Question

Calculate the weight of Hydrogen gas which occupy a volume 3.36 dm³ at STP.

Answer 1

• The given volume of Hydrogen gas(H₂) =3.36 dm³ = 3.36 L
• We know that 1 mole of Hydrogen gas(H₂) = 6.022 × 10²³ molecules = 22.4L volume at STP
• Use the unitary method to calculate the number of moles of hydrogen gas for the given volume,

22.4 L volume of Hydrogen gas(H₂) has a number of moles= 1 mol

Then, 1 Litre volume of Hydrogen gas(H₂)has a number of moles = $\frac{1}{22.4}$

Therefore 3.36 L of hydrogen gas (H₂) has a number of moles = $\frac{1}{22.4}$× 3.36 = 0.15 moles.

• 1 mole of hydrogen gas(H₂) has weight = Molecular weight of Hydrogen gas(H₂)= 2 g

There fore 0.15 mole Hydrogen gas(H₂) has weight = 0.15 × 2 = 0.3g

Thus the weight of Hydrogen gas(H₂) which occupy a volume of 3.36 dm³ at STP is 0.3g.