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ocr a f325 revision thread

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can anyone answer my post, whomever answers that question are really prepared for this exam!!
Original post by otrivine
Some of the soluble salt silver nitrate, AgNO3, which is completely dissociated
into silver ions, Ag+
(aq) and nitrate ions, NO3
-
(aq), is added to a saturated solution
of silver hydroxide in equilibrium with solid silver hydroxide:
AgOH(s) ⇌ Ag+(aq) + OH-(aq)
Choose from the options below which one observation you would expect to
make:
A The pH of the solution will increase
B The pH of the solution will decrease
C The equilibrium constant for the reaction above will increase
D The equilibrium constant for the reaction above will decrease
E Some silver hydroxide will dissolve



anyone, is the answer A /

I think its B
Original post by chignesh10
I think its B


why?
Reply 1623
Avatar for LRJ
LRJ
Original post by otrivine
Some of the soluble salt silver nitrate, AgNO3, which is completely dissociated
into silver ions, Ag+
(aq) and nitrate ions, NO3
-
(aq), is added to a saturated solution
of silver hydroxide in equilibrium with solid silver hydroxide:
AgOH(s) ⇌ Ag+(aq) + OH-(aq)
Choose from the options below which one observation you would expect to
make:
A The pH of the solution will increase
B The pH of the solution will decrease
C The equilibrium constant for the reaction above will increase
D The equilibrium constant for the reaction above will decrease
E Some silver hydroxide will dissolve



anyone, is the answer A /


Is there a mark scheme or anything? :s my initial thought is that it would be a Kc change because there is an increase in Ag ions, so the equilibrium would shift to the left? for the reaction AgOH(s) ⇌ Ag+(aq) + OH-(aq) ?

Although with OH- ions in there it could be a pH change :s

EDIT: so D?
(edited 10 years ago)
Original post by otrivine
why?


increase in concentration of Ag+ ions shifts the equilibrium to the left, there is a decrease in the concentration of OH- ions, and therefore ph decreases
Original post by chignesh10
increase in concentration of Ag+ ions shifts the equilibrium to the left, there is a decrease in the concentration of OH- ions, and therefore ph decreases


That is correct, well done, but then NO3- is releasing , does that not affect anything?
Original post by otrivine
That is correct, well done, but then NO3- is releasing , does that not affect anything?


nope NO3- doesnt affect anything
Reply 1627
Avatar for Lehal
Lehal
Hey, I'm just going through the papers.. on june 10.. can something just explain why there are 8 electrons in the second equation please..
Reply 1628
Avatar for Funtry
Funtry
15
Burning out!
Original post by Funtry
Burning out!


How much are you doing!??! O.o
Reply 1630
Avatar for Funtry
Funtry
15
Original post by chignesh10
How much are you doing!??! O.o


Just read over Ligands and complex ions tonight, for about 40 minutes, doing 50 minutes reading on Eqm tonight, I just want exams in general to be over though!
Original post by otrivine
can anyone answer my post, whomever answers that question are really prepared for this exam!!


It is D. AgOH⇌Ag(+) + OH(-)
If Ag(+) is added it reacts with OH(-) thus decreasing the Kc value.
pH may also decrease, but I am not sure because there will be less OH(-) ions.
(edited 10 years ago)
Reply 1632
Avatar for Better
Better
8
Original post by Funtry
Just read over Ligands and complex ions tonight, for about 40 minutes, doing 50 minutes reading on Eqm tonight, I just want exams in general to be over though!


Kind of looking forward to the exams tbh. I actually enjoy working right now; love when you weren't able to do something before, you go back and read a bit then boom!!

School is great - it's all linear progression.

Exam I'm looking forward to most is Chem 4, and C4; as they are the ones that pose the biggest challenge right now.

Can't imagine what else I would be doing except studying; when Exams are over I'm probably going to be reading more Out of School books than I am right now, so it's all pretty much the same routine.
Original post by Funtry
Just read over Ligands and complex ions tonight, for about 40 minutes, doing 50 minutes reading on Eqm tonight, I just want exams in general to be over though!

Ah OK, yeah i guess so! What are you planning to do for f325 tomorrow?
What challenging questions could actually be asked on transition metals/elements as I'm struggling to see where they become challenging :redface: Same with all the calculation questions too.
Original post by Funtry
Just read over Ligands and complex ions tonight, for about 40 minutes, doing 50 minutes reading on Eqm tonight, I just want exams in general to be over though!


do you find dipole dipole interaction in all molecules?
Original post by MathsNerd1
What challenging questions could actually be asked on transition metals/elements as I'm struggling to see where they become challenging :redface: Same with all the calculation questions too.


Transition elements are all recall so they are pretty easy. Look at the F325 Spec paper, last question is worth 20 marks so pretty challenging.
Original post by DudeBoy
Transition elements are all recall so they are pretty easy. Look at the F325 Spec paper, last question is worth 20 marks so pretty challenging.


That's very true and I've done it and got 20/20, it's not that hard just time consuming really and all the calculation questions can be done if you think logically about it :smile:
Original post by MathsNerd1
That's very true and I've done it and got 20/20, it's not that hard just time consuming really and all the calculation questions can be done if you think logically about it :smile:


Yeah I am feeling pretty confident for f325 tbh need 118 ums for an A and I am resitting F324, just praying that I don't make so many stupid mistakes like I did in the mock :smile:
Reply 1639
Avatar for ShogDX
ShogDX
5
I was just wondering, what are all of the colours of the transition metal/ligand complexes that we need to know? Thanks :smile:

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