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Acid-Base Properties of Salt Solutions:

• an ionic compound made of a cation and an anion, other than hydroxide.

• the product besides water of a neutralization reaction

A QUICK Tip to determine acidity or basicity of a salt:

1. Write the neutralization reaction in reverse (salt and water makes base and acid).

2. Break up the salt into its ions.

3. To write the base, add an OH^- to the cation (the positive ion) for each + charge.

4. To write the acid, Add H⁺ to the anion (the negative ion) for each negative charge.

5. If you for a strong base, the salt is basic.  (NaOH, KOH, LiOH, Mg(OH)_{2 ...}etc.)

    If you form a strong acid it is acidic.  (HCl, HNO₃, HClO₄, HBr...)

    If you form both a strong acid and a strong base it is neutral.

EXAMPLES

SODIUM ACETATE                                  NaC₂H₃O₂

NaC₂H₃O₂  + H₂O ==> NaOH + HC₂H₃O₂

Na⁺  + C₂H₃O₂^-  + H₂O ==> Na⁺ + OH^- + HC₂H₃O₂

Since NaOH is a strong base it breaks up and yields OH^-, the salt is basic.

HC₂H₃O₂ is a weak acid and will form (does not break up in water).

AMMONIUM CHLORIDE         NH₄Cl

NH₄Cl + H₂O<=> NH₄OH + HCl

Since HCl is a strong acid it breaks up and yields H⁺, the salt is acidic.

NH₄⁺  + Cl^- + H₂O<=> NH₃ +H₂O + H⁺ + Cl^-

NH₄OH is a weak base. They generally stay together, however this is actually breaks down into ammonia and water.

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