Chemistry: Post your doubts here!

[Metanoia]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w13_qp_11.pdf A
Number 26 Answer is B but why not 4??

w13qp11

4 atoms of H are removed (from 3 COOH and 1 OH).

4H --> 2H2 ( 2 moles of H2 gases)

 

[Browny]

Q5. The molecule is not symmetrical, you have to view it in its 3D shape, it is tetrahedral.

Q6. MgCl2 dissolves, SiCl4 hydrolyses.

Q23. Each carbon has 4 single bonds, they are tetrahedral shape around each carbon.

Q36. NH3 accepts a H+ to form NH4+, it is a proton acceptor (base)

Q39.
H2SO4 (acid) donates a proton to C2H5OH.

Q23, The carbons are in a row like -C-C-C which is 180 right.

I know the bonds are tetrahedral but the C row has a 180 angle right?

 

[Manal.A]

Can anyone pls explain quality mj paper 11 year 2012....how do we find the equilibrium equation

 

[Metanoia]

Q23, The carbons are in a row like -C-C-C which is 180 right.

I know the bonds are tetrahedral but the C row has a 180 angle right?

hmm..this is a bit contradicting, how can it both be tetrahedral and have 180 at the same time?

Carbons in a row doesn't mean 180 degrees..

 

[Gehad Mohamed]

Hi can someone please explain these questions
they are from 9701/11/O/N/12

 

[Browny]

hmm..this is a bit contradicting, how can it both be tetrahedral and have 180 at the same time?

Carbons in a row doesn't mean 180 degrees..

View attachment 44448

OK thanks got it and will you be able to cover at least another 5 years in the coming 5 days in the youtube videos?

 

[$$AK$$]

Guys any tips for solving chemistry p1 ????

 

[FarahMJ]

Help with this one plz, ans is B

 

[Metanoia]

OK thanks got it and will you be able to cover at least another 5 years in the coming 5 days in the youtube videos?

Some years have 3 mcqs, so it depends on the years. I'm working on the 2013 June papers first, then the 2013 Nov papers.

2013 June Paper 12 should be ready (if no uploading issues) by this evening.

 

[kingo44]

Help with this one plz, ans is B

Step 1: Count the hydrogen atoms in the side-chains.
Upper side-chain and lower side-chain: 2 x (3+6+6+14) = 58
Middle side-chain: 3 + 6 + 6 + 14 = 29

Step 2: Count the hydrogen atoms in each residue
First residue: 3 + 8 + 6 + 14 = 31
Second residue x 2 (because two side-chains are converted): 2 x (3 + 14 + 2 + 14) = 66

Step 3: Calculate how many hydrogen atoms had to be added to each side-chain in order to form the residues.
Upper and lower side-chain residues have 66 - 58 extra hydrogens = 8 extra hydrogens
Middle side-chain residue has 31-29 extra hydrogens = 2 extra hydrogens

Step 4: You know that 10 hydrogen atoms have been added to the original molecule. Each hydrogen molecule contains two hydrogen atoms, so there are 10/2 = 5 hydrogen molecules ie. 5 moles of hydrogen

 

[kingo44]

if u need any hel p girl then ask me lol nice pic btw

 

[happyperson]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w12_qp_34.pdf
Can someone please explain me Q1 part c i, how to calculate the initial concentration. Thanks.

 

[Browny]

Some years have 3 mcqs, so it depends on the years. I'm working on the 2013 June papers first, then the 2013 Nov papers.

2013 June Paper 12 should be ready (if no uploading issues) by this evening.

OK thanks so much!

 

[kingo44]

reallty metanoia awesome moreeeeeeeeee videod

 

[kingo44]

reallty metanoia awesome moreeeeeeeeee videod

 

[Metanoia]

Help with this one plz, ans is B

You can check out post #9267 on page 464

 

[Metanoia]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_qp_34.pdf
Can someone please explain me Q1 part c i, how to calculate the initial concentration. Thanks.

Expt 1: moles of H2O2 = original conc x original vol = 0.23 x 0.05 =0.0115 mol
conc of H2O2 at start of experiment 1 = moles of H2O2/volume of solution = 0.0115/0.130 = 0.0885 mol dm-3

 

[sweet.sugar]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w06_qp_1.pdf
Plz help me with 3 questions from o/n/6
Q9-C
Q11-B
Q25-B
Thanku

 

[Metanoia]

Video for June 2013 Paper1_2 is uploaded

http://www.youtube.com/playlist?list=PL4Jmce8VJnNWSchiyYdNNlLsHJlIvfZ35

 

[kingo44]

FINALLYH UPLOAD MORE NOWWWWWWWWWWW