# How many moles of methane CH_4 are there in 80 grams of methane?

Dec 29, 2016

$5 \cdot m o l$ of methane are present in this mass..........

#### Explanation:

To find the number of moles, all we have to do is use the following relationship:

$\text{Number of moles}$ $=$ $\text{Mass"/"Molar mass}$

And the molar mass of methane may be read straight off your Periodic Table:

$\text{Molar mass of methane, } C {H}_{4} = \left(12.011 + 4 \times 1.00794\right) \cdot g \cdot m o {l}^{-} 1$

$\text{Mass"/"Molar mass}$ $=$ (80*cancelg)/(16.0*cancelg*mol^-1)=??mol.

Note that this calculation is consistent dimensionally:

$\frac{1}{m o {l}^{-} 1} = \frac{1}{\frac{1}{m o l}} = m o l$