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A lead storage battery has initially 200 g of lead and 200 g of PbO2 plus excess H2SO4. Theoretically, how long could this cell deliver a current of 10.0A, without recharging, if it were possible to operate it so that the reaction goes to completion? (Pb = 208)

A.16083.33 s
B.8041.67 s
C.44.68 s
D.18557.7s

1 Answer

4 votes

Final answer:

By applying Faraday's law, we calculate that a lead storage battery with 200 g of lead and 200 g of PbO₂ could theoretically deliver a current of 10.0 A for approximately 18557.7 seconds before needing recharging.

Step-by-step explanation:

The question asks how long a lead storage battery could deliver a current of 10.0 A using 200 g of lead and 200 g of PbO₂. To solve this, we need to consider the electrochemical reaction taking place in the battery and apply Faraday's law of electrolysis. The relevant chemical reaction at the electrodes during discharge is:

Pb(s) + PbO₂(s) + 2H₂SO₄(aq) → 2PbSO₄(s) + 2H₂O(l).

Lead has a molar mass of 208 g/mol, so we can convert the mass of lead and PbO₂ to moles:

  • 200 g of Pb ≈ 200 g / 208 g/mol ≈ 0.96 moles.
  • Since Pb and PbO₂ react in a 1:1 molar ratio, Pb limits the reaction amount to 0.96 moles.

To find the total charge Q moved, we use:

Q = n * F, where n = number of moles of electrons, F = Faraday's constant (96,485 C/mol).

For every mole of Pb used, two moles of electrons are involved; hence n = 0.96 moles * 2.

Q = 0.96 moles * 2 * 96,485 C/mol ≈ 185,530 C.

Current (I) is the charge moved per unit time (t). I = Q/t or t = Q/I.

To find the time t:

t = 185,530 C / 10.0 A ≈ 18,553 s, which is option D, 18557.7 seconds.

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