Acids are sticky things -- they cling to each other and hardly break ranks. The reason why is called "hydrogen bonding." Alcohol loosens up acids, making them leave their own. Acids do bond with alcohols, but the combination is volatile esters.** That leads to flying apart.
Volatility --> wings --> nose (aroma).
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*The metaphor dates from (at least) Lord Kelvin. See my discussion here.
**The word "ester" is pure invention, without metaphor: link
Showing posts with label Acids. Show all posts
Showing posts with label Acids. Show all posts
Tuesday, May 8, 2018
Tuesday, August 31, 2010
The Basics Of How Chemistry Is Like Sex
Anyone who has cleaned with Windex has whiffed ammonia, a substance with a rich and interesting history that includes its very name: link. Note that ammonia was once called animal alkali. Muslims-in-science scholars should take note of the origin of the word alkali, but should take care not to get the concept of alkaline bases etymologically confused with that other Arabic word meaning base.
Ammonia gas easily condenses into a liquid when compressed (Albert Einstein and his erstwhile student Leó Szilárd once patented a refrigerator with no moving parts that used ammonia instead of freon). If Szilárd's idea had gone anywhere, he may not have bothered to have conceived the atomic bomb.
Ammonia has been variously depicted as NH3 or better as :NH3 or better still with its electron "lone pair" on full display, as:
Ammonia gas easily condenses into a liquid when compressed (Albert Einstein and his erstwhile student Leó Szilárd once patented a refrigerator with no moving parts that used ammonia instead of freon). If Szilárd's idea had gone anywhere, he may not have bothered to have conceived the atomic bomb.
Ammonia has been variously depicted as NH3 or better as :NH3 or better still with its electron "lone pair" on full display, as:
The lobe-like appendage sticking up is called a "lone pair" because there are two electrons in the orbital and because they're not associated with any atom except nitrogen. Some depictions of ammonia omit the lone pair but here I prefer the "fig leaf is off" depiction.
Ammonia is perpetually in search of an acid to quench its baser instincts. Given a proton like H+, ammonia and the proton instantly couple to make ammonium NH4+ in which all four H's become equivalent. In a real sense, the incoming acid polarizes the other three H's, sucking electrons away from them, making them all more acidic.
Ammonia is perpetually in search of an acid to quench its baser instincts. Given a proton like H+, ammonia and the proton instantly couple to make ammonium NH4+ in which all four H's become equivalent. In a real sense, the incoming acid polarizes the other three H's, sucking electrons away from them, making them all more acidic.
Labels:
Acids,
alchemy,
Chemistry is like sex,
Hydrogen,
hypothesis,
nitrogen
Acerbic Wet
The Danes and the Brits pioneered graphic depictions of simple chemical reactivity. Brønsted and Lowry independently shocked early 20th century chemists with their notions of spontaneous self-ionization of water:
Brønsted-Lowry theory explains how even the purest distilled water conducts electricity (which requires something charged). In their scheme, one water acts like a base by accepting a proton, while the other one acts like an acid, donating a proton. The slight but measurable extent of such H-swapping is real enough--a normal glass of water has a measurable concentration of H3O+ of about 10-7 units or a pH of 7 (pH is like a Richter scale). An equal & countervailing amount of hydroxide, OH- neutralizes the acid.
Now consider adding anything to that glass of water which increases the amount of H3O+ (but not OH-). Such a thing which donates an H+ to a neutral water molecule is called an acid in English. The Germans call them Säure, which is related to our word sour. Svante Arrhenius (the august savant who also thought up AGW), came up with the idea first.
Brønsted-Lowry theory explains how even the purest distilled water conducts electricity (which requires something charged). In their scheme, one water acts like a base by accepting a proton, while the other one acts like an acid, donating a proton. The slight but measurable extent of such H-swapping is real enough--a normal glass of water has a measurable concentration of H3O+ of about 10-7 units or a pH of 7 (pH is like a Richter scale). An equal & countervailing amount of hydroxide, OH- neutralizes the acid.
Now consider adding anything to that glass of water which increases the amount of H3O+ (but not OH-). Such a thing which donates an H+ to a neutral water molecule is called an acid in English. The Germans call them Säure, which is related to our word sour. Svante Arrhenius (the august savant who also thought up AGW), came up with the idea first.
Labels:
Acids,
Chemistry,
Chemistry is like sex,
History of Chemistry,
Hydrogen,
oxygen,
protons
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