Question

A gas has an empirical formula CH4. 0.16g of the gas occupies a volume of 240cm^3 What is the molecular formula of the gas???.

Help me anyone who know!!!​

Answer 1

Explanation and answer:

The molar volume of a gas is 22.4 L at 0 deg. C.

So the molar mass of the gas is, by proportion,

0.16 g * (22400 mL)/(240 mL) = 14.93 g

The molar mass of (CH4)n = 12+4(1) = 16.

So n = 15.93/16 = 1, or the molecular formula is CH4.

Note: The temperature at which the volume was observed was not given. If 240 cm^3 was observed at 20 deg.C, then the volume at 0 deg.C would be

V=240*(273+0)/(273+20) = 223.6

The molar mass = 0.16*22400/(223.6) = 16.03

which gives n = 16/16.03 = 1 again, but more accurately.