Chemistry: Post your doubts here!

[Aymen Ezazi]

oh ok thanks , so the ideal gas equation can actually be used for any gas ?

yes it can be..

 

[Aymen Ezazi]

9701_s09_qp_1.pdf
q 40 someone pleaseee explaainn!!

the bond will be broken from CO2 thats where the Na from NaOH will bond to oxygen.. it will not be 3 bcoz they have taken out the alkene completely so its wrong.. 2 is correct bcoz Na is bonded to O and the rest of the molecule is ok.. so definetly its going to be 1 also.. bcoz there is no option just for 2.. but u can still check it.. see if all the bonds are presnt or not and with OH which comes from NaOH

 

[A star]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w09_qp_11.pdf Q21
Jiyad Ahsan daredevil littlecloud11 A star please

C?

 

[Alice123]

C?

A

 

[ShaanSiddiq090909]

the bond will be broken from CO2 thats where the Na from NaOH will bond to oxygen.. it will not be 3 bcoz they have taken out the alkene completely so its wrong.. 2 is correct bcoz Na is bonded to O and the rest of the molecule is ok.. so definetly its going to be 1 also.. bcoz there is no option just for 2.. but u can still check it.. see if all the bonds are presnt or not and with OH which comes from NaOH

Thanks .. but can you explain it a bit more coz I still didn't understand why did the bond from CO2 break!

 

[Aymen Ezazi]

Thanks .. but can you explain it a bit more coz I still didn't understand why did the bond from CO2 break!

bcoz the only electronegative atom in this molecule is O, so Na can bond only to oxygen and no other atom..

 

[carilove]

hey guys need help with http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s05_qp_1.pdf question 1 and 2 ​

thanks​

 

[A star]

A

hmm :/

 

[moinul]

can anyone plz advice me or tell "is solving 1000 mcq effective for p1 exam"?

 

[daisyy]

Hey guys i need help in question number 20 in http://www.freeexampapers.com/index...evel/Chemistry/CIE/2003 Jun/9701_s03_qp_1.pdf pleaase help!!

 

[syed1995]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w09_qp_11.pdf Q21
Jiyad Ahsan daredevil littlecloud11 A star syed1995 PANDA- please

That question is f`d up.. totally went over my mind. Need help in this...

 

[Alice123]

hmm :/

http://papers.xtremepapers.com/CIE/Cambridge International%

20A%20and%20AS%20Level/Chemistry%20(9701)/9701_w09_qp_11.pdf

Some1 did dis b4... im tryin to understand..

 

[Alice123]

That question is f`d up.. totally went over my mind. Need help in this...

see d above post

 

[cute97]

answer is B
amount of sulphite use = conc x vol
= 0.1 x (25/1000)
=2.5x10^-3mol
2 electrons are lost
amount of electrons lost = 2 x 2.5 x 10^-3 ==== 5 x 10^-3 mol
amount of electorns gained by metallic salt = amount of electrons lost by sulphite
= 5 x 10^-3 mol
amount of metallic salt used = 0.1 x (50/1000) ==== 5 x10^-3
amount of electrons gained PER MOLE of salt = (5 x 10^-3)/(5x10^-3) = 1 unit
hence oxidation state of metallic salt decreases by 1 unit meaning the oxidation satate becomes +2 from +3!!! this is for the question 9 , some other person posted it

Thankss but i never saw such a working i think my teacher missed explaining or wat

 

[A star]

see da above post

i got it look
remove a aldehyde group and the ring you are left with C13 H26 now acording to alkene general formulae there should have been 26 hydrogen as each double bond removes two hydrogen two double bond will remove the hydrogen . hence three double bond in cyclo hexene and 2 extra makes 5 hence A syed1995 daredevil

 

[daisyy]

quote="Alice123, post: 607701, member: 44056"]see da above post[/quote] can any of you help in the question i posted above? Thanks

 

[ShaanSiddiq090909]

9701_s09_qp_1.pdf
Can someone please help me with q 25
why is the answer B? reason...

 

[felicia tan]

Use of the Data Booklet is relevant to this question.
Ethyl ethanoate can be obtained from ethanoic acid and ethanol by the following reaction.
CH3CH2OH + CH3CO2H CH3CO2CH2CH3 + H2O
Ethanol (30 g) and ethanoic acid (30 g) are heated under reflux together, and 22 g of ethyl
ethanoate are obtained.
What is the yield of the ester?

Please help!! thankyou

 

[daredevil]

Hay there,

Thanks for helping out, but its still not solved
Option B has H and H on both sides.. (not H and Cl, if that would been, then it would be a sure answer, but its not like that)
Option C has Cl and Cl on both sides..


And I'll be grateful if you explain the question number 10 of the same paper. Why its answer is C, whats wrong in B ??\

Regards

no no on the left side it has O and on the right it has H in B part. in C it has O on one side and Cl on the other side. that is what i meant by OPPOSITE poles. thus dipoles are formed.

in B of q10 the activation energy is really high so the reactoin will take a long time to proceed bcz it will need more time to attain such a high amount of energy tto activate the reaction.

 

[Ikram Khaliq]

which physical state has the greatest potential energy?