Chemistry: Post your doubts here!

[HorsePower]

Is dis d thread being used for chem p1???

this and some others ...

 

[zackle09]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdf

how do you do question 6?
and how is the answer D for question number 30? :/

 

[h4rriet]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdf

how do you do question 6?
and how is the answer D for question number 30? :/

6 is done simply by using pV=nRT.
Compound Z is an ester, so the answer can be either C or D. D shows an ester formed using propanoic acid and C shows an ester formed using hexanoic acid. Compound X has 6 Carbons.

 

[Tanvir Azad]

2-x : x/2 : x

In essence, it's a pretty simple question if you ask me. People tend to get confused seeing variables instead of constants.

Anyhow.

There are two approaches to this.

One is quicker but much more confusing. If you want, let me know and I'll enlist that too.

If not, simply take the equations and manipulate.

A- Inital: 2 : 0 : 0
Final : 2-x: 2x : x
Total moles: 2-2+2x+x = 3x so A is incorrect.

B-
Initial: 2 : 0 : 0
Final: 2-2x : 2x : x
Total moles: 2-2x+2x+x = 2+x so B is incorrect

C-
Initial: 2 : 0 : 0
Final 2-2x:x:x
Total = 2-2x+x+x = 2

D-
Initial: 2 : 0 : 0
Final: 2-x : x/2 : x [x = 2R]
Total moles = 2-x+x/2+x =2+x/2 mols!

Abby, thanks a lot bro...I got it now..

 

[Tanvir Azad]

okay the only way i get D is by substituting X with the no. of moles of R from the equations. Then find total moles. The equation which has same no. of moles is the right 1 and i got D that way

Thank you, i got it..

 

[zackle09]

6 is done simply by using pV=nRT.
Compound Z is an ester, so the answer can be either C or D. D shows an ester formed using propanoic acid and C shows an ester formed using hexanoic acid. Compound X has 6 Carbons.

i used pV=nRT but im getting a weird answer :/
and for 30.... in esters doesn't the alcohol come on the right side tho?

 

[Mairaxo]

i used pV=nRT but im getting a weird answer :/
and for 30.... in esters doesn't the alcohol come on the right side tho?

Q6- find the mass of ice 1st using density=mass/volume. u get mass 1g. find moles of ice. 1/18=0.056
then V=nRT/P = 0.056*8.31*596/101000 = 0.00027m^3 then convert to dm^3

Q30- alcohol comes on the right side. In C also ethanol is at the right. X is oxidised into Y and Y reacts with alcohol meaning Y is an acid. Acid is formed from oxidation of aldehyde. C6H12O is oxidised to C6H12O2. Confirm by counting the atoms of C in the options

 

[Aymen Ezazi]

i have so many doubts in all the papers so i m lining them up, plzz help me.. exam's after a few days..

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s04_qp_1.pdf ques 1, 3 , 9 , 20 , 28

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w04_qp_1.pdf ques 3 , 9 , 10 , 12 , 13 , 22 , 28, 33

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s05_qp_1.pdf ques 7 , 13 , 27 , 31

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w05_qp_1.pdf ques 4 , 15 , 17 , 20 , 24 , 33

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w06_qp_1.pdf ques , 4 , 9 , 11, 14 , 21 , 37 , 39 , 40

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s07_qp_1.pdf ques 2 , 6 , 9 , 26 , 28 , 32 , 40

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w07_qp_1.pdf ques 1 , 5, 9 , 12 , 13, 19 , 30 , 40

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdf ques 2 , 6, 27

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w08_qp_1.pdf ques 2 , 11 , 30 , 39

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s09_qp_1.pdf ques 17 , 19 , 20 , 28 , 29 , 38

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w09_qp_11.pdf ques 2, 20 , 21, 22 , 23 , 28 , 29 , 31 , 37

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_11.pdf ques 1 , 4 , 6 , 8 , 9 , 10 , 18 , 21 , 29 , 30 , 35 , 38

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_11.pdf ques , 9 , 12 , 20 , 26 , 29 , 35 ,

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_qp_11.pdf ques 8 , 11 , 13 , 23

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_11.pdf ques 8 , 9 , 15 , 16 , 20 , 23, 25 , 36 ,

thats a lot of doubts

 

[Mustafa Malik]

Hello everyone
I am new to this part of Xtremepapers cuz i hv just finished my O levels n in these vacations i wanna study for A levels .Although i created a thread but there was no reply. Actually i need the name of the best books for chemistry A levels that most renown skools follow.

 

[Mairaxo]

i have so many doubts in all the papers so i m lining them up, plzz help me.. exam's after a few days..

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s04_qp_1.pdf ques 1, 3 , 9 , 20 , 28

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w04_qp_1.pdf ques 3 , 9 , 10 , 12 , 13 , 22 , 28, 33

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s05_qp_1.pdf ques 7 , 13 , 27 , 31

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w05_qp_1.pdf ques 4 , 15 , 17 , 20 , 24 , 33

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w06_qp_1.pdf ques , 4 , 9 , 11, 14 , 21 , 37 , 39 , 40

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s07_qp_1.pdf ques 2 , 6 , 9 , 26 , 28 , 32 , 40

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w07_qp_1.pdf ques 1 , 5, 9 , 12 , 13, 19 , 30 , 40

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdf ques 2 , 6, 27

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w08_qp_1.pdf ques 2 , 11 , 30 , 39

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s09_qp_1.pdf ques 17 , 19 , 20 , 28 , 29 , 38

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w09_qp_11.pdf ques 2, 20 , 21, 22 , 23 , 28 , 29 , 31 , 37

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_11.pdf ques 1 , 4 , 6 , 8 , 9 , 10 , 18 , 21 , 29 , 30 , 35 , 38

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_11.pdf ques , 9 , 12 , 20 , 26 , 29 , 35 ,

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_qp_11.pdf ques 8 , 11 , 13 , 23

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_11.pdf ques 8 , 9 , 15 , 16 , 20 , 23, 25 , 36 ,

thats a lot of doubts

May 2004 - Q1 - moles of hydrogen=mass/Mr = 1/2=0.5. *6.02*10^23 to find number of molecules. u get 3.01*10^23molecules. one molecule has 2 atoms so multiply by 2 u get 6.02*10^23 atoms. then find atoms in the options. neon is right as it is one mole and monatomic so it also has 6.02*10^23 atoms.
Q3- moles of NaN3- 50/65= 0.77. mole ratio is 2:3 so 0.77*3/2=1.15 moles of N2. moles=V/24 so V=27.7dm^3
Q9 - A is a weak acid so it wont ionise completely. C is alkali so no H+. D has 2 H+. So answer is B. It is also strong acid and has one H+
Q20- A is like NH3 which is not planar. D is alkane so its not planar. C is alkene but has diff alkyl groups on both sides of C atoms so also not planar.
Q28- Rehydrate all the compound by adding one H and one OH group. A B C all form secondary alcohols which undergo oxidation. Only D forms tertiary alcohol which doesnt get oxidised.

 

[Mairaxo]

Hello everyone
I am new to this part of Xtremepapers cuz i hv just finished my O levels n in these vacations i wanna study for A levels .Although i created a thread but there was no reply. Actually i need the name of the best books for chemistry A levels that most renown skools follow.

Cambridge International AS and A Level Chemistry Coursebook with CD-ROM Author: Norris, R., Ryan, L. and Acaster, D.

 

[Mustafa Malik]

Cambridge International AS and A Level Chemistry Coursebook with CD-ROM Author: Norris, R., Ryan, L. and Acaster, D.

any other ?? I heard about Core Chemistry something

 

[Mairaxo]

any other ?? I heard about Core Chemistry something

I studied from this textbook and it has all you need! I was able to study without a teacher as well and achieve a great score so i definitely recomment this textbook

 

[Mairaxo]

recommend*

 

[Mustafa Malik]

I studied from this textbook and it has all you need! I was able to study without a teacher as well and achieve a great score so i definitely recomment this textbook

the core one or the other u told b4??

 

[Mairaxo]

the core one or the other u told b4??

the one i mentioned earlier

 

[AbbbbY]

Hello everyone
I am new to this part of Xtremepapers cuz i hv just finished my O levels n in these vacations i wanna study for A levels .Although i created a thread but there was no reply. Actually i need the name of the best books for chemistry A levels that most renown skools follow.

I use Roger Norris. Very nice book.

Although, I'll suggest you don't use it yet.

www.chemguide.co.uk
It has every topic very nicely covered. In fact, I use this to understand whatever I get stuck up at.

Also, I'll suggest you use these holidays to do other things instead of studying for your A's. Trust me on this one. I'll suggest
-> An Internship
-> Learn other skills, a foreign language perhaps?
-> Indulge actively in sports, alternatively, take up gymming and keep up with it.
-> If you have even a remote interest in it, take up computer programming, even if it's at a small level
-> Learn to play a music instrument etc.
-> If you plan to apply to the US, and don't want to do any of the above, and want to study, study for the SATI and give it in October, way before everyone else will plan on giving it in your batch. This is particularly helpful because you can then give a retake in Jan after rigorous study again if the need be.

These holidays are the only ones in your life you can truly dedicate time to these things (save for SAT). Don't waste them studying for A Levels. You'll manage that during the next two years aswell. These holidays wont come back, and the ones after your AS/1st year of A Levels will be much tougher and you wont have time for half of that. College essays, personal statements, internships, coursework, where to apply what aptitude tests to take, social work etc etc etc. Too much crap. Trust me.

I regret wasting my O Level holidays sleeping and gaming. I wish I had spent just one hour a day at the gym and one hour a day learning French. Would be in a much different position right now. Glad I did the internship that I did, albeit reluctantly. I dearly wish I had started on the SAT on those holidays. There's nothing in it that an O Level student cant do. The Math is O Level, the English, you won't gain anything stepping even into the second year of A Levels.

I have a lot of regrets on O Level summer. I hope you don't!

Good luck!

 

[h4rriet]

i used pV=nRT but im getting a weird answer :/
and for 30.... in esters doesn't the alcohol come on the right side tho?

Make sure you use the correct units.
It doesn't necessarily have to be on the right or left side; it'll be on the side of the -CO2. For example, an ester will be like this: acid-CO2-alcohol, or alcohol-O2C-acid. The C of the CO2 will be part of the c. acid.

 

[Raiyan3]

bro??!!!
U r wlcm anyways

Hahaha rightt my badd lol!
"oh simple things, where have you gone"

 

[Ahmedraza73]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w12_qp_11.pdf
Can anyone solve Q:11,15,16,17,20