# What is the percentage composition of a compound containing 32.0 g of bromine and 4.9 g of magnesium?

Mar 18, 2016

The percent composition of bromine is 86.7%, and the percent composition of magnesium is 13.3%.

#### Explanation:

In order to determine the percent composition of an element in a given sample of a compound, divide the mass of the element in the sample by the total mass of the sample and multiply by 100.

The given compound is magnesium bromide $\left(\text{MgBr"_2}\right)$. The total mass of the sample of $\text{MgBr"_2}$ is:

$\text{32.0 g Br+4.9 g Mg"="36.9 g MgBr"_2}$.

% "composition Br"=(32.0 cancel"g")/(36.9 cancel"g")xx100="86.7%"

% "composition Mg"=(4.9 cancel"g")/(36.9 cancel"g")xx100=13.3%"

Check: 86.7%+13.3%=100.0%