Urgent help needed

[VCAA Official]

I'm terribly confused. My teacher just told me that any time yu change the cathode material, like graphite to iron yu do nt change the end products formed (as in, the cathode will never 'react' with the electrons and instead will go to the solution you are electrolysing). I don't get this! wuldn't we have t refer to the electrchemical series t determine this?

He says that if you change the anode then there will be a change in products thugh always! I don't get this!! he said something about metals too, are metal andes the only ones these rules apply too? why is that? and again, hwo come no refering to the electrochemical series?

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and I got this question:
An alkaline cell contains 20g Mn03 which produces a current at a coltage of 1.5 V. Calculate the elevtrical energy produced by the cell.

-how do you go that questin? I have zero idea.

the second part is:

if 1 mA of current is produces what is the cell life of the cell -I have equallly no idea!

can you help me? how are these questions done?

We are given the reaction that occurs in an alkaline cell (in actual VCAA exams will they give us this reactin - the 2MNO2 one?) or do we have to memorise them.

thanks

[chansthename]

The cathode is where there will be reduction of whatever is in the electrolyte ONTO the cathode, it does not react, therefore when you change what the cathode is made of you will still get a buildup of the same chemical. Think electroplating, you might be doing it with a bed-frame or jewellery, you would put it at the cathode and just electroplate using the electrolyte.

[MBBS]

Yes, reduction occurs at the cathode and oxidation at the anode. So the rod that is the cathode will get smaller.