electrolysis problem? HELP!!!!1?

Question

OK, I have an AP Chem test tomorrow, and I stumbled across this problem; i need help ASAP!

The electrolysis of .100L of .785 M AgNO3(aq) using platinum electrodes is carried out with a current of 1.75 A. What is the molarity of the AgNO3 25.0 min after electrolysis has begun?

Answer 1

if you know how much silver has been removed, you can easily work out how much is left, and so you can work out the concentration.

First, you need to work out how much electric charge is passed:

Charge (C) equals current (amp) x time (s)

Then you need to divide the charge by Faraday's constant, to find out how many Faradays have been passed. Remember that at Faraday is a mole of electrons.

Silver in solution is Ag+

So each Faraday will remove just 1 mol.

You had 0.100 L x 0.785 mol/L = 0.0785 mol to start with.

Take away what has been removed by electrolysis.

Remember that the amount remaining is dissolved in 0.100 L, and you can work out your answer.