Question

The mass of 112 litres of ${\text{CH}}_4$ at STP is

• A. 160 g
• B. 80 g
• C. 40 g
• D. 60 g

Answer 1

The correct option is B 80 g

Given: Volume of methane = 120 litres
Molar volume at STP (litres) = 22.4 L
Gram molecular mass of methane = 16 g
In case of gases at STP,
Mass = $\frac{\text{Volume at STP (litres)}}{\text{Molar volume at STP (litres)}}\times \text{Gram molecular mass}$

Now after inserting the values of volume at STP, molar volume at STP (litres) and gram molecular mass in the above equation, we get
Mass = $\frac{112}{22.4}\times 16$ = 80 g