miles south of the Texas- Loiusiana border.  The whooping crane, the peregrine falcon,piping plover, brown pelican and even the bald eagle make their home here in the gulf.  The shrimp and  fish industry supplies most of our sea food.   There are also a variety of endangered species of whales found in these waters.(Ref.1)  The area is at the same time, also rich in fossil fuel deposits under water.  Off- shore oil rigs have become the way to keep drilling for more oil by those not willing to look for alternative/green sources for our energy needs.

Deepwater Horizon was the name of an ultra-deepwater semi-submersible off-shore oil rig owned by a company called Transocean and leased to BP from 2001.  On 20th April, 2010, while drilling at the Macondo Prospect, an explosion on the rig caused by a blowout killed 11 crew members, ignited a fireball visible from 40 miles away.  The resulting fire could not be extinguished and in the process of doing that, the rig sank, leaving the well gushing and causing the biggest oil spill in U.S. waters.(Ref.2)

Drilling for oil, especially oil that is deep under water, is considered an acrobatic feat.  The crew drills the pipe to hit the oil level and the deeper one goes, the greater is the pressure of oil and mostly methane gas.  The comparison is made with a giant bag of popcorn taken out of the microwave ready to be opened buried under 5,000 feet of ocean and 13,500 feet of earth.  Instead of ripping the bag open, you insert an 18,500- foot straw, actually a pipe and then place a thumb over the straw, so the contents do not explode.  The air in the bag contains methane, the popcorn is the crude oil while the thumb is the cement used to seal the hole. (Ref.3)  Managing the pressure at such depths to bring up the oil and gas mixture in a controlled manner is called well- control. Problems managing the pressures is called a kick , whereas, loss of well- control is called a blowout.(Ref.3)

Why did the blowout occur?  It was later learned that there had been no regular check-ups on backup switches to close the flow of  gas in case of any mal functions.  The oil rig was equipped with visual and auditory alarms to shut off gas which was methane,CH4. Unfortunately, since these alarms make too much noise in the early morning  they were deliberately shut off!(Ref.4)

Following the blowout, the oil kept gushing and BP tried to deal with it by the addition of a dispersant called Corexit so the oil could be dispersed over a larger area.(Ref.5) 

Having somewhat understood the way this disaster occurred and the steps taken by BP, let us look at the chemistry of the chemicals present in the oil rigs during the blowout and later the effects on the species living in and around the gulf area. The burning of the oil rig was due to the methane gas, CH4 that was present which is highly inflammable.  The release of such a large amount of methane gas also leads to the depletion of oxygen in the water and the consequent acidification of the water.   This results in the killing of marine life and all other life dependent on it.  In addition, crude oil contains VOCs which are volatile organic compounds like benzene, toluene and xylene.  Benzene is a known human carcinogen, while toluene and xylene cause nausea, vomiting and fatigue to name a few problems that can ultimately lead to long term health hazards like cancer and birth defects.   Crude oil also contains mercury, lead that are known toxins.  Polycyclic hydrocarbons, also known as PAHs are present in crude oil which contains over a hundred different forms of these hydrocarbons.  Again, they are very toxic and cause cancers in mammals and humans.  When crude oil sits on water or shore, its harmful effects can be carried by the wind and air as a toxic aerosol.  When oil coats the body of the animals in the water, including many birds, it limits its ability to feed, move or even reproduce.  It also harms the external and internal organs of the animals adversely.  In addition, the roots of plants and trees along the marshy grasslands near the gulf shore are killed by the presence of oil.  These plants and trees actually protect those coastal regions to a certain extent from strong hurricanes.  Add to that the immense loss in tourism due to oil washing up on the shores of the sandy beaches dotted all over this area.(Ref.6)

To try to counter the presence of oil, as already noted, BP added the dispersant, Corexit.  This may have hidden the presence of oil to observers, but the dispersing only spread it over a larger area.  The excessive amounts used were unprecedented and its effects are well documented 5 years after the spill in a GAP (Government Accountability Project)report.  More than a dozen whistle blowers were interviewed by GAP.  Here is a summary of the first-hand effect of the devastating impacts of the oil in the water and the subsequent Corexit usage.  The witnesses range from cleanup workers, fishermen, scientists, residents and a physician.

  1. BP syndrome: all GAP witnesses experienced severe health problems, starting with blood in urine, heart palpitations, skin lesions and skin burning leading to kidney and liver damage and respiratory and nervous system damage.
  2. Interviewees were very concerned about long-term results including reproductive damage, endocrine disruption and cancer.
  3. Blood test results revealed high levels of chemical exposure to Corexit and oil; the chemicals here are known to be carcinogens.
  4. Ecological problems: there is evidence of oil and oil debris even after the cleanup was done.  The oil-Corexit mixture has coated the Gulf seafloor and permeated the rich ecological web leading to barren seafloor, widespread damage to the coral reefs.
  5. Majority of fishermen reported that their fish/ sea species had deformities and their catch had decreased substantially after the spill in 2010.(Ref.7)

In conclusion, I have to state that this is a much bigger problem than just BP’s bottom line on profits and gross negligence.  So long as we are dependent on big oil and continue to obtain our energy resources from the fossil fuel industry,we shall go along this slippery slope and destroy our fragile ecosystem and ultimately our lovely planet.

Activities for Middle School Teachers:

VOCs are present in all oil fields.  Students can look at VOCs and its usage in other industries besides oil rigs, e.g., in the paint/ varnish industry.  What safeguards are taken by workers when working with these aromatic compounds?

Students can do simple experiments adding oil to water and seeing how much detergent needs to be added to disperse it. What happens to the oil?  How does a detergent help disperse grease? (Instructor can introduce terms like hydrophilic and hydrophobic here, studying the structures of oil and detergents.) As the ratio of oil to water increases is there a critical point where the detergent is not effective? What other side effects would occur if the detergent is strong like Corexit?

Nuggets of Information:

The Gulf of Mexico has the most methane-rich production area and is also one of the most dangerous places to drill.(Ref.3)

Gas kicks are routine during oil drilling; even blowouts happen a lot of times.  From 1993-1998 there were 11 blowouts, and from 1999-2004 there were 20 blowouts in the Gulf of Mexico!(Ref.3)

Kemp’s Ridley Turtles were ready to be removed from the endangered species list, but thanks to the Deepwater Horizon disaster, they now are facing near extinction.(Ref.8)

Oil kills marshland directly and also poisons the complex mixture of algae, microbes in the soil.(Ref.8)

40% of the Gulf of Mexico’s federal waters were closed to fishing by early June 2010.(Ref.8)

Louisiana is the largest producer of shrimp and oysters in the nation and the second largest producer of crabs.  As a result of this oil rig disaster, the cost to the Louisiana fishing industry could total 2.5 billion dollars.(Ref.9)

A movie about this disaster called “Deepwater Horizon” is set to release soon.(Ref.10)

References:

1.Juhasz,Antonia, Black Tide,p.138 (John Wiley and Sons,2011)

2.deepwaterhorizon.com

3.Juhasz,Antonia, Black Tide,pp.10 ,11(John Wiley and Sons,2011)

4.Juhasz,Antonia, Black Tide,p.24 (John Wiley and Sons,2011)

5.Juhasz,Antonia, Black Tide,p.100 (John Wiley and Sons,2011)

6.Juhasz,Antonia, Black Tide,p.90 (John Wiley and Sons,2011)

7.whistleblower.org/gulftruth

8.Juhasz,Antonia, Black Tide,pp.143-5 (John Wiley and Sons,2011)

9.Juhasz,Antonia, Black Tide,p.163 (John Wiley and Sons,2011)

10.m.imdb.com/title/tt1860357/

Science Makes Sense-Week43:Organic Chemistry-Starches, sugars, cellulose

September 7, 2016

As children, we were fascinated by travel and far-off destinations. We would implore our parents to take a trip around the world and the answer would invariably be:” We cannot afford it, money does not grow on trees!”  If I had studied science then, I could have smartly retorted,” Oh but it does! Money is made from paper and paper comes from trees!”

Starch and cellulose molecules are polysaccharides,which literally means ‘many sugars’. (Ref.1). Cellulose is a long chain of linked sugar molecules that gives wood its strength and is the main component of plant cell walls and the starting point for textiles and paper.(Ref.2)  Cellulose is a poly saccharide polymer with many glucose mono saccharide units (Ref.3) and so is starch.   What is the difference?  Now each glucose unit is joined by acetal linkages.   These acetal linkages are actually an oxygen atom, connecting each glucose unit, left after a reaction between an alcohol group,-OH,with an aldehyde ,CH=O group where the water molecule is removed. (Ref.1)  In cellulose the acetal linkages are beta linkages (acetal group in the upper position) while in starch these are alpha linkages (acetal group in the lower position).  This interesting variation in acetal linkages between starch and cellulose  results in major difference in digestibility in humans.  Humans cannot digest cellulose since they lack the enzymes needed to break the beta linkages, while they can easily  digest starch.  Animals such as cows,sheep, goats and termites  have symbiotic bacteria in their intestinal tract that breakdown cellulose.(Ref.3)

The structure of cellulose and starch vary because of the different acetal linkages as well.  The angles in the beta linkages makes the polysaccharide cellulose a linear chain.  Meanwhile the angles of the alpha acetal linkages in starch form a spiral like a coiled spring.(Ref.3)

These polysaccharides are abundant in nature and their main function is energy storage and are the components of cell walls. They are called mono-polymers because they yield only one type of monosaccharide,namely glucose, after hydrolysis. Hetero-polymers also exist in nature (namely those polysaccharides which yield many kinds of mono-saccharides upon hydrolysis) and include gum, pectin.(Ref.4)  

Polysaccharides are not sweet-tasting like mono or disaccharides. They are non- reducing carbohydrates and do not undergo mutarotation.(Ref.4)  What is mutarotation?  A monosaccharide like D- glucose has two stereo isomers that can co-exist because of change in specific rotation of the chiral compound (a compound that does not superimpose on its mirror image).  The two isomers are called alpha D-glucose and beta D- glucose respectively.  Both are cyclic compounds with one acetal group, 5 carbons, 5 hydroxyl groups (-OH).   In the alpha form, one of the -OH is in the lower position whereas in the beta form it is in the upper position.(Ref.5)

Uses of sugars, cellulose and starch:  these mono/ di and polysaccharides can also be broadly classified as carbohydrates, sources of energy.  Green plants manufacture sugars and most of it is used for plant metabolism and very little accumulates.  However many vegetables and trees are sources of commercial sugar.(SeeNuggets)  Cellulose is a complex carbohydrate and cotton, pure cellulose, is the starting point for artificial fibers.  When wood, also cellulose, is treated with concentrated acids and alkalis, the bond between wood fibers and the lignin ( which holds them together tightly) is broken.  These can be reorganized to form paper.  Treated with more chemicals this can lead to the production of artificial fibers and cellulose plastics.  If you further break it down to the individual elements of carbon, C, hydrogen,H, and oxygen,O, (which is the fundamental elements in cellulose) these elements  can be recombined to form wood sugar, yeast and alcohol.  These are the raw materials for many industrial products.(Ref.6)

From time immemorial, we humans have depended on starch, cellulose and sugar for our energy intake, today we have broadened its usage considerably.

Activities for Middle School Teachers:

Construct molecules with acetal or hydroxyl linkages.  What changes in structures are observed with alpha or beta linkages? Where do you see stereo isomerism? Why or why not? (Remember the lack of rotation in the poly saccharides like cellulose and starch)

Students will look at the timeline for cotton production in the U.S. and other countries.  What was the impact of slavery on cotton productions?  How long did the production of cotton depend on African American labor even after slavery was dismantled?  As students study the structure of cellulose, let them study the history of  cotton production here in the US.

Look at potato, a common starch source for the western world. How were the Irish affected by the potato blight?  How did it change the demographics in the U.S.?

Nuggets of Information:

Cotton is the purest form of cellulose.  In the laboratory, ashless filter paper is, for all practical purposes,a source of pure cellulose.(Ref.2) 

Sucrose or table sugar is the most familiar disaccharide made by linking fructose and glucose.(Ref.2)

The length of the cellulose chain varies greatly: a few 100 sugar units in wood pulp to 6000 units  for cotton! (Ref.3)

Linking just two sugars produces a disaccharide called cellobiose, whereas cellulose is a polysaccharide produced by linking additional sugars in the same way.(Ref.3)

Storage sugars are found in roots of plants like beets, carrots and in stems of plants like sugar cane, sorghum and in flowers such as palm sugar and sugar maple.(Ref.6)

Maize/Indian corn is the source of 80% of the starch made in the U.S., while Europe is the principal producer of potato starch.(Ref.6)

References:

1.education.seattlepi.com/chemical-composition-starch

2.antoine.frostburg.edu/chem/Sienese/101/consumer/far/what-is-cellulose

3. chemistryelmhurst.edu/vchembook/547cellulose.html

4.chemwiki.ucdavis.edu/Textbook_Maps/Organic_Chemistry_Textbook_html

5. ochempal.org/index.php/alphabetical/m-n/mutarotation/

6.faculty.ucr.edu ( look for sugars,starch and cellulose)

 

Science Makes Sense: Week 42-Metalloids and Semi-conductors

August 29, 2016

Even before visiting the west coast of the United States, many of us have heard of Silicon Valley which is a little south of San Francisco.  This is where the electronics/Computer industry boom occurred.  Why is Silicon attached to the name?   This element, besides being famous for creating glass centuries ago is the 20th and 21st century metalloid used in the semi-conductor industry.

Metalloids are considered to be neither metals nor non-metals.  ( As you already know, metals are willing to give up electrons to become cations, while non-metals are eager to take in electrons to become anions.)  Or they could be considered to be both a metal and a non-metal.  The metalloids are on the right side of the Periodic Table, closer to where the non-metals are positioned.  The metalloids  form a stairs-like configuration and include, Boron, B, silcon, Si, germanium,Ge, arsenic,As, antimony, Sb, tellurium,Te, and polonium, Po.(Ref.1)

These metalloids are usually brittle, shiny and behave like electrical insulators at room temperature.  When heated , they behave like conductors.  They also behave like conductors when small quantities of impurities are introduced or ‘doped’ into the crystalline lattice structure of metals.  Metalloids have the electronic structure in between that of the nearly empty outer shell of typical metals and the nearly filled shells of non-metals.  They have enough empty electronic orbitals into which electrons can be moved to conduct an electric current.  Their chemical properties  are also in between electropositive and electronegative atoms.  In physics one would call these elements semi-conductors.(Ref.2)  Semiconductors  have electrical resistance in between that of a conductor and an insulator. (Ref.3)  The electro negativity and ionization energies of metalloids lie between those of metals and non-metals.(Ref.4)

To understand semi-conductors, let us step back a little to look at the history of radios and transistors.  A radio  is a device that needs electricity and needs to be plugged while a transistor runs on batteries and could be carried around, the’boom box’, as it was called.  The latter relies on semi-conductor technology.  The ‘transistor’ is short for ‘transfer resistance’, and is made up of semiconductors and is a part/component used to regulate the amount of current/voltage  used to amplify/modulate/switch on or off an electronic signal.(Ref. 3)  This is the primary building block for an electronic chip, including the CPO ( central processing unit) in every computer we use.

Let us elaborate.  Silicon changes its behavior to a conductor when small amounts of impurities are added to it.

N-type: small quantities of phosphorus, P, or arsenic, As, are added to pure crystals of Si.  P and As have 5 outermost shell electrons, whereas Si has only 4.  The extra electron is free to move around and causes the silicon to turn into a conductor.( Ref.5)

P- type:when boron,B, or gallium, Ga, is added to Si,these atoms have only 3 electrons in their outermost shell. This results in’holes’or positive charges and once again causes a flow of current in the silicon crystal.   A minute amount or P or N- type doping in silicon causes an insulator into a viable conductor; hence the name semi-conductor.(Ref.5)

One can see that the P or N- type doping, evolved to the P-N-P and N-P-N sandwiches leading to transistors and electronic chips through micro-processors.( See Nuggets)  After the invention of transistors in 1954, the field of electronics has evolved dramatically to where we are now, using smart phones and watches like we always had them, handling all our needs from these devices.  Metalloids have been responsible for these amazing changes in our electronic lives.  Yet there are other significant uses for these metalloids that need to be mentioned as well.  Here are some selected few uses that is by no means complete.

Boron has been used to make high resistance glass, especially to thermal shock, control rods in nuclear reactors, also in strong magnets, in CD and DVD players and MRI machines.  Silicon has been used to make high temperature waxes, alloys of Si have been used to make car parts, also in breast implants and contact lenses.  Germanium has a high refractive index and has been used in wide-angle camera lenses and as a catalyst in polymerization reactions, fiber optics as well as in the treatment of AIDS.  Arsenic as an isotope has been used in locating tumors.  It is also used as an insecticide, fungicide and in the treatment of cancer.  Alloys of antimony have been used to make bullets, in acid batteries. In addition Sb has been used as a catalyst in polymer production.  Tellurium has been used to tint glass, cast in alloys to regulate temperature and making solar cell panels as a semiconductor.  Finally polonium has been used in thermoelectric cells because it releases a large amount of energy.

So these elements in a stair-like formation next to the non-metals in the Periodic Table have made quite a splash in our lives!

Activities for Middle School Teachers:

The first computers were automatic arithmetic engines.(Ref.6)  Logic has something to do with it and George Boole started it all.(See Nuggets)  Students can create and study Truth Tables.  The True or False will correspond to 1 or 0 (zero),switch on or off.  This naturally leads students to review/study binary numbers and compare with the decimal system used in arithmetic.  Instructors could help in letting students see the direct connection between binary numbers and computer arithmetic.

Students can look at the history of the digital age from 1947 onwards.  How do the innovations of say, Apple, social media like Twitter,Facebook etc and on-line ordering services affect our daily lives?  How has it affected small stores using traditional/ old modes of business practices?  Let students compare the seismic shifts in our lives today versus the onset of the printing press or the invention of the telephone.

Nuggets of Information:

John Bardeen, Walter Brattain and William Shockley at Bell Labs developed the transistor on December 23, 1947.(Ref.3)

Transistors replaced vacuum tubes in computers in 1954.(Ref.3)

A diode is the simplest possible semi-conductor device, also called a one- way turnstile for electrons.  The transistor is caused by using three layers of N-P-N or P-N-P sandwich; the transistor could be a switch or an amplifier.  A silicon chip is a piece of silicon with thousands of transistors!(Ref.5)

Boolean logic was developed by George Boole in the mid-1800s.  It allows a few unexpected things to be mapped into bits and bytes ( little pathways of logical information).(Ref.7)

References:

1.http://www.chemicalelements.com/groups/metalloids.html

2.https://www.britannica.com/science/metalloid

3.http://www.computerhope.com/jargon/s/semicond.htm

4.schmoop.com/periodic-table/metals-metalloids.htm

5.electronics.howstuffworks.com.diode/.htm

6.i-programmer.info/babbages-bag/235-logic-ev

7.computerhowstuffworks.com/Boolean.htm

Science Makes Sense-Week41:Noble metals

July 11, 2016

In many Indian households, a family’s worth/status is measured by the amount of gold or silver jewelry the women wear.  For many years, actual gold coins were used as monetary currency till other metal coins were produced.  The U.S. Treasury printed the first paper money in 1861.  By the mid 1800’s most of the trading countries wanted to standardize transactions in the booming world market.   They adopted the gold standard.  This meant that governments could redeem paper money for its value in gold.(Ref.1)

Gold,Au, silver,Ag, platinum,Pt, along with other elements  like ruthenium, rhodium,palladium, osmium, iridium, are considered to be the noble metals since they do not oxidize or react easily under normal conditions like most other elements.   These eight elements form a rectangle block in the transition metals group.  The field of physics restricts the definition to include only three elements: gold, silver and copper,Cu, because these three elements have filled electronic ‘d’ bands.  However, in chemistry, copper is known to react quite well and form a series of well-known compounds, hence the former collection of noble metals makes more sense.(Ref.2)

These noble metals make excellent catalysts , especially platinum, since they are not easily oxidized or react with other chemicals that quickly.  Since Noble metals do not react so easily, they are used to clean car exhausts besides being perfect as catalytic  agents.  They are specifically used as catalysts in the manufacture of nitric acid from ammonia. (Ref.3)

Extraction of noble metals: Some of the Noble metals like platinum, iridium and rhodium are found in mines (Check Nuggets) located in some regions all over the world.  The sponge, which is what the raw material from the mines is called, is heated and turned into grains and then big bars or ingots.  After that it is heated again and hammered, it is turned into coils that are further heated to be drawn into very thin wires.  These thin wires are weaved or knitted into fine meshes.  These meshes are used as catalysts in reactions indicated above.(Ref.3)

Other uses of Noble Metals:

Ruthenium,Ru, is used to strengthen alloys with platinum,Pt and palladium, Pd, for electroplating electrical contact materials to be corrosion-resistant, on tips of fountain pen nibs, as a catalyst to split hydrogen sulfide, H2S, and in catalytic converters in automobiles. Rhodium,Rh, is used as a 3-way catlaytic converter in industry and in the production of acetic acid, CH3COOH, from methanol, CH3OH.  It is also used in the electroplating of platinum, Pt and white gold.  Palladium,Pd, is used mainly in jewelry, dentistry, watchmaking, spark plugs for aircraft, surgical instruments.  Iridium,Ir, is a very hard metal and has many applications in industry.  Because of its great resistance to corrosion and a high melting point, it is used in specialized spark plug manufacturing, pen nibs,  as a catalyst and for electrodes.  Machinery parts like spinnerets, balances and high temperature crucibles in the laboratory are also made with iridium, Ir.   The metals, platinum, Pt, gold, Au, and silver,Ag are used as bullion metals, i.e., in making coins as well as jewelry.  Ag is used as an anti- bacterial  medicine, and Pt is used extensively as a catalyst and for electrodes. Meanwhile Au has been used for years  and years to make coins and as a currency.(Ref.4)  Osmium,Os, is used as an alloy ( 90%Pt and 10%Os) for making surgical instruments and the manufacture of pacemakers.  Osmium tetroxide, an oxide of osmium, OsO4, is used in microscopy as a stain for fatty tissue and in fingerprint detection. (Ref.5)

The noble metals group play an important role in our lives, even though they are not as reactive as other metals in the Periodic Table.  Perhaps their low reactivity makes them unique in their applications.

Activities for Middle School Teachers:

What a wealth of fields one can study here: history, geography, economics, science and several cultures!  Let students look at a map and focus on the area once known as Lydia and find out how they fashioned gold.  Where was gold concentrated in the Americas? Study history and geography as the students look at the Aztecs, the Incas and the arrival of Columbus, the conquistadores and the fight for gold.   How did the English colonials in India plunder the gold and wealth there?   Study the wealth in Europe and the Americas especially in some of the old palaces, churches in France, Austria., Germany, Spain, Central America.  Look at the timeline of how gold has been considered such a valuable asset in so many ecomomies.  How do different cultures use gold, silver and the other noble metals today?  Students who come from India can talk about how people wear gold jewelry especially during weddings and special occassions.  Use pictures and take photographs of Indian weddings if possible.

Nuggets of Information:

Sometimes mercury and rhenium are included in the list of noble metals.(Ref.2)

By 560, the Lydians ,in the region between the Mediterranean, Aegean and Black Seas where modern Turkey is situated, succeeded in separating silver from gold and created the first gold coins.(Refs.2,6)

During the days of exploration, the wealthiest country had the most gold.  This explains the reasons why countries like Spain, Portugal and England vied with each other to send explorers like Columbus and others to places like the New World ( the Americas) and the east in search of gold.(Ref.2)

The gold rush of 1948-49 in California initiated the unification of the western part of the United States of America.(Ref.2)

Sometimes the people who work in the manufacture of noble metals from mines use special brushes to recover noble metals from their shoes.  This is called sponge.  One ounce of sponge is obtained from 10-40 tons of rock.(Ref.3)

Noble metals are found in mines that are in South Africa, Canada, Russia  and Zimbabwe. Processing of platinum takes 6 weeks while rhodium takes almost 6 months.(Ref.3)

Palladium is used for blood sugar testing strips and is one of the 4 bullions used by ISO (International Standards Organization) for currency codes.

Rhodium is used as a filter in mammography systems, neutron detectors in combustion systems. Ruthenium is used as a biological stain; staining pectin and nucleic acids.(Ref.4)  A biological stain is used to highlight biological tissue details. (Ref.7)  

When crude platinum was dissolved in aqua regia (a mixture of concentrated nitric and hydrochloric acid: HNO3+HCl) a black metallic powder was formed.  In 1803, the English chemist Tennant recovered  osmium and iridium from this mixture.   The name ‘osmium’ comes from the Greek word ‘osme’ which means unpleasant odor. Os and Ir are very dense; Os is the densest element known.   OsO4, osmium tetroxide is highly toxic and causes lung, skin and eye damage.(Ref.5)

References:

1.http://useconomy.about.com/od/monetarypolicy/p/gold_history.htm

2.http://chemistry.about.com/od/metalsalloys/a/Noble-Metals.htm

3.https://www.bing.com/videos/search?q=where+do+you+find+ruthenium%2c+rhodium%2c+osmium%3f&view=detail&mid=6B2D091A3581A6CE0D986B2D091A3581A6CE0D98&FORM=VIRE

4.http://www.ehow.com/list_6003330_uses-noble-metals.html

5.http://www.chemicool.com/elements/osmium.htm

6.http://www.kidspast.com/world-history/0045-lydians.php

7.http://www.organicdye.com/dyes/biological-stains/

 

 

 

Science Makes Sense-Chemistry and Social Justice-Week40: Fats, salt and sugar: are we eating too much?

June 28, 2016

Two famous Michaels, Michael Pollan and Michael Moss lament the fact that we are cooking less and relying on fast foods.  In their books, ” Omnivore’s Dilemma”,  “Cooked”( Michael Pollan) and “Salt, Sugar, Fat”( Michael Moss), they outline how food is delivered and how home cooking is being sidelined in many houses.(Refs.1,2,3)

I was fortunate to grow up in a home where my parents cooked most of the time.  Even when I started living away in my own home, I did cook almost every day and going out was relegated to once a month or every two months.  These days, I prefer a simple meal at home.  However, most working people eat at odd times and sometimes order in, since they come home tired to plan and prepare a meal.  This has led to more consumption of oily foods, laced with extra salt and desserts/breakfast foods loaded with fat and sugar.  It is also true that the availability of fresh fruits and vegetables at reasonable prices is not as easy in poorer neighborhoods where fast food restaurants are seen more often.  Today we shall look at the prevalence of fast and convenience foods, who tends to buy them and what measures are being taken in certain neighborhoods to encourage healthy eating. We shall look at the additives added in convenience and fast food as well and revisit the saturated, unsaturated as well as trans fats discussion.

First we will look at the term’processed food’.    Processed food is different from home-cooked food in the sense that additives are added to preserve shelf life.  The simplest processed food we see in the supermarket is canned soup.  What does it contain?   A lot of salt is added to preserve it and other additives are also added.  In the inner linings of food cans you find BPA, (Ref.4) which is chemically a bis phenol derivative where two phenol rings are connected via three carbon chains. (Ref.5)  BPA has been known to leach into the soup itself and cause obesity as well as breast and prostate cancers; it has even caused behavioral problems in young girls.  Salt as we know it is sodium chloride, NaCl, and high amounts of sodium ions is known to be responsible for heart attacks and  has lead to strokes (Ref.4)

Besides the additives indicated above let us look at food flavorings and colors, preservatives, chemicals added to change the texture of processed foods.  Among artificial flavoring, butyl alcohol,C4H9OH is one chemical that is added to mimic flavors of naturally occurring foods like butter, fruits.  There are serious health problems caused by too much consumption of this food flavoring.  Artificial sweeteners like aspartame, splenda are used by people with diabetes.  We know that regular sugar causes obesity and heart problems, but the artificial sweeteners consumed continuously causes headaches, seizures and even hallucinations. Benzoic acid(C6H5COOH)  is used  as a preservative in certain pickles, jams and fruit juices and this can cause asthma attacks, hyperactivity in children and neurological disorders.   Artificial colors like Blue 1,2 and some yellows and reds are known to cause certain kinds of cancers.  Vegetable oils that are brominated, ie contain Br, (bromine) a halogen,causes tremors and headaches.  (The Br is added as an emulsifier to prevent the oil from separating out). Carageenan, a  familiar thickener found in ice-creams, jellies has been found to form ulcers and cancers in animal studies.  High fructose corn syrup or HFCS  a fructose polysaccharide from corn, has been known to cause obesity and elevated cholesterol.  We already know the dangers of saturated fats ( less or no double bonds in the fatty acids that produce the oils/fats by esterification) but trans fats are even worse.  This is produced by forcing hydrogen gas over vegetable fats at high pressure and causing -COOH in trans positions hence the name’trans-fats‘.  Many fast food, especially fried foods contain trans-fats and the greater consumption has let to obesity among children and heart diseases.  Nitrates,nitrites of sodium(Na2NO3,Na2NO2) are used extensively in processed meat and is known to be a carcinogen.  And finally, sulfur dioxide, SO2, is added to dried fruits and is responsible for migraine headaches and asthma attacks.(Ref.6)

This list is not exhaustive, there are many more additives, fillers, flavors and colors used in processed foods that are not healthy at all.  But one would imagine that the above chemicals are enough for most of us to start cooking/ eating at home making simple, healthy meals while we know what is going inside our bodies.

But the switch is not easy and between the unhealthy but appetizing messages from the advertising industry, the convenience of ordering take-out and the higher prices of good healthy foods makes it very challenging for consumers to eat a balanced, nutritious meal everyday. (look at Activities and Nuggets)

Activities for Middle School Teachers:

Teachers can encourage students to map out their neighborhoods and actually find out what kind of food stores are available close by.  Then  each student can bring a can of food from home and find out what are the ingredients in them.    What chemicals are there in the additives? Why are they added to the food?  Is it made close by or comes from a far off place?  The teacher can then link geography with that particular can of food and ask students to see why that can of food  had to come from so far away.   The teacher can  introduce words like “locavore”  and”CAFO”and explain the meaning.  What alternatives would make sense? How did their grandparents obtain their daily food?  They could interview each other and find out how often they eat at fast food places, whether their family or friends have a vegetable garden in the summer and where they buy their groceries.  Does culture, where they come from influence what they eat?  Are students willing to try foods from different countries?  What limits them ?  Does having more money make people eat better food?   Does food advertising affect their daily food habits? Why or why not?

Students can also do research on where the food is grown, how it is grown and the difference between organic and regular food, GMO and non-GMO food, and humane or inhumane ways of raising chickens,animals for food consumption and who can afford which kind of food.

Nuggets of Information:

Most artificial flavorings have been banned in the European Union.(Ref.6)

“Food First ” is a book written by Fraces Moore Lappe where she encourages people to understand the politics of food and why growing your own food is the best way to control what one can eat.(Ref.7)  It is also necessary not to be a passive consumer but understand that supermarkets encourage us to consume high fat, high sugar products by simple things like arrangement of cereals / cans/ processed foods in an aisle.(Ref.8)

Morgan Spurlock in the movie”Supersize Me” makes us think twice about eating at fast food places too often.  He actually did an experiment on himself by eating fast food day and night for a month at McDonald’s and noticed how adversely it affected his own health!(Ref.9)

CAFO, or concentrated animal feeding operations or factory farms, keep animals in small confined spaces to feed and take care of them before butchering them for meat.  There have been enough studies done to show that the process is inhumane and unhealthy.(Ref.10)

References:

1. Pollan, Michael, Omnivore’s Dilemma (Penguin Press,2006)

2.Pollan, Michael, Cooked (Penguin Press,2013)

3.Moss, Michael, Salt, Sugar, Fat (Random House,2013)

4.http://www.rodalewellness.com/health/canned-soup

5.http://www.chemspider.com/Chemical-Structure.6371.html

6.http://peopleforethicalliving.com/health-and-fitness/food-choices-nutrition/dangerous-food-additives/

7.Lappe, Frances Moore,Food First (Souvenir Press Ltd.,1980)

8.http://www.regainedwellness.com/supermarket-psychology/

9. Supersize Me! the movie with Morgan Spurlock

10.Foer,Jonathan Safran ,Eating Animals (Little Brown and Co.,2009)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Science Makes Sense- Week 39:Organic Chemistry,Lipids, oils and fats

June 21, 2016

Almost every child in America gets its first taste of fast food with a packet of fries: Mmmm…so good! As children we grew up with occasional treats of fried potatoes that were irresistible. When I first landed in the U.S.,I always bought a bag of potato chips to remind me of fried food in India.
Oil has a unique way of adding flavor to any food. Today let us look at the chemistry of oils. Lipids are biological chemicals that do not dissolve in water.(Ref.1) These are a group of fat soluble compounds found in the tissues of plants and animals. Fats and oils are a sub-set or subgroup of lipids and are basically storehouses of energy. But lipids play an important role in the formation of cellular membranes,cellular signaling, nutrient functions with relationships to vitamins A,D,E,and K as well as being storehouses of energy. Furthermore, lipids are complex molecules with carbon, hydrogen and oxygen as well as nitrogen and sulfur and other small constituents.(Ref.2)
Fats and oils share a common molecular structure; fats are solids at room temperature, oils are liquids. What is the molecular structure?
They are esters of tri-alcohols, i.e., three -OH groups,also called glycerols,hence fats and oils are also commonly known as glycerides.  An ester has the H in the -OH group replaced by  a carbon chain and since there are 3 -OH groups there could be three different carbon chains called R1, R2 and R3 respectively.(Ref.1)  Remember that an ester in organic chemistry is like a salt in inorganic chemistry .  A salt is the neutralization reaction between a base/alkali and an inorganic acid, whereas an ester is a similar kind of neutralization reaction between an alcohol and an organic acid.   The more accurate name would be Triacylglycerols.   Hydrolysis (or reaction with water) of fats leads to glycerols and fatty acids.(Ref.1)

Triglyceride molecules contain carbon and hydrogen molecules and usually six oxygen atoms in every molecule.  This makes them highly reduced or unoxidized.  They resemble the hydrocarbons in petroleum and are good sources of fuel.  In fact the normal human body stores fats as fuel/ energy for several weeks’ survival.  Plants too do the same thing and this allows them to deal with unpredictable sources of food supply.(Ref.1)

A triglyceride is called a fat if it is a solid at 25°C, if it remains a liquid at this temperature, it is termed an oil.  The difference in melting point reflects the difference in the degree of unsaturation and number of carbon atoms in the original fatty acids that resulted in the triglyceride. (Ref.3)

Pure fats and oils are colorless,odorless and tasteless.  They are lighter than water, their densities are usually around 0.8gm/cc. They are poor conductors of heat and electricity and hence are excellent insulators for the body, slowing the loss of heat through the skin.(Ref.3)

The double bonds in fats and oils can undergo hydrogenation as well as oxidation.  The hydrogenation of oils is used commercially to produce margarine.  Most fats are obtained from animal sources whereas most plant sources produce oils.  Saturated fats/oils are derived from saturated fatty acids ( less or no double bonds) while unsaturated fats/oils are derived from unsaturated fatty acids ( more double bonds).  The high consumption of saturated fats, along with high cholesterol leads to increased risks of heart disease..(Ref.3)

The study of lipids, fats and oils indicates how necessary they are in the function and maintenance of our body’s functions.  However, too much of saturated fats and oils consumption today, especially because of the  fast food industry and in the changes in our lives has led to all kinds of medical problems.  We shall look closer at this topic next week.

Here is a small table to illustrate the predominance of saturated fatty acids in fats and more of the unsaturated fatty acids in oils:.(Ref.4)

Animal fats   Saturated acid(%)             Unsaturated Acids(%)

C10 &less     C12     C14     C16    C18        C18(a)C18(b) C18(c)

Butter     15         2          11        13        9            27      4         1

Lard             –        –             1         27     15          48    6          2

Plant oils               Saturated acid(%)           Unsaturated acids(%)

Coconut     –       50           18        8     2             6      1           –

Corn           –        –             1        10      3            50     34        –

Olive           –         –           –          7        2             85       5       –

Safflower   –         –            –         3        3             19     76       7

Activities for Middle School Teachers:

Let students make models of different fatty acids and triglycerides. Students need to research the reasons why unsaturated fats are not solids even though there are more double bonds here and the molecule ( fatty acid or corresponding triglyceride) may be dense and therefore could become a solid.  The Van der Waals weak intermolecular forces are stronger when you have long chain straight molecules; this happens with saturated fat molecules.  On the other hand, the presence of double bonds causes kinks in the structures making them non-planar.  Students will find a relationship between melting points and straight-chain versus non-planar structures. Students can plot a graph and present results.(Ref.5)

Nuggets of Information:

When all three hydroxyl groups (-OH) groups in the glycerol molecule are esterified with the same fatty acid, the resulting glyceride is called a simple glyceride.  In nature, you never see a simple glyceride, since the esterification in nature involves several different fatty acids.  That is because naturally occurring acids are a mixture of several fatty acids.(Ref.3)  No single formula can be written to represent naturally occurring fats and oils.  They may be derived from several different fatty acids.  Palmitic acid is the most abundant saturated fatty acid and oleic acid is the most abundant unsaturated fatty acid.(Ref.3)

Even though most fats are derived from animals, the exception is fish oil; triglycerides from fish are found as oils..(Ref.4)

Seeds contain a lot of oil/fats; the stored energy helps seedlings during germination.  later, they have solar energy available for photosynthesis.(Ref.3)

Hydrolysis of fats and oils in the presence of a base produces soap and the process is called saponification.(Ref.3)

Lipids can be  further classified as fats, oils, phospholipids, waxes, sterols .(Ref.4) Phospholipids  are a class of lipids similar to triglycerlides , where the fatty acid from which it is derived contains a phosphorus atom; they are present in cell membranes. Sterols are a class of lipids with structure similar to cholesterol.(Ref.6)  Cholesterol comes under the umbrella of steroids which have a carbon backbone with four fused ring-like strucures and a hydoxyl group (-OH).  Waxes are esters of a long-chain fatty alcohol and a fatty acid.  Many plants and fruits have a waxy coating to prevent water loss.(Ref.7)

Ear wax is composed of phospholipids and esters of cholesterol!(Ref.7)

References:

1.http://scifun.chem.wisc.edu/chemweek/pdf/Fats&Oils.pdf

2.http://www.differencebetween.info/difference-between-lipids-and-fats

3.http://chemwiki.ucdavis.edu/Textbook_Maps/General_Chemistry_Textbook_Maps/Map%3A_The_Basics_of_GOB_Chemistry_(Ball_et_al.)/17%3A_Lipids/17.2_Fats_and_Oils

4.http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/lipids.htm

5.http://chemistry.stackexchange.com/questions/4058/saturated-vs-unsaturated-fats-structure-in-relation-to-room-temperature-state

6.https://quizlet.com/94654736/chapter-5-lipids-fats-phospholipids-and-sterols-flash-cards/

7.http://biology.about.com/od/molecularbiology/ss/lipids.htm

 

 

 

 

 

  

Science Makes Sense Week 38:Noble gases

June 13, 2016

I remember when I was young, I liked stretching on a black sofa almost upside-down and reading a book. My mother would come and implore me to go out and I would be oblivious to her presence. “Why aren’t you reacting? It is as if you are in another world!”, she would remark in dismay.
Sometimes, when I look at the last group in the Periodic Table, the Noble Gases, I wonder if they too belong in another world. Helium,He, neon, Ne, argon, Ar, krypton,Kr, xenon, Xe and radon, Rn are the six common noble gases. All these are obviously gases and the outer electronic structure is a stable octet, which is really a ns2 np6 configuration, where n=2 through 6. The exception is helium, which has a stable duplet or 1s2 structure.
One has already seen that the alkali and alkaline- earth elements try to lose one or two electrons to achieve the stable noble gas structure. In addition we have seen that the halogens gain an electron to have the outer stable electronic structure of noble gases. In fact, almost all elements in the periodic table gain or lose electrons during a chemical reaction to get to the stable electronic structure of these noble or inert gases. This also implies that the last group elements are not reactive. Now is that really a fact?
Till the early 60’s, scientists were talking about the stable octet/duplet rule to justify the non-reactive nature of these gases. Initially it was called Group 0 for this reason. In 1962 and 1963,scientists observed that some of the noble gases,like radon, krypton and xenon form different flourides. In addition, in 2006, scientists in Dubna, Russia, announced that the element 118, the next noble gas, was synthesized in 2002 and 2005 in a cyclotron.(Ref.1) A cyclotron is a high particle accelerator where subatomic particles like protons and electrons are in a magnetic and electrical field and can collide at high speeds with each other.(Ref.2)
Hence there are really 7 noble gases present and since some of them are not completely non-reactive, the noble gases group is now called Group 18 and not Group 0.(Ref.1)
The noble gases are all colorless, odorless, tasteless, non-flammable gases. They also happen to be mono-atomic gases, ie, they exist as individual atoms rather than di- or poly- atomic molecules.(Ref.3) They were originally called inert or rare gases. They are neither inert(since we know some of them react with flourine to form compounds) nor rare, because several of them are found in abundance on earth.(Ref.1) Yet the word’noble’ is appropriate, since certain elements like gold or platinum are also considered ‘noble metals’ because of their reluctance to undergo chemical reactions easily.(Ref.1)
How abundant are these noble gases? It is noted that their abundance decreases with increase in atomic weight, with He being the most abundant while there are only three molecules of element 118! Most of the noble gases are present in the earth’s atmosphere, except for helium, radon and are recovered from the air by obtaining them as liquids and conducting fractional distillation to separate them.(Ref.1) (Fractional distillation is a technique whereby different liquids can be distilled/condensed using differences in their boiling points, to collect each substance separately.)
Actually both radon and even helium are by-products of radioactive decay. After the discovery of radium by the Curies, German physicist became fascinated with radium and discovered a gas that it emitted and he called it ‘radium emitting; he discovered the new element, radon. The breakdown of radium as well as uranium can lead to the production of helium ions as well.(Ref.3)
The noble gases are used in many daily and specialized applications. Helium as we already know has been used in the filling of balloons, for large airships and for children. Helium is also used by divers not for buoyancy but to prevent “the bends” a condition when nitrogen bubbles in the blood as a diver comes up to the surface. Helium is extensively used in the field of cryogenics which is low-temperature science. Neon is best known for its use in neon signs, neon glow lamps are used to indicate on/off signs in electronic instrument panels and in early televisions. Even though radon is considered a hazard it has its uses in earthquake detection, leaks, measuring flow rates. Paleontologists, who study the distant past as well as geologists use argon dating to study volcanic layers, fossils etc. Krypton is mixed with argon in the manufacture of windows with high thermal efficiency, used in lasers as well as halogen headlights. Along with xenon, especially because of its lower cost, krypton has been used as a fuel in space.
(Ref.3)

As one can see, these noble gases are not so quiet and inert as they seem.
Activities for Middle School Teachers:
Have a discussion with students about how certain words like ‘inert’, ‘rare’ to describe the Group 18 gases is really not accurate. Look at the history of the ‘phlogiston’ theory and how the burning/oxidation theory was modified with further experiments in science. Look at the history of the atomic models and see how those models evolved with time and more knowledge. How did the invention of new instruments in the laboratory aid these developments? Compare the evolution of ideas in chemistry, physics with say, social sciences and psychology.
Nuggets of Information:
In 1868, a French astronomer named Pierre Janssen (1824-1907)came to India to observe a total solar eclipse. Using a spectroscope, an instrument for analyzing the spectrum of light emitted by an object, Janssen was able to show a yellow line in the spectrum, never seen before, which seemed to indicate the presence of a previously undiscovered element. He called it “helium” after the Greek god Helios, or Apollo, whom the ancients associated with the Sun.(Ref.3)
Helium is remarkable since it only liquefies close to absolute zero(-272 degrees celcius); that makes it very difficult to liquefy from air.(Ref.3)
Almost all the noble gases have derived their names from the Greek language. Neon comes from the word ‘neos’ which means new,argon from ‘argos'(inactive), krypton from kryptos,(hidden) and xenon from the word ‘stranger’.(Ref.3)
Superman’s kryptonite is an imaginary substance and has no relationship with the noble gas krypton.(Ref.3)
The discovery of radon starting with the element radium was the first clear proof of one element being transformed to another element through radioactive decay. (Ref.3)
Within the atmosphere,, argon is considered the most ‘abundant’ of these gases, about 0.93%.(Ref.3)
Until 1988, most Americans had no knowledge of the existence of radon, when the EPA(Environmental Protection Agency) released a report indicating the harmful effects of radon in homes. From the 80s through the 90s radon detector sales boomed; even today when a house is sold, radon levels need to be checked. This is especially needed if a house has been weather-sealed to improve heating and cooling.(Ref.3)
Chinese scientists made an interesting discovery in the 1960s. Radon levels in groundwater increased significantly before an earthquake. These scientists monitor radon levels to predict earthquakes.(Ref.3)
References:
1.http://www.britannica.com
2.http://www.thefreedictionary.com/cyclotron
3.encyclopedia.com/topic/Noble_gases.aspx

Science Makes Sense-Week 37: The alkaline earth metals

May 17, 2016

My grandmother was very particular that all the grandchildren who came to visit her had milk at night. She would stand with a big warm container of milk and insist that we all had a small glass before we went to bed. My younger sister hated this white liquid and would swallow it with great difficulty. Even now she dislikes the taste of milk but gets her calcium from plenty of yogurt and dietary supplements.
Calcium,Ca, is one of the alkaline-earth metals along with Beryllium,Be, Magnesium,Mg,Strontium,Sr, Barium,Ba and Radium, Ra. (Radium was covered last week) All are metals and form Group 2, next to the Group 1 alkali-metals in the Periodic Table. Like the alkali-metals, they are soft, silvery-white metals, reactive (but not as reactive as the alkali-metals) and never found as an element in the natural state. And again, like them, they glow with characteristic colors and are distinguished by the flame test. Unlike the alkali-metals which have 1 electron in the ‘s’ shell, they have two electrons in the ‘s’ shell.(Ref.1)
Some of the alkaline-earth metals except radium and beryllium were discovered by the English Chemist, Sir Humphrey Davy in the early part of the 19th century. Around this period, Sir Davy also discovered two of the alkali-earth metals, potassium and sodium.(Ref.1)
The alkaline-earth metals react easily with water to release hydrogen gas and form the metal hydroxide. Many of them react with oxygen to form oxides. In nature they are usually found as sulfates and carbonates.(Ref.1)
The most abundant of these metals is calcium, Ca. It is the fifth most abundant element in the earth’s crust as well as in the human body. Magnesium, Mg is the seventh most abundant element in the human body, whereas Ba, Be nor Ra, St are found in the body, since the first two are poisonous while radium is radioactive; meanwhile strontium is only present as 360 ppm on the earth’s crust.(Ref.1)
Beryllium is used in the health-care industry, (besides being found in precious stones)in X-ray tubes as well as in alloys for specialized electrical connections and for high-temperature uses.
Besides magnesium being important as a digestive aid and formerly used for asbestos, today it is used in the manufacture of fertilizers. Because of its property to burn in oxygen with a brilliant flame,in World War 1, magnesium was used as flares, tracer bullets and incendiary bombs. Later in World War 2, it was used to build aircraft and military equipment. Today it is used with other metals to manufacture catcher’s masks, skis, race cars and even horseshoes.(Ref.1)
Calcium has been used in buildings from ancient times. Steel, glass, paper and metallurgical industries use slaked lime(calcium hydroxide, Ca(OH)2). Acetylene used for welding is made by reacting calcium carbide(CaC2) with water. Calcium compounds are also used as a bleach, fertilizer and sometimes to melt ice on roads.
Even though strontium is not as abundantly available it still has several uses. Like magnesium, it is used for flares, tracer bullets and also for fireworks- having a brilliant crimson color. It is also used in color television picture tubes, to refine zinc and combined with iron, strontium is used to make magnets.(Ref.1)
Barium compounds are used extensively in health care applications: in enemas and also to coat inner linings of intestines so doctors can examine the patients’ digestive system.(Ref.1)
The alkaline-earth elements are used in a wide variety of ways; they are not just known for calcium and strong bones.
Activities for Middle School Teachers:
Study the boiling and melting points of the alkaline- earth elements. Is there a correlation between them and their atomic numbers as in the case of alkali-metals?
Helium,, He, has two electrons in its outermost ‘s’ shell, why then does it not behave like an alkaline-earth metal? Let the students discuss this with the teacher.
Nuggets of Information:
Beryllium is found in emeralds and aquamarines as a compound of beryllium and alumino-silicate and is called beryl.(Ref.1)
Magnesium is found as dolomite or magnesite which are carbonates of magnesium, MgCO3. (Ref.1)
Calcium is found mostly as limestone and as dolomite (calcium carbonate, CaCO3) and also as gypsum(calcium sulfate, CaSO4)
Strontium was initially discovered by Adair Crawford, an Irish Chemist in the late 18th century in witherite; it is also found in strontianite(strontium carbonate, SrCO3) and in celestite( strontium sulfate,SrSO4)(Ref.2)
Barium is found as barite(BaSO4,barium sulfate) or witherite(BaCO3,barium carbonate)(Ref.3)
Magnesium sulfate, also known as Epsom salts has been long known for their medicinal value,mainly in Epsom salts springs. It has also been used for the treatment of eclampsia, a condition that causes seizures in pregnant women.(Ref.1)
Salts of magnesium are used as a powerful laxative(Ref.1) but magnesium hydroxide,Mg(OH)2 also known an milk of magnesia is the preferred laxative.(Ref.4)
One of the most controversial uses of magnesium has been in asbestos, as a fire retardant. It is a silicate of magnesium with the formula Mg3Si2O5(OH)4. This had been used for commercial purposes 95% of the time.(Ref.5) For years it was used as a flame-retardant till it was found to be cancer-causing and had to be removed from many buildings. In spite of this, magnesium as an element is important in the health of living organisms.(Ref.1)
Magnesium plays a critical role in chlorophyll, the green pigment in plants that gets its energy from sunlight.(Ref.1)
More than magnesium, calcium is vital for living beings and is present in leaves, teeth, bones, shells and coral.(Ref.1)
We all know that calcium is essential for bone-building but it also plays an integral part in almost every cell in the body especially in the growth of muscles, the nervous system as well as the heart.(Ref.6)
Osteoporosis is caused by a loss in bone density and can be prevented by eating foods high in calcium like green vegetables and dairy products.(Ref.1)
An isotope of strontium, Sr 90, is radioactive and is a by-product of nuclear testing from the ’40’s. Once, during testing, this isotope fell to earth, coated grass and was ingested by cows. The milk from these cows was drunk by many children when the Sr 90 got into their teeth and gums causing many health problems. In the 60’s atmospheric nuclear testing was stopped. Strontium 90 affects production of red blood cells and could lead to death.(Ref.1)
Prior to receiving X-rays, patients drink a chalky barium sulfate,BaSO4 solution which absorbs radiation and adds contrast to the image.(Ref.1)
References:
1.http://www.encyclopedia.com/topic/alkaline-earth_metals.aspx
2.http://education.jlab.org/itselemental/ele038.html
3.http://education.jlab.org/itselemental/ele056.html
4.https://www.medicines.org.uk/emc/medicine/17293
5.http://www.britannica.com/science/asbestos-mineral
6..http://www.helpguide.org/articles/healthy-eating/calcium-and-your-bones.htm

Science Makes Sense-Week 36: Chemistry and Social Justice-radiation, radium girls.

May 9, 2016

I remember when I was six or seven, my uncle came to visit us in the evening when we had a power cut in India and had no electricity. Everything turned pitch dark but I could see my uncle’s watch gleaming green in the dark! “Why is that happening? Do you have a magic watch?” I exclaimed. ” No magic, it is a glow-in-the-dark watch,” he responded. I was fascinated and learned years later that it was a radium watch. The dials had been painted with a salt containing radium.
Today we shall look closely at the discovery and use of one of the radioactive elements, radium (mention others in nuggets) and the terrible results of exposure due to ignorance and careless/negligent planning.
Radium was discovered by Pierre and Marie Curie in 1897 along with Polonium.(Ref.1) Pierre and Marie Curie were unaware of the dangers in the late 19th century/ early 20th century about nuclear reactions.
Most chemical reactions occur through transference/sharing of electrons, those very tiny particles that circle far away from the nucleus of an atom of any element. The nucleus is not touched in such reactions; however by the end of the 19th century, scientists were entering the realm of nuclear reactions. The nucleus is where the protons and neutrons are situated. The energy released when the nucleus is attacked, is several times that of a chemical reaction. Such attacks can be man-made as in nuclear reactors, and the explosion of atomic bombs, but radioactive elements that naturally decay can also cause nuclear reactions.
In fact Henri Becquerel was the first to observe mysterious radiation in uranium compounds and Maria and Pierre Curie did measurements on the amount of radiation emitted.(Ref.1) It is important to note that elements like technitium,Tc, prometheium, Pm as well as elements starting with polonium Po, all the way to the end of the Periodic Table exhibit radioactivity. In other words all the elements from atomic number 84 to atomic number 105 are radioactive, besides technitium and prometheium. Some of these elements are not too stable having very short half-lives.(Ref.2,3) Half life for an element is the time needed for half the mass of the element to decay.
The radioactive decay of elements leads to three kinds of ionizing radiation: alpha and beta particles as well as gamma radiation. Alpha particles consist of a pair of protons and neutrons, viz., it is a Helium ion. This is the least dangerous as far as radiation effects go, since they do not penetrate very deeply into clothing or skin. However, once ingested or inhaled through water or food sources, they could become carcinogenic and ultimately lead to lung cancer and other cancers. Beta particles are electrons that move very quickly; being 8000 times smaller than an alpha particle, this allows them to penetrate clothing and skin very easily. External exposure leads to burns and tissue damage and ingested/inhaled through water/food contamination could lead to serious health problems. Gamma rays are the most dangerous, these are fast-moving photons with no mass , passing easily through all body tissues and bone marrow causing extensive damage to the body and death based on amount/duration of exposure.(Ref.4)
While Marie and Pierre Curie may have been ignorant of the dangers of radium’s radioactivity, years later, many women were dangerously exposed to radium in U.S.factories where they were making radium watches and clocks. Referred to as the “radium girls” in Waterbury,Connecticut, Orange,New Jersey and in Ottawa, Illinois, young girls worked in factories and painted radium mixed as a paint with zinc sulfide, on dials of watches and clocks.(Ref.5) The managers, wanted them to lick the brushes so they were pointed to do the fine painting on the dials. Some of these girls even painted their buttons and finger nails to glow in the dark unaware of the terrible consequences. Initially because of ingesting alpha particles from the radioactive radium, they had terrible pains near the teeth and jaw, but eventually developed swelling and total destruction of the jaw and finally death in some cases. In Orange, new Jersey, 4 dial painters died and 8 were very ill. Dial painters there filed a suit in March of 1925 and following that workers no longer used their mouths to lick and point the brushes, they started wearing rubber gloves and use fume hoods after 1927. No more cases of cancers in dial painters were officially blamed on radiation. But the damage had been done.(Ref.5,6,7)
Years later, the suffering of the Radium girls led to safety measures for World War II atomic bomb workers.(Ref.5) Aah! But at what cost??
Activities for Middle School Teachers:
Teachers need to discuss how loosely and incorrectly certain words are used in daily life. The most common errors are made when the word ‘chemical’or ‘radiation’ is used, for example. All chemicals, radiation are considered harmful whereas water is also a chemical and electromagnetic radiation encompasses visible light. Let students research these words in science and understand the variation in meaning depending on context. Also, let students find other words in science that are mis-understood or partially explained by the non-scientific community.
Teachers should collaborate with Language Arts teachers and see if the word ‘synecdoche’ could be used to describe the incorrect usage of certain scientific words. (This word is a part of speech akin to a metaphor or simile; it means when a word is used to describe part of what it actually means)
Nuggets of Information:
Marie Curie’s notebooks and even her cookbook are so radioactively charged that they can only be viewed through lead screens today.(Ref.8)
Henri Becquerel received a burn carrying radium-rich barium chloride in his waist-pocket. Pierre Curie suggested that radium could be used for cancer therapy and in the 20’s it was used to treat some forms of skin cancer. In fact radium was touted as a cure for hypertension, diabetic pain, arthritis, gout and even for tuberculosis of the lung. Today, however radium is not used for any of this, but some research is underway to study its use to relieve intractable pain.(Ref.9)
Because of prolonged exposure to uranium, polonium and especially radium, Marie Curie succumbed to anemia related to radiation in bone marrow.(Ref.4)
The Geiger Counter was invented in 1928 and is used to measure radioactivity levels in many elements.(Ref.9)
It is important to note that all forms of radiation are not harmful to humans; e.g., electromagnetic radiation includes visible light. Also many man-made products like televisions,smart phones, microwave ovens emit radiation that are not dangerous and the danger varies with strength and length of exposure.(Ref.4)
There were 30 women in Connecticut, 35 women in Illinois and 41 women in New Jersey who died because of being dial painters (Radium Girls) in the 1920’s.(Ref.5)
Alexander Litvinenko, a former KGB officer died 3 weeks after ingesting a cup of tea containing Polonium 210.(Ref.8)
References:
1.http://chemistry.mtu.edu/~pcharles/SCIHISTORY/Marie_Curie.html
2.http://periodictable.com/Elements/Radioactive/
3.http://chemistry.about.com/od/nuclearchemistry/a/List-Of-Radioactive-Elements.htm
4.http://science.howstuffworks.com/radiation-sickness1.htm
5.http://www.waterburyobserver.org/node/586
6.Clark, Claudia, Radium Girls,(University of North Carolina Press, 1997)
7.Mullner, Ross, Deadly Glow,( American Public Health Association, 1999)
8.http://listverse.com/2010/03/25/10-famous-incidences-of-death-by-radiation/
9.http://www.rsc.org/images/Dronsfield_tcm18-200827.pdf

Science Makes Sense-Week35:Organic Chemistry,Benzenoid aromatic compounds

May 2, 2016

Every year my mother would clean her silk saris by washing them in mild soap, getting them ironed and stack them in the cupboard with a few moth balls. So every time I would open the cupboard to wear her saris I would smell the odor of moth balls and hope it did not cling to me! Moth balls originally contained naphthalene which is a benzenoid compound and we shall look at a few of these today.
Benzenoid compounds contain the benzene ring and last time we had a chance to look at the simplest of these, benzene. The structure of benzene was discovered almost simultaneously by Loschmidt and Kekule around the mid-19th century,(both German scientists) as a six-membered cyclic hydrocarbon containing 6 carbon and 6 hydrogen atoms with alternating double bonds. But it was Kekule who modified the structure to one where the oscillation of the double bonds gave two equivalent structures in rapid equilibrium. Then in 1931, Linus Pauling suggested that benzene had a single structure that was a resonance hybrid of the two Kekule structures.(Ref.1)
Benzene is a colorless volatile liquid with a characteristic strong odor and is the starting point for the manufacture of many aromatic compounds including aniline, phenols.(Ref.1)
Modern bonding models (valence bonding and molecular orbital theory) explain the stability of the benzene due to the delocalization of the six electrons. This delocalization refers to the attraction of an electron by all six carbon atoms instead of one or two, making benzene very stable. Unlike other unsaturated hydrocarbons, the hydrogenation and oxidation of benzene is a slow process. Most reactions of benzene are electrophilic aromatic substitution where the ring is intact and replacement of hydrogen occurs. Such reactions are important in forming derivatives of benzene.(Ref.1)
Benzene is present/manufactured in oil refineries, rubber and shoe manufacturing as well as in gas stations and firefighting.(Ref.2). Benzene has been documented as a cancer-causing agent and the results of exposure are mentioned in Nuggets.
The next aromatic compound we will study is toluene, also known as methyl benzene where one of the hydrogen atoms is replaced by a methyl(CH3)group. The odor is similar to benzene and it is usually a stable compound unless subjected to high temperatures. It is one of the by-products of gasoline production, but most of the benzene is manufactured starting with toluene. Toluene is used in the manufacture of adhesives, rubber, laboratory paints, pesticides and pharmaceuticals.(Ref.3)
The third set of aromatic compounds are called phenols. When a hydroxyl group, -OH group is attached to a carbon atom of a benzenoid ring, the compound is called a phenol. Phenols are similar to alcohols; however the hydrogen bond is stronger so they are more soluble in water than alcohols and have a higher boiling point. They are usually colorless liquids or white solids and are toxic and caustic. Household products that contain phenols include disinfectants and mouthwash. In industry, phenol is the starting point for plastics, explosives,photography, dyes and aspirin.(Ref.4)
Finally we will look at the chemical composition of moth balls, another benzenoid compound. Today we use dichloro-benzene , but years ago naphthalene was used in the manufacture of moth balls. 2 fused rings of benzene comprise naphthalene with the formula C10H8. Naphthalene is a white, solid crystal and has a strong odor of coal tar. It can undergo electrophilic aromatic substitution. It can be hydrogenated partially to form 1,2,3,4 tetra hydro-naphthalene or completely to form decalin, C10H18. Both are used as low volatile solvents. Naphthalene is used as a fumigant/ pesticide mainly as well as in the production of dyes.(Ref.5)
We have looked at some of the benzenoid compounds; we use them in our everyday lives. Look at Nuggets to realize that some of these compounds are carcinogenic, some are explosives and some are also medicines. However, all are essential in our lives today.
Activities for Middle School Teachers:
Benzene has 3 different positions on the 6 carbon atoms: Immediately adjacent to the first carbon atom is called the ortho position, next to it is the meta position and directly opposite to it is the para position. Create the basic structure of benzene using kits available and then substitute different methyl groups in the different positions. Name them. Then change the hydrogen atom in the first position and insert an amine or hydroxyl group and repeat the process. Find out if such benzenoid compounds exist and what their names and uses are.
Also create structure of aspirin and salicylic acid. What is the latter used for?
Build structures for other pain relievers like ibuprofin and tylenol; find out their chemical/generic names as well.
Nuggets of Information:
Most of the benzene was originally obtained from coal tar, but from 1950, it has been derived from petroleum-based processes. More than half the benzene is converted to polystyrene, a common plastic. The steps to the conversion as as follows: benzene to ethyl benzene to styrene and then the polymer polystyrene.(Ref.1)
Benzene is one of the twenty most widely used chemicals in the United States. It is used mainly to manufacture plastics, lubricants, rubbers, dyes, detergents, drugs, and pesticides. You could breathe or ingest this aromatic compound easily in such environments.(Ref.2)
Benzene is present in cigarette smoke; in the presence of smokers we inhale benzene vapor. In fact, cigarette smoking causes half the exposure to benzene in the U.S.(Ref.2)
Benzene is a known carcinogen and workers who are constantly exposed to it are at a higher risk in developing leukemia and related cancers.(Ref.2)
Toluene derived its name from a tree in Colombia which has an aromatic extract called tolu balsam.(Ref.3)
TNT or tri-nitro-toluene is a known explosive and is made from nitric acid and toluene.(Ref.3)
Toluene is also used as an octane booster in gasoline. In biochemistry experiments toluene is used to rupture red blood cells for hemoglobin extraction.(Ref.3)
Phenols were the first surgical antiseptic used in 1865. Surgical amputations fell from 45% to 15% after using phenols. However, they were toxic as well.
A less toxic phenol like resorcinol, that contains two hydroxyl groups is often found in cough drops.(Ref.4)
Picric acid, which is trinitro phenol is used as a yellow dye as well as an explosive like TNT.(Ref.6)
Trace amounts of naphthalene are found in magnolias and certain kinds of deer.(Ref.5)
Naphthalene is considered to be a carcinogen; excessive inhalation or ingestion could cause hemolytic anemia.(Ref.7) Hemolytic anemia is caused by the destruction of red blood cells in the body.(Ref.8)
Aspirin, which is also known as methyl salicylate or 2 acetoxy-benzoic acid is an analgesic and is a non-steroidal anti-inflammatory agent. It is used usually for minor headaches and pains. Aspirin exhibits anti-coagulant properties(Ref.9) and therefore small doses are recommended every day to prevent heart attacks for some patients. It is an aromatic benzenoid compound.
Aniline, which is benzene with a hydrogen atom replaced by an amine _NH2 group is essential in the manufacture of dyes. It is responsible for the indigo color in blue jeans. Aniline is also used to make polymers like polyurethane, fungicides and herbicides. It is also used to make additives in rubber.(Ref.10)
References:
1.http://www.britannica.com/science/benzene
2.http://www.cancer.org/cancer/cancercauses/othercarcinogens/intheworkplace/benzene
3.http://ezinearticles.com/?Toluene—Knowing-Its-Chemical-Properties,-Applications-and-Risks&id=2214472
4.http://www.britannica.com/science/phenol
5.http://www.newworldencyclopedia.org/entry/Naphthalene
6.http://www.britannica.com/science/picric-acid
7.http://npic.orst.edu/ingred/naphth.html
8.http://www.nhlbi.nih.gov/health/health-topics/topics/ha/
9.https://pubchem.ncbi.nlm.nih.gov/compound/aspirin
10.http://study.com/academy/lesson/aniline-structure-formula-uses.html