Question 13
Mole Concept and Stoichiometry10.0 dm3 of air containing H2S as an impurity was passed through a solution of Pb(NO3)2 until all the H2S had reacted. The precipitate of PbS was found to weigh 5.02 g. According to the equation: Pb(NO3)2 + H2S → PbS + 2HNO3 the percentage by volume of hydrogen sulphide in the air is [Pb = 207, S = 32, GMV at s.t.p = 22.4 dm3]
- A.50.2
- B.47.0
- C.4.70
- D.0.47
Show the answer and explanation
Answer: C (4.70)
Explanation
Moles of PbS = 5.02 ÷ 239 = 0.021, which equals moles of H2S. Volume = 0.021 × 22.4 = 0.470 dm3, which is 4.70% of 10.0 dm3.