SAT Subject Test Chemistry
REVIEW OF MAJOR TOPICS
Acids, Bases, and Salts
A salt is an ionic compound containing positive ions other than hydrogen ions and negative ions other than hydroxide ions. The usual method of preparing a particular salt is by neutralizing the appropriate acid and base to form the salt and water.
There are five methods for preparing salts.
Five methods for preparing salts are as follows:
1. Neutralization reaction. An acid and a base neutralize each other to form the appropriate salt and water. For example:
2. Single replacement reaction. An active metal replaces hydrogen in an acid.
Mg(s)+H2SO4(aq) → MgSO4(aq)+H2(g)
3. Direct combination of elements. An example of this method is the combination of iron and sulfur. In this reaction small pieces of iron are heated with powdered sulfur:
4. Double replacement. When solutions of two soluble salts are mixed, they form an insoluble salt compound. For example:
AgNO3(aq)+NaCl(aq) → NaNO3(aq)+AgCl(s)
5. Reaction of a metallic oxide with a nonmetallic oxide. For example: