Archive for the ‘geography’ Category

Science Makes Senses Week 6: Sulfur, brimstone, rubber,sulfa drugs and alliums

September 27, 2015

Pope Francis is visiting the United States, and I could not help but think of the Catholic nuns in school who would scare us with words like ‘fire’ and ‘brimstone’.They would warn us about sinning and hell. ‘Brimstone’ was just another word for sulfur which is supposed to be burning forever in that nether place.

The word ‘sufra’ in Arabic means yellow and sulfur’s name could have been derived from it. Also in Sanskrit, sulfur was called ‘Shulbari’ which means ‘enemy of copper’ From ancient times it was known that metals like copper reacted with sulfur.

For years, people have believed that sulfur springs were good for their health and took daily dips in them. In fact, there are places in Texas and Florida named Sulphur Springs! Sulfur was also used as a fumigant (to control pests) thousands of years ago.Today I will talk about this useful element that we have known for so long and hope to separate myth from reality.

The chemical symbol is S. When sulfur burns in the presence of oxygen, it burns with a blue flame. and has a distinctive odor:

S +O2    →   SO2

                          ( Sulfur plus oxygen gives sulfur dioxide)

Match heads made of sulfur when burnt would lead to the same odor: same oxidation reaction, leading to sulfur dioxide.

Sulfur is lemon-yellow in color and is a non-metal. In the Periodic Table it is just under Oxygen, or in the same Group as Oxygen. (The rows in a Periodic Table are called the ‘periods’ and the columns are called ‘groups’.)

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Many vegetables we cook with have sulfur compounds in them including onions, garlic, cabbage. Eggs contain sulfur and rotten eggs have a distinctive smell because of hydrogen sulfide  H2S (a compound of 2 atoms of hydrogen and one atom of sulfur). Sulfur is found offshore in Texas and Louisiana and is not usually mined directly, since hydrogen sulfide, a toxic gas, is often present, along with sulfuric acid fumes. The sulfur is mined by the Frasch process, where hot water is pumped to the levels where sulfur is deposited and fairly pure sulfur is obtained. Actually, more and more extraction of sulfur takes place during petroleum production. However, in countries like Indonesia and parts of South America, even to this day sulfur is mined directly from volcano craters,  a job filled with hazards for the miners.

Sulfur is used in the vulcanization of rubber. Natural rubber tends to stretch or get hardened easily.Vulcanization is the addition of sulfur to natural rubber which then increases its tensile strength; an important property in the manufacture of tires. Today tires in the United States are mostly made using synthetic rubber versus rubber from a tree(natural rubber).

Most of the sulfur that is extracted is used in the manufacture of sulfuric acid and most of the sulfuric acid is used to make fertilizers and batteries. Sulfur is also used as a fungicide.

Before the manufacture of antibiotics we had sulfa drugs, chemically synthesized organo-sulfur compounds used to treat bacterial infections. (An organo-sulfur compound is a multi carbon,multi hydrogen and sulfur containing compound  with covalent bonding) (I will talk soon in my blogs about covalent bonding) In 1930, the first case is recorded where a sulfa- drug, a sulfanilamide molecule, cured bacterial infection successfully. Chemists were eager to synthesize more sulfa drugs and between 1935-46, over five thousand different variations of the sulfanilamide molecule was made.(Don’t be scared by the big name, this is an organic compound containing sulfur-‘sulfa’; the nitrogen with hydrogen indicates the ‘ amide’. As we continue to study Organic Chemistry, all these so-called complicated names will make sense.) Out of all the molecules synthesized, three more stand out: Sulfapyridine, used for the treatment of pneumonia, Sulfathiazole for the treatment of gastro-intestinal infections and Sulfacetamide for the treatment of urinary tract infections.

In fact, during World War I, (1914-18) there was no effective treatment available for bacterial infections. Because of infections like gangrene many soldiers had to have their limbs amputated or unfortunately, sometimes they died. During World War II, (1939-45) with the discovery of sulfa drugs Sulfapyridine and Sulfathiasole, veterans’ limbs and lives were saved. Sulfa drugs cured thousands of lives at home suffering from pneumonia and in the battlefield and were considered ‘wonder drugs’.Some of us born in the ’50s and ’60s are well aware of using these sulfa drugs.

The intriguing  fact is that these sulfa drugs do not kill the bacteria, which is what an anti-bacterial agent is supposed to do. Bacteria need folic acid to thrive and multiply inside our bodies. (Most of our folic acid comes from leafy vegetables that we eat.) The remarkable fact is that the middle portion of the folic acid  structure looks a lot like the structure of the sulfa drug. So the bacteria takes in the sulfa drug, thinking it is folic acid and dies.

Without sulfur chemists could not have synthesized these wonder drugs. Of course, today we have penicillin (naturally occurring substance that contains sulfur) and other antibiotics that are more effective , but we still use a few sulfa drugs for certain kinds of infections. This lemon-colored solid called sulfur plays a significant role in our lives. It is the 17th most abundant element on earth and the 10th most abundant element in the universe.

Activities for Middle School Teachers: If you have access to a laboratory, create some of the allotropes of sulfur, so students can observe the various crystalline shapes.

Collaborate with the geography/social studies instructor to find where sulfur is mined from volcanoes, where sulfur is extracted using the Frasch process and where sulfur is obtained during petroleum production.

Connect with history to look at young adult fiction based on World War I and II.Read books where veterans returned from World War I with limbs amputated.*

Let students interview family members (great uncles, great grandparents, great aunts etc) and learn about the use of sulfa drugs in their younger days during bacterial infections.

Nuggets of information: Sulfur dioxide was used as a refrigerant to create the first artificial ice-skating rink.

Elemental sulfur has several allotropes. When an element has one or more allotropes of itself it means it can be found having different structures. Sulfur exists as monoclinic, rhombic and plastic sulfur.

Hair,skin and  feathers contain a lot of sulfur,

Why do we cry when we cut onions? The cells of the onions release a sulfur containing compound that breaks down basically into sulfuric acid and other sulfur compounds, enters our eyes and reacts with the water there to sting our eyes and makes it water to flush the acid out.

Onions, leeks, chives, garlic all belong to the Allium family and they are all monocotyledons not dicotyledons. (i.e., when they sprout they have single leaves instead of two leaves.) Alliums absorb sulfur from the soil.


Le Couteur, Penny and Burreson,Jay,   Napolean’s Buttons: How 17 molecules changed History,(Jeremy P. Tarcher Putnam,2003)