# Question #20ba9

Nov 8, 2016

$8.30 \times {10}^{22}$ molecules.

#### Explanation:

one mole of molecules is avogardo's number of molecules. This equals $6.02 \times {10}^{23}$ molecules

At STP one mole of an ideal gas occupies 22.4 liters.

So to find the number of moles divide the volume at STP by the molar volume at STP This gives

$\frac{3.09}{22.4} = 0.138$ moles

Now to find the molecules multiply the number of moles by the number of molecules per one mole

$0.138 \times 6.02 \times {10}^{23} = 8.30 \times {10}^{22}$ molecules.