# Question #38149

#### Answer:

The formula must be written ${\left(N {H}_{4}\right)}_{2} S {O}_{4}$ because ammonium sulfate is an ionic compound.

#### Explanation:

Ionic compounds combine positively charged ions (cations) with negatively charged ions (anions).

The resulting compound will be electrically neutral - that means the compound has an overall charge of zero.

The ammonium ion ($N {H}_{4}^{+}$) has a charge of +1, so you need to have two of them to balance the charge of the sulfate ion ($S {O}_{4}^{-} 2$) which has a charge of -2.

This video discusses how to determine the chemical formula for some additional examples of ternary ionic compounds. The video discusses how to write formulas for; lithium hydroxide, magnesium nitrate and aluminum sulfate.

Hope this helps!