Question

What is the structural formula of calcium propanoate?

Answer 1

The formula of calcium propanoate is ("CH"_3"CH"_2COO)_2"Ca"#.

Explanation:

You can tell from the name that this is the calcium salt of propanoic acid.

The formula of propanoic acid is `"CH"_3"CH"_2"COOH"`, so the propanoate ion is `"CH"_3"CH"_2"COO"^(-).`

Calcium is in Group 2, so calcium ion is `"Ca"^(2+)`.

It takes two propanoate ions to balance the charge of one calcium ion, so the formula of calcium propanoate is `("CH"_3"CH"_2"COO")_2"Ca"`.

Note the exception: The salts of carboxylic acids usually have the metal ion written last.

`"Ca"("CH"_3"CH"_2"COO")_2` is acceptable, but `("CH"_3"CH"_2"COO")_2"Ca"` is preferred.