Chemistry Unit 4 ~ Help questions.

[donkey]

Hi.
Can I have some help with these?
Thank you.

Mod Edit: Thread title changed to make the thread clearer.

- Gloamglozer

Mod Edit: Thread title changed to the correct subject.

- Mao

Donkey Edit: Thread title changed to further correct the subject

[Whatlol]

For the reaction = (this is because the first reaction had enthalpy  will be

the reverse reaction is

But since they have doubled the coifficents, the enthalpy will be doubled.

[donkey]

Thank you Whatlol. Any idea about the half cell one?

[Whatlol]

Thank you Whatlol. Any idea about the half cell one?

I would help but i havent covered the theory for it, and i have limited knowledge of it from last year so i dont want to confuse you. sorry.

[vexx]

^ In Galvanic cells, where oxidation is the Anode and occurs at the negative terminal, and where reduction is at the Cathode at the positive terminal. Each reaction is separate as there are four done, so for each of the reactions, you can see that the positive electrode (being the cathode in galvanic cells only) will be where the strongest oxidant is, and the anode will have the strongest reductant.
Like for I and IV reacting, P(+) is the stronger oxidant and Cu(-) is the stronger reductant.
Just use that info. to make a list of what beats what and you'll get the right answer.

the edited title is wrong btw, this is galvanic cells, not electrolytic.

[donkey]

Thank you Vexx.

At what stages of the contact procress is the H2SO4 a liquid, and when is it aqeous?

[donkey]

Also, in the 2008 CHEM exam 2 short answer section: the value in JKmol-1 of deltaH for the reaction written is asked for. Where is this knowledge supposed to come from? Is this part of a number of deltaH values we should memorise from the book? Upon looking at my book to see for this information I found data that was slighty off the examiners solution so I don't know where this answer should have come from since I can't see how it comes from the data.

[andy456]

Without seeing the exam, Theres a section in the hienmann textook on thermochemical equations and im pretty sure it shows how to find deltaH