A definite mass of `CO_2` gas at STP has a volume of 67.2 Litre in a cylinder.
a) Calculate the mass of `CO_2` (Atomic mass, C - 12, O =16)
b) Calculate the number of molecules of `CO_2` in the cylinder.

Explanation

a) Molecular mass of `CO_2`
= ` 12 xx 1 + 16 xx 2 = 12 + 32 = 44`
Number of moles of 67.2 L `CO_2` at STP
=(67.2L/22.4L) = 3
Mass of 3 mole `CO_2` + ` 3 xx 44` = 132g
`3 xx 6.022 xx 10^23`