How many molecules are present in 33.22 liters of methane gas (CH4) at STP?

Answer 1

At STP, 1 mole of a gas occupies a volume of 22.4 L. First, setup a proportion to determine the moles of methane gas in 33.22 L.

1 mol = 22.4 L

? mol = 33.22 L

? = (33.22 L x 1 mol / 22.4 L) = 1.483 mol CH₄

Next, use avogadro's # to convert moles to molecules.

1.483 mol CH₄ x (6.02 x 10²³ molecules CH₄ / 1 mol CH₄) = 8.928 x 10²³ molecules CH₄