What is the mass of hydrogen in "72.0 g CH"_4"?

Aug 3, 2017

There are $\text{53.9 g C}$ and $\text{18.1 g H}$ in ${\text{72.0 g CH}}_{4}$.

Explanation:

The chemical formula for methane is ${\text{CH}}_{4}$. This means that in one mole of methane, there is one mole of carbon and four moles of hydrogen.

The molar mass of methane is $\text{16.043 g/mol}$, which means that one mole of methane has a mass of $\text{16.043 g}$.

The molar mass of carbon is $\text{12.011 g/mol}$, which means that one mole of methane contains $\text{12.011 g C}$.

In order to determine the mass of carbon in $\text{72.0 g CH"_4}$, multiply the given mass of methane by the inverse of its molar mass to get moles $\text{C}$, then multiply by the molar mass of carbon in methane to get mass of $\text{C}$.

72.0color(red)cancel(color(black)("g CH"_4))xx(1color(red)cancel(color(black)("mol CH"_4)))/(16.043color(red)cancel(color(black)("g CH"_4)))xx(12.011"g C")/(1color(red)cancel(color(black)("mol CH"_4)))="53.9 g C"

In order to determine the mass of hydrogen in $\text{72.0 g CH"_4}$, subtract the mass of carbon from the given mass of methane.

$\text{72.0 g CH"_4-"53.9 g C"="18.1 g H}$