# Naming salts

are by , including , and metal .

## Reactions with bases, including alkalis

Metal oxides are bases. In general, when an acid reacts with a metal oxide, the products are a and water.

Acid + metal oxide → salt + water

For example:

Sulfuric acid + copper oxide → copper sulfate + water

H2SO4(aq) + CuO(s) → CuSO4(aq) + H2O(l)

Alkalis are soluble bases. A salt and water are produced when acids react with alkalis. In general:

Acid + alkali → salt + water

For example:

Nitric acid + sodium hydroxide → sodium nitrate + water

HNO3(aq) + NaOH(aq) → NaNO3(aq) + H2O(l)

## Reactions with carbonates

A salt, water and carbon dioxide are produced when acids react with carbonates. In general:

Acid + carbonate → salt + water + carbon dioxide

For example:

Hydrochloric acid + copper carbonate → copper chloride + water + carbon dioxide

2HCl(aq) + CuCO3(s) → CuCl2(aq) + H2O(l) + CO2(g)

## Naming salts

The name of a salt has two parts. The first part comes from the base, alkali or metal carbonate. The second part comes from the acid:

• hydrochloric acid produces chloride salts
• nitric acid produces nitrate salts
• sulfuric acid produces sulfate salts
Question

Predict the name of the salt formed when copper oxide reacts with nitric acid.

The salt formed is copper nitrate.

## Deducing the formulae of salts

A salt has no overall charge, since the sum of the charges on their is equal to zero. The of some common ions are given below:

Charge on ionExamples
+1K+, Na+, Li+
+2Mg2+, Ca2+, Cu2+, Fe2+
+3Al3+, Fe3+
-1Cl-, Br-, I-, NO3-
-2SO42-
-3PO43-

Notice that ions of group 1 elements have a charge of +1, and ions of group 2 elements have a charge of +2. The group 7 element ions have a charge of -1, and the group 6 element ions have a charge of -2.

### Example

What is the formula of aluminium sulfate?

The formulae of the ions are Al3+ and SO42-.

The sum of the charges on the ions in the neutral salt must be zero. Two Al3+ ions have a total charge of +6 and three SO42- ions have a total charge of -6.

So the formula is Al2(SO4)3.

Question

What is the formula of magnesium chloride?

MgCl2