When a lead acid car battery is recharged by the alternator, it acts essentially as an electrolytic cell in which solid lead(II) sulfate PbSO4 is reduced to lead at the cathode and oxidized to solid lead(II) oxide PbO at the anode. Suppose a current of 17.0A is fed into a car battery for 15.0 seconds. Calculate the mass of lead deposited on the cathode of the battery. Be sure your answer has a unit symbol and the correct number of significant digits.

0.273504 grams

Explanation:

Charge Deposited = Current ×Time

q=It

Given: I= 17.0A, t= 15.0 seconds

Q= 17×15= 255 C

Since, 1 mole contains 96500C of charge deposition

Therefore, number of moles = 255/96500 = 0.00264 moles

Moreover, since Pb changes to Pb2+,

Hence number of moles of Pb deposited = 0.00264/2

= 0.00132

Also, Molar mass of Lead = 207.2 gm/mol

Therefore, the mass of lead deposited = 0.00132×207.2 = 0.273504 grams

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answer: c.

explanation:

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !