Question

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

Answer 1

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 `("MgBr"_2")`. The total mass of the sample of `"MgBr"_2"` is:

`"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%`