Question

I'm helping my son make a two-page essay (I'm not here to talk about the essay), and the topic is about a consumer product and the chemistry behind it. The example his teacher gave is, "Take aspirin as the topic, and describe its therapeutic effects."

I am more than capable of helping him constructing the essay, but alas, I am no more skilled in chemistry than Dr. Frankenstein.

Answer 1

what's that?

Answer 2

im not asking about the therapeutic effects of aspirin. Im asking for a topic for the essay

Answer 3

Goodness, the possibilities are endless. Nearly every consumer product has some interesting chemistry behind it. Off the top of my head...

(1) Soap, of course. A very long and interesting history of how it was made, in the old days (and still by artisan soapmakers) from animal fat and the liquid leached from the burnt ashes of plants. The chemical reaction of a fat with an alkali is still called the saponification (= "soap making") reaction.

(2) Certain preservatives, like BHT, which reacts with peroxides to prevent their oxidation of (and therefore discoloration of) food, and EDTA, which is shaped like a claw and "chelates" (grabs hold of and sequesters) metal ions so that they do not catalyze reactions that might also cause food to decay.

(3) Water softening, which relies on exchanging Na+ ions for Ca+2 and Mg+2 ions in "hard" water, because the doubly-charged cations form insoluble "soap scum" precipitates with the anionic molecules in soap. Why Ca+2 and Mg+2 salts are less soluble than Na+ salts is something within the understanding of typical high school chemistry.

(4) Fluoride additives in drinking water and toothpaste, which act to harden tooth enamel by replacing the (OH)- group in the mineral making up tooth enamel with the F- ion. The resulting mineral is much more resistant to attack from acids from bacteria.

(5) Which brings up antacids, such as sodium bicarbonate and calcium carbonate, which chemically react with acids in the stomach to reduce stomach acidity. Sodium bicarb is often favored for its easy solubility -- you can make a nice solution to drink, which will react very fast -- but disfavored because it means you're eating a lot of sodium. Calcium carbonate is generally insoluble, so it works slower, but it does dissolve in acid solution, and you're not eating a lot of sodium. The result of either chemical reaction is CO2 gas, which is what makes you burb. The chemical reaction is readily understandable at the high school level.

(6) Does industry count? The history of limestone, lime, concrete and mortar is fascinating, going all the way back to the Romans, who built extensively in concrete. You roast limestone (CaCO3) which releases CO2 and produces lime (CaO). The lime is "slaked" with water, producing Ca(OH)2. When this is mixed with sand it makes mortar, which can be easily troweled on, but after exposure to air it slowly re-absorbs CO2 and recreates the original limestone -- which is what cured mortar is. It's basically a way of turning rock into a spreadable liquid and then letting it turn back into rock again.

(7) How about fermentation and the production of alcoholic beverages, like wine and beer? Yeast oxidizes glucose to ethanol and CO2 (which is where the bubbles come from), but ethanol exposed to air long enough continues to oxidize to ethanal (acetaldehyde) and on to ethanoic acid (acetic acid), also known as vinegar. It's interesting that our word "acid" comes from the Latin "acetum" which means "vinegar." (In fact, the literal translation of "acetic acid" is "acid acid.") Furthermore, when the further oxidation takes place in the human liver, the ethanal is quite toxic, much more so than either the ethanol or the acetic acid -- and it is this that contributes strongly to the "hangover." Finally, people who have been poisoned by drinking methanol can be detoxified -- by keeping them drunk! The ethanol interferes with the breakdown pathway that produces extremely toxis formaldehyde out of methanol, so that the methanol is broken down by safer but slower pathways.

(8) Sunscreens. The oldest and most purely effective is zinc oxide, a compound that absorbs strongly in the ultraviolet but not in the visible, which makes it white but very UV absorbent. More popular sunscreens for people who don't want to look like they've painted themselves white are PABA and derivatives, which have benzene rings that have good UV absorption, but transparency to visible.

(9) Batteries, of course. A whole subject in itself.

(10) The production of polymers is fascinating. The role of nylon-66 in "winning the war" (WW2) by replacing silk in parachutes is an interesting story. The man who invented nylon, Wallace Carothers, is a fascinating if morbid story: he was deeply troubled, and just after inventing nylon (and in part due to his sister's untimely death) he committed suicide in a true chemist fashion, by drinking cyanide. His invention turned Dupont from a gunpowder company into a plastics and chemicals company, which it remains. Another fascinating aspect of polymers is how their properties are determined by how they are made: for example mylar is made by blowing PET (the stuff from which soda bottles are made) into giant building-sized balloons. The stretching of the polymer chains to align with the surface of the balloon makes the plastic very resistant to tears. Similarly, Kevlar is drawn from the liquid through tiny holes, and the tiny holes line the stiff Kevlar molecules up along the axis of the thread, making extremely tough fibers.

(11) The story of aluminum, and how it got to be so cheap we can make foil out of it and throw it away after one use is interesting. Napoleon supposedly kept a set of aluminum dishes for his most distinguished visitors, the regulars having to do with gold and silver, that being how expensive pure aluminum once was. Yet aluminum is the third most common element on the Earth's crust. It's just so tightly bound to oxygen, usually, that it is very hard to reduce to the pure metal. The invention of the Hall-Heroult process revolutionized the use of aluminum. It's an interesting human story, too, because Hall was an amateur, and made his discovery working in his garage, with a saucepan and stove.

If you have time, there are plenty of small books on this kind of stuff available at Amazon and so forth. Look for chemistry of consumer goods, or in every day life.

Answer 4

thanks @Carl_Pham ..extremely helpful