In a classroom demonstration of a redox reaction, Professor Smith set up a voltaic cell with a copper metal anode and a silver metal cathode. The two electrodes were in contact with solutions of the corresponding metal ions, Cu²⁺ and Ag⁺. During the illuminating lecture on redox chemistry, the crystals of silver metal deposited on the silver electrode as the copper solution turned a darker blue. The added silver crystals had a mass of 2.68 g after 50.0 minutes of lecture. What was the average current that the cell produced?

Question

Quizplus · Accepted Answer

To find the current produced by the cell, we need to use Faraday's law, which states that the amount of substance produced or consumed in an electrochemical reaction is directly proportional to the amount of charge transferred. The formula is:

moles of substance = (current x time) / (n x F)

where n is the number of electrons transferred in the balanced redox equation and F is Faraday's constant.

In this case, the balanced redox equation is:

Cu2+ + 2e- → Cu (anode: oxidation)
Ag+ + e- → Ag (cathode: reduction)

n = 2 for Cu and 1 for Ag.

We can calculate the moles of silver deposited on the cathode as:

moles of Ag = mass / molar mass = 2.68 g / 107.87 g/mol = 0.0248 mol

The charge transferred can be calculated by multiplying the number of moles of electrons transferred:

charge = n x moles of Ag x F = 1 x 0.0248 mol x 96,485 C/mol = 2,395 C

Finally, we can find the average current as:

current = charge / time = 2,395 C / 3,000 s = 0.799 A (or 0.80 A to two significant figures)

Therefore, the answer is A) 0.799 A.

In a Classroom Demonstration of a Redox Reaction, Professor Smith