A spot test for gold has been in use for decades. The sample is first treated with nitric acid. Other metals may react or dissolve in this acid, but gold will not. Then the sample is added to a mixture of nitric acid and hydrochloric acid. Gold will only dissolve in this mixture. The term "acid test" arose from the California gold rush in the late 1840"s when this combination was used to test for the presence of real gold. It has since come to mean, "tested and approved" in a number of fields.
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An acid can be defined in several ways. The most straightforward definition is that an acid is a molecular compound that contains one or more hydrogen atoms and produces hydrogen ions (left( ceH^+ ight)) when dissolved in water.
An oxyacid is an acid that consists of hydrogen, oxygen, and a third element. The third element is usually a nonmetal.
a. Oxyanions with -ite ending.
The name of the acid is the root of the anion followed by the suffix -ous. There is no prefix.
b. Oxyanions with -ate ending.
The name of the acid is the root of the anion followed by the suffix -ic. There is no prefix.
Writing Formulas for Acids
Like other compounds that we have studied, acids are electrically neutral. Therefore, the charge of the anion part of the formula must be exactly balanced out by the (ceH^+) ions. Another way to think about writing the correct formula is to utilize the crisscross method, shown below for sulfuric acid.