602 MAN IS MASTERING HIS MATERIAL WORLD form hydronium ions are also termed acids, although they might better be termed acid-formers. There are three general types of acid-formers: \. Hydrides of nonmetals or nonmetallic radicals. Examples, HCl, H(CoH302). A hydride is a compound of an element or a radical with hydrogen, HCl + H2O — hydrogen chloride HC2H3O2 + hydrogen acetate water H2O water (H30)+, CIhydronium ion chloride ion -^ (H30)+, (C2H3O2)- hydronium ion acetate ion 2. Oxides of nonmetals or nonmetallic radicals. Examples, CI2O3, (C>H30)20. CI2O3 + 3 H2O chlorine trioxide water (C2H30)20 + 3 H2O acetyl oxide (acetic anhydride) water hydronium ion 2(H30+), hydronium ion chlorite ion -^ 2(H30+), 2(C102)- 2(C2H302)- 3. Hydroxides of nonmetals or nonmetallic radicals. P(0H)3', S02(OH)2. P(0H)3 + Examples,
PROTON CHEMISTRY: ACIDS AND BASES 603 An Acid Is a Proton-donor. The characteristic chemical reactions of acids are given as follows: 1. Acids react with metals such as sodium, that have a smaller attraction for electrons than hydronium ions have, to give hydrogen gas. I loses an electron 4- 2(H30)+, CI + Na —>- Na+, CI" + H2 + H2O hydrochloric acid sodium sodium chloride hydrogen water I gains an electron t This reaction is obviously an example of a displacement type of electron transfer. 2. Acids react with ammonia, NH3. (H30)+, CI- + NH3 —> (NH4)+, CI- + H2O hydrochloric acid ammonia ammonium chloride water In this reaction the hydronium ion, to ammonia, NH3. (HsO)^, gives up a proton, H+, 3. Acids react with bases. Bases are recognized by their characteristic properties ; a base is a substance whose water solution feels slippery, tastes bitter or alkaline, changes the color of indicators to a color different from tJiat produced by acids, and neutralizes acids to form salts. Some common bases are: the weak base, ammonium hydroxide, NH4OH, a 3 per cent solution of which is the ordinary household aqua ammonia; the strong base, sodium hydroxide, NaOH, which is commonly known as soda lye; the strong base, potassium hydroxide, KOH, known as potash lye; and the mild base, calcium hydroxide, Ca(0H)2, known as hydrated lime, which is used in making mortar and plaster. Strong bases, such as sodium hydroxide and potassium hydroxide, are called alkalies, because they are prepared from hydroxides of the alkali metals. In the reaction of hydrochloric acid with sodium hydroxide, it is evident that the hydronium ion, (HsO)"^, gave up a proton, H+, to the hydroxyl ion, (OH)-, to form water. (H30)+, CI + Na+, (OH)- —>- 2 H2O + Na+, CI" hydrochloric acid sodium hydroxide water sodium chloride (acid) (base) (salt) In the reactions of hydrochloric acid with ammonia and with sodium hydroxide, the fundamental reaction was that in which hydronium ions gave up protons to another substance. Inasmuch as this property of giving up protons to other substances is characteristic of acids only, acids are called proton-donors.