Question

48
Review
A sample of dilute H2SO4 of purity
40% (by volume) and 50 mL of this acid
solution was allowed to react with
Zn. The volume of H2 gas in litres
liberated at 1 atm and 273 K is
(Density of pure H,SO, is 1.3 g mL-1)​

Answer 1

Given:

• The percentage purity by volume of a sample of H₂SO₄ is 40%
• Volume of the sample reacted (v) is 50 mL
• Density of H₂SO₄ (d) is equal to 1.3 g/mL
• Molar of H₂SO₄ (Mm) is 98g/mol

To find:

The volume of hydrogen gas liberated at 1atm and 273K, i.e. at STP

Solution:

• The volume of pure H₂SO₄ (v1) is 40% of 50 mL = 20 mL
• The mass of H₂SO₄ reacted (m) is equal to (v1*d) = 26 g
• Moles of H₂SO₄ is m/Mm = 26/98
• One mole of H₂SO₄ on reaction with zinc produces one mole of hydrogen gas.So, moles of hydrogen gas equals 26/98
• One mole of any gas occupies 22.4L of volume at STP. So, the volume occupied by 26/98 moles equals 26/98*22.4 = 5.94L

Answer:

The volume of hydrogen gas liberated at 1atm and 273K, i.e. at STP is equal to 5.94L