A lead storage cell is discharged which causes the H2SO4 electrolyte to change from a concentration of 40% by weight (density = 1.260 g/ml) to 28%, by weight. The original volume of electrolyte was 1

Question

A lead storage cell is discharged which causes the H2SO4 electrolyte to change from a concentration of 40% by weight (density = 1.260 g/ml) to 28%, by weight. The original volume of electrolyte was 1 L. Identify the correct statement(s):

Prashant Kotian · Accepted Answer

Correct answer: A,B,C,D. The cell reaction given in Option A is correct. Initial solution mass = 1000 × 1.260 = 1260 g, containing 504 g H2SO4. Let x moles of reaction occur. Mass of H2SO4 consumed = 196x g; water produced = 36x g. Final mass of solution = 1260 - 160x g. Final H2SO4 mass = 504 - 196x g. Using the final 28% concentration: (504 - 196x) / (1260 - 160x) = 0.28. Solving this yields x = 1.0 mole. Thus, 2x = 2.0 moles of H2SO4 reacted (Option B). One mole of reaction transfers 2 Faradays of charge = 2 × 96500 C = 1.93 × 10^5 C (Option C). The total mass of the solution decreases from 1260 g to 1100 g because sulfate ions are heavily deposited onto the electrodes as solid PbSO4 (Option D). Therefore, correct answer is A,B,C,D.

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