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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: slothpomba on November 10, 2010, 09:35:49 pm

Title: kingpomba's last minute chem bonanza
Post by: slothpomba on November 10, 2010, 09:35:49 pm
Hey guys just some questions from exams i've been rushing today, thanks for all the help in advance.

I selected C... i dont see
Edit:Stupid question... moving along

Why is the answer C... is it because of dilution?
(http://img837.imageshack.us/img837/5452/chem2.png)
Title: Re: kingpomba's last minute chem bonanza
Post by: fady_22 on November 10, 2010, 09:39:22 pm
H+ reacts with OH-, removing it from the equilibrium system. Although there is a net forward reaction to oppose it, it is only partial and hence overall the concentration of OH- would decrease.
Title: Re: kingpomba's last minute chem bonanza
Post by: slothpomba on November 10, 2010, 09:41:44 pm
Ah thanks, i see now.

Anyone care to provide an example of any kind using the Ka values... the part of this unit i hate the most -_-
Title: Re: kingpomba's last minute chem bonanza
Post by: Martoman on November 10, 2010, 09:52:29 pm
heres a question for ya

What acid in the data book would give you the highest pH?
Title: Re: kingpomba's last minute chem bonanza
Post by: Stroodle on November 10, 2010, 09:54:20 pm
heres a question for ya

What acid in the data book would give you the highest pH?

Thymol blue? :)
Title: Re: kingpomba's last minute chem bonanza
Post by: Martoman on November 10, 2010, 09:55:59 pm
See thats the point of this question, and it is very probable for tommorrow in terms of VCAA tricks. I asked for the HIGHEST pH.
Title: Re: kingpomba's last minute chem bonanza
Post by: jasoN- on November 10, 2010, 09:57:29 pm
is it hydrocyanic acid?
Title: Re: kingpomba's last minute chem bonanza
Post by: Stroodle on November 10, 2010, 09:57:37 pm
Lol, i know. My humour is not the greatest..

It's Arachidonic acid.












or Phenolphthalein.
Title: Re: kingpomba's last minute chem bonanza
Post by: mostafa1002 on November 10, 2010, 09:58:17 pm
you sly dog you ;)
Title: Re: kingpomba's last minute chem bonanza
Post by: Linkage1992 on November 10, 2010, 09:58:21 pm
is it ammonium ion acid?
Title: Re: kingpomba's last minute chem bonanza
Post by: mostafa1002 on November 10, 2010, 09:59:37 pm
i cbf getting my data book, its whatever acid has the LOWEST Ka value.
Title: Re: kingpomba's last minute chem bonanza
Post by: toshibaj on November 10, 2010, 09:59:53 pm
Hey sorry to hijack, but could someone explain to me VCAA 2008 Question 8b? It's the question about the flow of the electrolyte in a fuel cell.
Title: Re: kingpomba's last minute chem bonanza
Post by: Martoman on November 10, 2010, 10:00:02 pm
Lol, i know. My humour is not the greatest..

It's Arachidonic acid.












or Phenolphthalein.

we have a winner
Title: Re: kingpomba's last minute chem bonanza
Post by: jasoN- on November 10, 2010, 10:00:11 pm
Lol, i know. My humour is not the greatest..

It's Arachidonic acid.
well played.
Title: Re: kingpomba's last minute chem bonanza
Post by: Martoman on November 10, 2010, 10:00:55 pm
Hey sorry to hijack, but could someone explain to me VCAA 2008 Question 8b? It's the question about the flow of the electrolyte in a fuel cell.

anions move to anode
Title: Re: kingpomba's last minute chem bonanza
Post by: Linkage1992 on November 10, 2010, 10:01:04 pm
oops i didn't even look at the indicators!
Title: Re: kingpomba's last minute chem bonanza
Post by: Martoman on November 10, 2010, 10:01:46 pm
if this is a question tomorrow this will be massive win
Title: Re: kingpomba's last minute chem bonanza
Post by: Stroodle on November 10, 2010, 10:03:16 pm
Maybe this is the error question they were talking about. They forgot about the indicators in their answers!
Title: Re: kingpomba's last minute chem bonanza
Post by: toshibaj on November 10, 2010, 10:03:28 pm

anions move to anode

I thought that only occurs in galvanic cells, when charge becomes unbalanced?
Title: Re: kingpomba's last minute chem bonanza
Post by: Martoman on November 10, 2010, 10:04:41 pm
in any case this is true.

Title: Re: kingpomba's last minute chem bonanza
Post by: toshibaj on November 10, 2010, 10:08:46 pm
in any case this is true.

I'll take your word for it for fuel cells, but certainly not for any case.

I remember doing an exam question about an electrolytic cell. They explained that the nitrate ion migrated towards positive electrode.  

EDIT: just realised that is the anode. stupid me!
Title: Re: kingpomba's last minute chem bonanza
Post by: Martoman on November 10, 2010, 10:11:03 pm
:)

Anions to ANode

Cations to Cathode.

Works every time.
Title: Re: kingpomba's last minute chem bonanza
Post by: Slumdawg on November 10, 2010, 10:13:43 pm
so why isn't it hydrocyanic acid? :S
Title: Re: kingpomba's last minute chem bonanza
Post by: Martoman on November 10, 2010, 10:18:01 pm
5*10^-10 < 6.3*10^-10 dearie
Title: Re: kingpomba's last minute chem bonanza
Post by: Slumdawg on November 10, 2010, 10:20:32 pm
5*10^-10 < 6.3*10^-10 dearie
ohhhh hahaha. I kept scanning for the highest power. Then when I got to 10, I just stuck with the highest number and was convinced it was 6.3 haha. Thanks :)
Title: Re: kingpomba's last minute chem bonanza
Post by: Martoman on November 10, 2010, 10:21:05 pm
thats another reason why this question is sexy for VCAA
Title: Re: kingpomba's last minute chem bonanza
Post by: Slumdawg on November 10, 2010, 10:21:41 pm
thats another reason why this question is sexy for VCAA
Very true. Very Vcaa-esque. Nice one martoman!
Title: Re: kingpomba's last minute chem bonanza
Post by: Martoman on November 10, 2010, 10:30:07 pm
another random one related to K

How can the EMF give an indication about K?