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# Equilibria, Energetics and Elements (F325) - June 2011 Exam. watch

1. (Original post by SteveScott)
Does pKa = pH?
nooooooooooooooo

pka= -logka

ka= 10^-pka
2. (Original post by ViralRiver)
Do we need to remember colours and oxidation states? What about redox equilibria such as MnO4 and Fe etc?
^^
3. (Original post by SteveScott)
Does pKa = pH?
pKa is basically just -log(Ka), its not pH.
the actual Ka calculation can be used to work out the pH if you work out the concentration of H+
4. (Original post by Flint_09)
nooooooooooooooo

pka= -logka

ka= 10^-pka

hmmmmmm.....Are you sure?

Jokes
5. (Original post by asem93)
NO! NO! NO!
Haha

I know pKa = -logKa , so 10^-pKa = Ka

Ka = [H+][A-]/[HA]

but i thought i saw something about pka being equal to pH for weak acids.....I dunno.
6. (Original post by ViralRiver)
^^
Colours of common compounds
7. Good Luck Everyone!!

Lets just hope its an easy paper
8. what are the cycles called that involve lattice enthalpy and enthalpy change of solution and do we have to know them??
9. Do we need to know tetrahedral complex metal ions??
10. (Original post by Perky perks)
what are the cycles called that involve lattice enthalpy and enthalpy change of solution and do we have to know them??
Yes

Born Haber cycles

It all depends on the reaction. If it gives a table, look at the enthalpy change values.
11. (Original post by Perky perks)
what are the cycles called that involve lattice enthalpy and enthalpy change of solution and do we have to know them??
They are a form of Born Haber cycle, you can also argue a bit like Hess' Law
12. (Original post by 123trident)
actually, I'm a bit confused on free enrgy feasiblity. Can someone go throug all the options explaining them, please?
a reaction is feasiable only if the free gibs energy G is less than zero (so negative value).
This can only happen if the enthalpy H is negative and the entropy S is positive
or when enthalpy is positive and entropy positive (reaction will take place at low temperatuures only) or when enthalpy is negative and entropy is also negative.

these combinations all should lead to G being less than zero and hence reactions are feasiable

LOL was that confusing? sorry

they all follow equation G=H - ST
13. does the ionic radius decrease as you move from left to right of periodic table?
14. Just done Jan 2011, got 72/100 which was a comfortable A it seems.

Does anyone know what the raw mark was for 100% UMS for Jan 2011, out of interest?
15. (Original post by susan23)
a reaction is feasiable only if the free gibs energy G is less than zero (so negative value).
This can only happen if the enthalpy H is negative and the entropy S is positive
or when enthalpy is positive and entropy positive (reaction will take place at low temperatuures only) or when enthalpy is negative and entropy is also negative.

these combinations all should lead to G being less than zero and hence reactions are feasiable

LOL was that confusing? sorry

they all follow equation G=H - ST
When delta G is less than 0 !!
16. (Original post by InsaneFandom)
Do we need to know tetrahedral complex metal ions??
You need to know at least one of octohedral, tetrahedral and the flat one with four ligands, and at least one optical and stereoisomer, but I'd have thought two would be preferable.
17. (Original post by Perky perks)
what are the cycles called that involve lattice enthalpy and enthalpy change of solution and do we have to know them??
they are another type of born-haber cycle, and yep i think we do need to know them.
18. GOOD LUCK PEOPLE.... hopefully we get a good paper....
19. (Original post by hiyarearl)
Just done Jan 2011, got 72/100 which was a comfortable A it seems.

Does anyone know what the raw mark was for 100% UMS for Jan 2011, out of interest?
Is that on the internet?
20. (Original post by hiyarearl)
Just done Jan 2011, got 72/100 which was a comfortable A it seems.

Does anyone know what the raw mark was for 100% UMS for Jan 2011, out of interest?
80

And believe it or not I got 72 as well!

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