ElectrochemistryHard
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 solution was 1 L. Identify the correct statement(s):
Options
A.The overall cell reaction is: Pb(s) + PbO2(s) + 2H2SO4(aq) → 2PbSO4(s) + 2H2O(l).
B.A total of 2.0 moles of H2SO4 is reacted.
C.The total charge released from anode of the cell is 1.93 × 105 coulomb.
D.The mass of electrolytic solution has decreased.
Solution
Net cell reaction of discharge is
$Pb + PbO_{2} + \underset{x\text{ mole}}{2H_{2}SO_{4}} \rightarrow 2PbSO_{4} + \underset{x\text{ mole}}{2H_{2}O}$
Initial mass of H2SO4,
$w_{1} = 1000 \times 1.26 \times \frac{40}{100} = 504\text{ gm}$
Final mass of H2SO4,
$w_{2} = (1260 - 98x + 18x) \times \frac{28}{100} = (352.8 - 22.4x)\text{ gm}$
From reaction, 504 – 98x = 352.8 – 22.4 x ⇒ x = 2
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