# What is the volume in liters of 6.75*10^24 molecules of ammonia gas at STP?

Oct 16, 2016

$255 L$ (3 s.f.)

#### Explanation:

To go from molecules to volume, we need to convert to moles. Recall that one mole of a substance has $6.022 \cdot {10}^{23}$ molecules (Avogadro's number).

Moles of ammonia gas:

$\frac{6.75 \cdot {10}^{24}}{6.022 \cdot {10}^{23}} = 11.2089 \ldots$moles

At STP, the molar volume of a gas is $22.71 L m o {l}^{-} 1$. This means that per mole of a gas, there are 22.71 litres of the gas.

Volume of ammonia gas:

$11.2089 \ldots \cancel{m o l} \cdot \frac{22.71 L}{\cancel{m o l}} = 254.55 L$