Question

What volume will 35.9 g of hydrogen gas (H2) occupy at STP?

Answer 1

35.9g x 1 mol/ 2.016g x 22.4 L/ 1 mol= 398.89 L

Answer 2

Answer: 402.08 L

Explanation: According to avogadro's law, 1 mole of every substance occupies 22.4 Liters at STP and contains avogadro's number $6.023\times 10^{23}$ of particles.

To calculate the moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}$

$\text{Number of moles}=\frac{35.9 g}{2g/mol}=17.95moles$

Now 1 mole of $H_2$ molecule occupy= 22.4 L at STP

17.95 moles of $H_2$ molecule contains = $\frac{22.4}{1}\times 17.95=402.08 L$ at STP