[Smiley Face :)]

(Original post by Oromis263)
Sure, I'm up for it, I should probably make sure I remember this module.

Just added some q's

[otrivine]

(Original post by Oromis263)
Sure, I'm up for it, I should probably make sure I remember this module.

ok you start

[otrivine]

(Original post by Smiley Face :))
What colour is [Cu(NH3)4(h20)6] ?
What is the definition of a transition metal?
Name a multidente ligand?
What is an optical isomer?
What colour is the [Fe(OH)3] preciptitate?
Tell me what pKa is?
Why do we need a salt bridge?
Explain the use of tranistion metal ions if haemoglobin?
What doe cis platin do?

1) deep blue ppt
2) transition metal is a metal with a partially filled d sub shell
3) do you mean bidendate 2? or not if so its dicarboxylate and en
4) is an isomer where it is non superimposable images of each other
5) rust brown ppt
6)PKA is -log(ka)
7)for ions to move from one solution to another
8)binds with fe2+ oxygen to carry oxygen around the body
9) to prevent cancer

[Oromis263]

(Original post by Smiley Face :))
What colour is [Cu(NH3)4(h20)6] ?Deep blue solution

What is the definition of a transition metal?
A transition metal is an element which can form an ion with an incomplete d-subshell

Name a multidente ligand?
Edta?

What is an optical isomer?
Optical isomers are non-super imposable mirror images of each other. (They rotate plan polarised light in opposite directions)

What colour is the [Fe(OH)3] preciptitate?
It is a rusty brown gelatinous precipitate

Tell me what pKa is?
pKa = -logKa

Why do we need a salt bridge?
For the transfer of ions, whilst not taking part in the cell reactions

Explain the use of tranistion metal ions if haemoglobin?
The haem group in haemoglobin is an Fe ion surrounded by ligands. Oxygen can form a coordinate bond with the Fe ion whilst in the lungs, from where the blood transports the oxygen to the body, exchanging the oxygen with carbon dioxide at the cells. (Carbon dioxide has a larger Kstab)

What doe cis platin do?
cis-platin is a cancer fighting drug. It binds with the DNA in cancerous cells, preventing division.

Answers in quote

[Oromis263]

My turn!

1. Write the electron configuration of Copper
2. State 3 properties of transition elements
3. Define co-ordinate bond
4. State the bond angle of an octahedral complex
5. Define a bronsted-lowry base
6. Why would you not use sulfuric acid or nitric acid when giving an example of acid reactions with metals?
7. Define pH
8. Define buffer solution
9. State the conditions required for an equilibrium.
10. Define Lattice Enthalpy
11. Which half-cell is the most positive (positive terminal)? (left or right)

[otrivine]

(Original post by Oromis263)
My turn!

1. Write the electron configuration of Copper
2. State 3 properties of transition elements
3. Define co-ordinate bond
4. State the bond angle of an octahedral complex
5. Define a bronsted-lowry base
6. Why would you not use sulfuric acid or nitric acid when giving an example of acid reactions with metals?
7. Define pH
8. Define buffer solution
9. State the conditions required for an equilibrium.
10. Define Lattice Enthalpy
11. Which half-cell is the most positive (positive terminal)? (left or right)

1) 1s2,2s2,2p6,3s2,3p6,4s1,3d10
2)variable oxidation state,coloured compounds, catalysts
3)total number of coordinate bond that is formed beween a transition metal ion and ligands
4)90
5)proton acceptor
6)because it is not part of reaction in ligand substitution has to be with conc hcl ? is it because they fully dissociate ?
7)-log(h+)
8)is adding small amount of acid and base to minimise PH change
9)the rate of forward reaction is same as backwards reaction , concentration , temp,pressure
10)it is the enthalpy change when 1 mole of ionic compound is formed from its gaseous ions under standard conditions
11)is it right?

[Oromis263]

(Original post by otrivine)
1) 1s2,2s2,2p6,3s2,3p6,4s1,3d10
Correct

2)variable oxidation state,coloured compounds, catalysts
Correct

3)total number of coordinate bond that is formed beween a transition metal ion and ligands
I think you misread this one

4)90
Correct

5)proton acceptor
Correct

6)because it is not part of reaction in ligand substitution has to be with conc hcl ? is it because they fully dissociate ?
This one is just something my teacher told me to remember. They are actually powerful oxidising agents, and so may affect the reaction.

7)-log(h+)
Correct

8)is adding small amount of acid and base to minimise PH change
Your wording is a bit muddled. I would stick with: A buffer solution is a solution which will act to minimise the changes in pH upon the addition of small amounts of acid or base.

9)the rate of forward reaction is same as backwards reaction , concentration , temp,pressure
Correct, remember the container must be sealed, and that the equilibrium can be approached from either direction.

10)it is the enthalpy change when 1 mole of ionic compound is formed from its gaseous ions under standard conditions
Correct

11)is it right?
Correct

Corrections in quote.

[VQG]

(Original post by walkbesideme)
I'm sure we don't; can you remember which paper this was?

January 2011 I believe.

Another thing I'm struggling with at the moment is working out how many electrons you need to balance an equation i.e. Jan 10 q. 6b

Balance:

Cr2O72- + H+ +e- ---> Cr2+ +H20

I balanced out the oxygens first and the Cr's. I then balanced the H+, but how do I know how many electrons I need :s

[Oromis263]

(Original post by VQG)
January 2011 I believe.

Another thing I'm struggling with at the moment is working out how many electrons you need to balance an equation i.e. Jan 10 q. 6b

Balance:

Cr2O72- + H+ +e- ---> Cr2+ +H20

I balanced out the oxygens first and the Cr's. I then balanced the H+, but how do I know how many electrons I need :s

Charge must always be conserved in a chemical reaction, thus you have to balance the charges too. So, use enough electrons to balance the charge and you're fine.

EDIT: The answer to the question you asked is:

[kemekpo]

Can someone help me with the Jan 10 paper 7b).

Where you have to find the conc of the origingal h202, the mark scheme says the calculation to do this is 1.1725x10(-2) multiplied by 34 multiplied by 40.
Where has this figure of 40 come from?
How do you find the conc of the undiluted hydrogen of peroxide give that I've worked out the moles of H202 in 250 to be 0.011725.

Thanks in Advance

[VQG]

(Original post by Oromis263)
Charge must always be conserved in a chemical reaction, thus you have to balance the charges too. So, use enough electrons to balance the charge and you're fine.

EDIT: The answer to the question you asked is:

So by that do you mean the charge on the Cr?
Just to confirm: Cr2 is +12 on the LHS. On the RHS it's +4.. hence 8 electrons to balance it? Am I right?

[Oromis263]

(Original post by VQG)
So by that do you mean the charge on the Cr?
Just to confirm: Cr2 is +12 on the LHS. On the RHS it's +4.. hence 8 electrons to balance it? Am I right?

Cr2 isn't +12, just the left-hand side overall is +12. Other than that, yes you're right about why you need 8 electrons, to balance the difference.

[VQG]

(Original post by Oromis263)
Cr2 isn't +12, just the left-hand side overall is +12. Other than that, yes you're right about why you need 8 electrons, to balance the difference.

Ah okay thanks.

Another question:
January 2010 7b)

Once you work out the moles of H202 in 250cm3.
You multiply it by the mr of H202 to work out the mass of H202 in grams. But why do they multiply it by 40? Shouldn't it be by 4? Because 1dm3 is 4 x 250cm3?

[Oromis263]

(Original post by VQG)
Ah okay thanks.

Another question:
January 2010 7b)

Once you work out the moles of H202 in 250cm3.
You multiply it by the mr of H202 to work out the mass of H202 in grams. But why do they multiply it by 40? Shouldn't it be by 4? Because 1dm3 is 4 x 250cm3?

By working backwards, you use the equation in part a to find the moles of H2O2 in the titration, then multiply by 10 to get how much is in the 250.0cm^3, However! The first sentence says that this is diluted, so you then multiply by 40 to find the concentration of the original undiluted hydrogen peroxide.

[VQG]

(Original post by Oromis263)
By working backwards, you use the equation in part a to find the moles of H2O2 in the titration, then multiply by 10 to get how much is in the 250.0cm^3, However! The first sentence says that this is diluted, so you then multiply by 40 to find the concentration of the original undiluted hydrogen peroxide.

Got it! Life saver if there ever was one! Slightly more confident on my titration calculations now - which is my weakness

[je t'aime]

Hi everyone!

Seriously stressing about how near this exam is now and I haven't even thought about the big biology unit which is going to be awful.

I did the jan 2011 paper today and it's completely knocked my confidence - i know it was a hard paper but I've literally done everything and am pretty gutted I couldn't do more of it

Was just wondering whether anyone can recommend any good resources online to improve exam technique/especially constructing half equations and calculations? I'm trawling through the old papers from 2002 onwards but there's not a lot in there so was just wondering if anyone had found much else?

Good luck to everyone! (:

[chemicalX]

(Original post by je t'aime)
Hi everyone!

Seriously stressing about how near this exam is now and I haven't even thought about the big biology unit which is going to be awful.

I did the jan 2011 paper today and it's completely knocked my confidence - i know it was a hard paper but I've literally done everything and am pretty gutted I couldn't do more of it

Was just wondering whether anyone can recommend any good resources online to improve exam technique/especially constructing half equations and calculations? I'm trawling through the old papers from 2002 onwards but there's not a lot in there so was just wondering if anyone had found much else?

Good luck to everyone! (:

What did you get on it?

[otrivine]

(Original post by chemicalX)
What did you get on it?

hi mate how are you shall we start revisio mate what did u get for chem jan 2011 paper?

[je t'aime]

(Original post by chemicalX)
What did you get on it?

64. I know it was not far off an A but there were no silly mistakes I honestly couldn't do the rest of it! I also need an A cos I hold an aaa offer though I was aiming for an A* as my insurance is a*ab :/

Just wondering what people had found useful

[chemicalX]

(Original post by otrivine)
hi mate how are you shall we start revisio mate what did u get for chem jan 2011 paper?

I skipped it LOL i did bio jan 11 instead im doing the jan 11 of chem in half an hour!

what did you get for chem jan 11?