We’re being asked **to give the percent composition of chlorine** of in cobalt(II) chloride hexahydrate

The **mass percent formula** is shown below:

$\overline{){\mathbf{mass}}{\mathbf{}}{\mathbf{percent}}{\mathbf{=}}\frac{\mathbf{mass}\mathbf{}\mathbf{component}}{\mathbf{total}\mathbf{}\mathbf{mass}}{\mathbf{\times}}{\mathbf{100}}}$

**Step 1: Determine the molecular formula: **

The **rules ionic compounds** are as follows:

1. The metal keeps its name and is named and written first.

– For transition metals, we use Roman numerals to denote its charge

2. The nonmetal keeps its base name but has its ending changed to **–ide**.

3. Hydrate is H_{2}O with written alone with the numerical prefix.

What is the percent composition of chlorine in cobalt(II) chloride hexahydrate?

A. 29.8% B. 24.8% C. 47.9%

D. 39.8% E. 54.6%