# Electrochemistry Question: Calculation

1. Dec 5, 2011

Hi there, this might be a rather elementary topic but here goes.....

1) An electrolytic circuit using graphite electrodes and sulfuric acid as the electrolyte is set up.

One of the gases (A) is more than twice the volume of the other (B). Volume of B is taken as 10 cm3. It is found that vol. of A is 2.5 cm3 greater than what is expected. With appropriate equations, suggest why this is so.

I'm really not sure on this one. Did the hydrogen react with another substance?

2) 2 voltaic cells: Cell A using Mg and Cu and Cell B using Zn and Cu is set up. Electrolyte used is dilute sulfuric acid.

(a) Assuming rate of current is same for both cells, which cell will have a greater loss in mass at one of the electrodes and why?

My Attempt: Cell B ( I don't know why. )

(b) Calculate the loss in mass of the electrote in cell B when the loss in mass in cell A is 1.2g.

My attempt: No. of moles of Mg lost = 1.2/24.3 = 0.4938271
Hence, mass of Zngained is: 0.4938271 x 65.4 = 32.29629

My answers are quite feeble attempts and they're most probably wrong. I would like someone to explain. Thanks in advance!