Question

Question #e05a9

Answer 1

At STP, 13.0 L of methane has a mass of 9.18 g.

Explanation:

You will need the molar volume of a gas at STP

At STP of `"273.15 K"` and `"100 kPa"`, the molar volume of a gas is `"22.711 L/mol"`.

You will need to determine the moles of methane by dividing the volume in liters of methane by its molar volume at STP.

`13.0cancel"L CH"_4xx (1"mol CH"_4)/(22.711 cancel"L CH"_4)="0.57241 mol CH"_4"` (I am keeping some guard digits to reduce rounding errors.)

In order to determine the mass of 13 L of methane at STP, you will need to multiply the moles of methane times its molar mass.

Molar mass of `"CH"_4"` is `"16.04246 g/mol"`
http://pubchem.ncbi.nlm.nih.gov/compound/297#section=Top

`0.57241cancel"mol CH"_4xx(16.04246"g CH"_4)/(1cancel"mol CH"_4)="9.18 g CH"_4"` (rounded to three significant figures)