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First topic of this group! Anyone able to explain electrolysis? Its confusing for me when it comes to purifying copper and electrolysing brine, as I find it difficult to remember how it works.

Posted: 20-12-09 16:40 by I P B

Erm... I'll try my best, but sorry if it doesn't help...

Electrolysis is fairly simple when you understand it; it is basically the decomposition of ionic substances, so they are charged. For electrolysis to work properly, the electrolyte has to be molten or aqueous, so that the ions are free to move, and so that it is easier to split up.

In electrolysis, there are 2 electrodes; negative - (cathode) and positive - (anode), and they attract the oppositely charged ions - (i.e. positive ions to the cathode and the negative ions to the anode). The ions that are attracted to the positive electrode are said to be reduced as they receive electrons, the ions that are attracted to the negative electrode are said to be oxidised as they loose electrons (confusing, I know lol)

Posted: 22-12-09 21:31 by RATM33

Wow, that makes a lot of sense thanks! Apart fro mthat weird reduction oxidation thingy XD do you understnad half equations fby any chance? Because for some reason I have two different text books and they both have different ones for the purification of copper??

Posted: 22-12-09 21:41 by I P B

Purifying Copper

Copper is vital, as it is an excellent conductor and is used in electrical wiring, and the purer the copper, the better the conductor. Therefore, efficient purification of copper is imperative.

The cathode consists of pure copper, whereas the anode is made of impure copper. The electical supply makes the Cu2+ ions dissolve into the solution (sorry about the terrible wording), and these positive Cu2+ ions are attracted to the negative cathode. Any impurities are left at the anode, and are depositied at sludge.

Half equations - at the cathode - Cu2+ (aq) + 2e- > Cu(s)

- at the anode - Cu(s) > Cu2+ (aq) +2e-

Posted: 22-12-09 21:43 by RATM33

lol, soz that came out so wierd haha, i dont want to edit it in case i do anything wrong :S

Yh, I remember finding half equations hard asl when i did my C2 in june (seems like such a long time ago :P), but once you get the hang of them they arent that hard.

I dont know how to explain them to you...

erm.. tell me what you dont understand and i'll try my best

Posted: 22-12-09 21:46 by RATM33

Thats great, thankyou! It makes a lot of sense now. Electrolysing Brine makes sense now too. I am just wondering how we are meant to identify which products are produced if we are given any solution at all? I am not sure if we need to know any other solutions or not

Posted: 22-12-09 21:46 by I P B

No, im sure they wont give you any other solution apart from those 2, but they will ask you to balance half equations

Posted: 22-12-09 21:47 by RATM33

Is balancing half equations the same as balancing normal equations? Where the number of electrons have to make the whole neutral atom?

Posted: 22-12-09 21:50 by I P B

Yeah, kinda, but you have to make sure that the ions cancel each other out

eg - 2H+ + 2e- -> H2

As a hydrogen ion consists of only 1 proton, 2 electrons are added to balance it out to produce a hydrogen atom

In the exam, they’ll give you a data sheet, so that will help you

Posted: 22-12-09 21:56 by RATM33

Thats great, thankyou for all your help! Have you already sat your C2, B2, P2 exams?

Posted: 22-12-09 21:57 by I P B

yep, june 2009 :D

but, ive got my B3, C3 and P3, coming up in jan, so anything you need help with, just ask

what have you been predicted?

Posted: 22-12-09 21:59 by RATM33

Wow, good luck with those exams. I ahve been predicted A*s in all of them :( so I really need to try and work hard. I also have a problem where in my school we have left out pretty much all of the topics so I have to try learning them by myself, which is why I really appreciate your help :D so thankyou!

Posted: 22-12-09 22:01 by I P B

Yeah, I have as well, i got A* for chem and physics, but I got an A for biology - 88% soooo close lol, i was so dissappointed asl, coz i got A*s on my B1, C1 and P1

lol, same here, after the holidays, we got new teachers, who are rubbish lol, so I've bascially been left on my own to revise, anyhoo, good luck on your exams, dw, they wont be that hard **

Posted: 22-12-09 22:05 by RATM33

Wow those are really high grades well done! well thankyou very much! And please post topics even about Unit 3 if you want and we will do our best, tehre are other members who are probably doing the same as you who can help. thanks once again ***

Posted: 22-12-09 22:07 by I P B

Ooooooo, i was baout to ask someone about this topic as well...thanks RATM33 for the information it really is going to help me!!!!!!

Posted: 27-12-09 15:08 by Tania


Posted: 27-12-09 15:08 by Tania

erm i was wonderig if anyone can tell me if reduction is gaining an atom


oxidation is gaining a atom, because in some places it says the completly the total tooposite and i am confused!!!! :(

Posted: 28-12-09 19:01 by Tania

oxidation is lose of electrons

reduction is gain

too remember:


oxidation is loss, reduction is gain

:D i use this all the time

you dont gain or lose atoms, you gain or lose electrons

you can look at my reviion cards of electrolysis and it is under there:

http://getrevising.co.uk/resources/c2_electrolysis#s=3 on card 3

Posted: 28-12-09 19:15 by I P B


Posted: 28-12-09 20:06 by Tania

thats ok :D

Posted: 28-12-09 21:14 by I P B