[kingam]

(Original post by otrivine)
No you would do a precepitation reaction
but yes you seem to get the point
ok my turn

What's the kw value

[otrivine]

(Original post by kingam)
What's the kw value

we are given that in the exam its the ionic produvt of water Kw=(h+)(oh-)

[kingam]

(Original post by otrivine)
we are given that in the exam its the ionic produvt of water Kw=(h+)(oh-)

Yh it's 1 times 10 to the power of minus 14

[otrivine]

(Original post by kingam)
Yh it's 1 times 10 to the power of minus 14

thanks
Define:bronsted browry acid

[Silkyy]

(Original post by Killjoy-)
All quantities must have the same prefix, so either all in kilo or all without kilo.

Thank you!

[kingam]

(Original post by otrivine)
thanks
Define:bronsted browry acid

Proton donor , and it's Lowry I think that's how you spell it x

[otrivine]

(Original post by kingam)
Proton donor , and it's Lowry I think that's how you spell it x

lol thanks i find the spelling hard
my turn

[kingam]

(Original post by otrivine)
lol thanks i find the spelling hard
my turn

what a mono basic acid

[otrivine]

(Original post by kingam)
what a mono basic acid

WHAT DO U MEAN BY MONO?sorry

[kingam]

(Original post by otrivine)
WHAT DO U MEAN BY MONO?sorry

Its an acid containing only one replaceable hydrogen atom per molecule for eg HCL OR HNO3

[atman7]

Anyone got links to the Jan 2012 paper and mark scheme, used to have it but can't find it and it got deleted on the Jan past paper thread here

[Killjoy-]

(Original post by atman7)
Anyone got links to the Jan 2012 paper and mark scheme, used to have it but can't find it and it got deleted on the Jan past paper thread here

It's here: http://www.thestudentroom.co.uk/show...2#post37542315
MS is further down the page.

Thank Cath-ay and maddy93x.

[karo16]

Does anyone know whether we have to know the details of the hydrogen oxygen fuel cells? Are we expected to remember the equations that take place at each electrode?

In the spec it says (j) explain that a fuel cell uses the energy from
the reaction of a fuel with oxygen to create a
voltage;

[pcorbett94]

(Original post by karo16)
Does anyone know whether we have to know the details of the hydrogen oxygen fuel cells? Are we expected to remember the equations that take place at each electrode?

In the spec it says (j) explain that a fuel cell uses the energy from
the reaction of a fuel with oxygen to create a
voltage;

We are not "expected" to know the equations as far as the syllabus is concerned, but we are instead meant to be able to construct them when they give us pointers. My teacher told us to just remember the oxygen reduction half equation in both acidic and alkaline conditions, and then by using the overall "combustion" equation, deduce the other half equation.

Hope that made any sort of sense.

[S_Azizi]

Do we have to know how to distinguish between square planar complexes and tetrahedral complexes?

[mathsclown]

First module done = mainly calculations I guess
Starting the rates module should have that and the half cell stuff done today, then finish off transition metals and the thermodynamics part by friday, then one week to do past papers!!

[silver0]

(Original post by mathsclown)
First module done = mainly calculations I guess
Starting the rates module should have that and the half cell stuff done today, then finish off transition metals and the thermodynamics part by friday, then one week to do past papers!!

I'm basically doing similar revision to you, and I hope to finish this week then concentrate on past papers next week damn this unit is hard...

[rasklatz]

For the thiosulfate/iodine and hydrogen peroxide titrations are we meant to memorise any equations?

[chemicalX]

(Original post by Killjoy-)
It's here: http://www.thestudentroom.co.uk/show...2#post37542315
MS is further down the page.

Thank Cath-ay and maddy93x.

Hi does anybody know how to do ratio buffer questions, similar to the jan 12 mock we did? those questions are so confusing, anybody know how to tackle such questions?

[Killjoy-]

(Original post by chemicalX)
Hi does anybody know how to do ratio buffer questions, similar to the jan 12 mock we did? those questions are so confusing, anybody know how to tackle such questions?

You may want to use this equation:



It is simply a logarithmic form of the K_a equation you are used to.

Remember and are the concentrations of conjugate base and undissociated acid at equilibrium.
So represents the log to base 10 of conjugate base: acid ratio.

You need to find at equilibrium but in order to do this you need to find the value for the carbonic acid first.

1. The clue is to notice that you have been given the ratio at a particular pH, so this will enable you to find and use it to answer the question.

2. Once you have found pKa you sub it into the equation with the pH of blood the patient has and solve for the ratio.

I can't really type out all the working but I'll attach a picture:

Alternatively you may use the other form of the Ka equation, but that will involve more anti-logging I think.