Chemistry: Post your doubts here!

[HorsePower]

No, in D n is the number of moles of the compound XY.

i just got it.... thnx alot

 

[A star]

No, in D n is the number of moles of the compound XY.

can you explain still dont get it

 

[h4rriet]

can you explain still dont get it

In D, the compound ix XY. n is the number of moles, not the number of bonds. There is only one bond in the compound X-Y.

 

[HorsePower]

can you explain still dont get it

think of XYn as CH4.... there are 4 C-H bond to be broken... so we divide the enthalpy change by 4 , to get bond enthalpy of 1 C-H bond

 

[A star]

aah i get it thankyou both

 

[Alice123]

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

 

[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]

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