Question

5.6 litres of gas Z weighs 32 g at STP. What is the molecular weight and vapour density of Z?

Answer 1

Given: 5.6 litres of gas Z weighs 32 g

According to Avogadro’s Law, one mole of any ideal gas occupies a volume of 22.4 L at Standard Temperature and Pressure (STP).

Formula: Number of moles (n) = `("Volume")/"Molar Volume at STP"`

= `5.6/22.4`

= 0.25 moles

Molecular weight = `"Mass"/"Moles"`

= `32/0.25`

= 128 g/mol

Vapour density = `"Molecular Weight"/2`

= `128/2`

= 64