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Wjec ch5 22 june 2016 thread

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Reply 20

littleover13

you forgot to square it dumbass xD

Reply 21

SackSly

I wasn't sure about why the salt was slightly alkaline at the temperature either... I worked out that the pH of water at that temperature was around 6, so I just said that the salt is slightly alkaline to cancel the acidity of the water out? I have no clue :')

Reply 22

studygirl300

What did people get ffor the. Question on why a salt dissolved in water had a ph higher then 7 and kw of water

Reply 23

Sznsnsn

Original post by studygirl300

What did people get ffor the. Question on why a salt dissolved in water had a ph higher then 7 and kw of water

I said that the salt anion absorbs H+ and it's only slightly alkaline because kw was low so not many H+ in solution to be absorbed

Reply 24

studygirl300

Ok thanks thats what i said

Reply 25

Pixie1234

What indicator did you put?

Reply 26

SackSly

Original post by Pixie1234

What indicator did you put?

I think the indicator was Starch due to the Iodine?

Reply 27

matthewdjones

Anyone think the two 6 markers were overly mean. they never ask about precipitate reactions of complexes and they just shove a QWC in on it where u have to remember the observations and the formula! Same for the QWC in Q5, were we really supposed to remember all those reactions?!

Reply 28

Hedd11

Do you think the marking boundaries will be higher or lower than last year?

Reply 29

Pixie1234

Original post by SackSly

I think the indicator was Starch due to the Iodine?

I put that too! What about when you had to choose which indicator to use for the titration curve??

Reply 30

Sznsnsn

Original post by matthewdjones

It wasn't complex precipitates it was just copper ions with OH ions for the precipitate

Reply 31

Pixie1234

Anyone remember what the got Gibbs free energy question?

(edited 7 years ago)

Reply 32

Sznsnsn

Original post by ALevel Student 1

I calculated the H+ and OH- concentrations and found that the OH- conc was higher than H+ so it was alkaline
Answers I got, cant remember what for:
think maybe for rate mol-1dm3s-1
0.083 NaOH conc
530 for entropy change
0.78 for something, cant remember what
59.5% copper
W and Y were the acids used because of inital ph. The indicator was the one with 8.0-9.6 range
7.29 x 10^-5 atm-2 for the kp I think
-891 for the Born Haber one
Let me know what you guys think.
I thought it was a straightforward paper and expect boundaries not to fluctuate much from last year.

I got these, the one I was most worried about was the kp one but I got that :smile:

Reply 33

Formless

Original post by Pixie1234

Anyone remember what the got Gibbs free energy question?

-20ish

Reply 34

Formless

Original post by SackSly

I think the indicator was Starch due to the Iodine?

Put Starch too :smile:

) Hope its right

Reply 35

Formless

H+ Had order 1, I- had order 0. So what was the rate equation?

Reply 36

ishanS

Original post by marethyu

-20 kJ ish

Yeah I'm almost certain its starch

k(h+)(CH3COOCH3)

-20 kJmol^-1K^-1 ish

Reply 37

Formless

Original post by marethyu

-20 kJ ish

Yeah I'm almost certain its starch

k(h+)(CH3COOCH3)

perfect thanks

Reply 38

wwwwwwwwwwwf

I got -860kJmol -1 for the born haber cycle for formation of BaCl2 and go -22.94 for the gibbs free energy change

Also got 59.5% copper content in the brass and 0.083 for NaOH concentration

Got 4.9x10-5 somewhere too I think, aswell as 7.0x105?