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In a lead-acid storage battery (accumulator), the discharge reaction is: Pb(s) + PbO2(s) + 2H2SO4(aq) -> 2PbSO4(s) + 2H2O(l). A current of 2.50 ampere is drawn continuously for 1930 minutes. Calculate the mass of H2SO4 (in grams) consumed during this discharge.
- 294 g
- 196 g
- 147 g
- 392 g
Correct answer: 294 g
Solution
Total charge Q = 2.50 * (1930 * 60) = 289500 C. Moles of electrons = 289500 / 96500 = 3.0 mol. Since 2 mol H2SO4 are consumed per 2 mol electrons, moles H2SO4 = 3.0 mol. Mass = 3.0 * 98 = 294 g.
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