Chemistry: Post your doubts here!

[Gehad Mohamed]

Hello! Can someone please explain how to solve Q 3 Q10 Q29 why not C ! Q39
http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w02_qp_1.pdf

 

[Gehad Mohamed]

Hello! Can someone please show me the angles by drawing them

 

[Metanoia]

Hello! Can someone please explain how to solve Q 3 Q10 Q29 why not C ! Q39
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w02_qp_1.pdf

Q3. I don't have the data booklet at hand now, but you can look it up and add the 1st and 2nd IE of Al. Then see which of the 4 options give then same total value as Al.

Q10. D: Combustion of CH4 to CO2 and H2O is exothermic, so is the formation of N2 due to forming of triple bonds.

Q29. Option C is actually an ester bond on the left, not an acid functional group.

Q39.
Ethanol acts as base and gains proton to form CH3CH2OH2+
Conc H2SO4 acts as an acid and loses proton to form HSO4-
So statement 2 and 3 are correct

 

[Metanoia]

Hello! Can someone please show me the angles by drawing them

Qn is asking for bond energy, not bond angle.

I believe it should be C-Cl, but better check the data booklet to be sure.

 

[Gehad Mohamed]

Q3. I don't have the data booklet at hand now, but you can look it up and add the 1st and 2nd IE of Al. Then see which of the 4 options give then same total value as Al.

Q10. D: Combustion of CH4 to CO2 and H2O is exothermic, so is the formation of N2 due to forming of triple bonds.

Q29. Option C is actually an ester bond on the left, not an acid functional group.

Q39.
Ethanol acts as base and gains proton to form CH3CH2OH2+
Conc H2SO4 acts as an acid and loses proton to form HSO4-
So statement 2 and 3 are correct

Thanks alot

 

[Gehad Mohamed]

Qn is asking for bond energy, not bond angle.

I believe it should be C-Cl, but better check the data booklet to be sure.

Opps I misread the question thanks

 

[xXEleminatorXx]

Can any one explain how SO2 inhibits aerobic bacteria in preserving food?
And also the concept of dipole moment!

 

[Gehad Mohamed]

Hi ! Can someone please explain q 12 why no change in rate and hydrogen evolved when 40cm^3 is used ?! Concentration is more right so at least the rate will increase! !!
http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w02_qp_1.pdf

 

[kitkat <3 :P]

Hi ! Can someone please explain q 12 why no change in rate and hydrogen evolved when 40cm^3 is used ?! Concentration is more right so at least the rate will increase! !!
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w02_qp_1.pdf

is the answer B ?

 

[Gehad Mohamed]

is the answer B ?

Yea it should be B

 

[kitkat <3 :P]

Yea it should be B

what s in the markscheme

 

[Gehad Mohamed]

Can any one explain how SO2 inhibits aerobic bacteria in preserving food?
And also the concept of dipole moment!

Use of so2 in food preservation : So2 since is bacteriostatic, is used in food preservation. Its reducing character when moist helps it to be used as a food preservative. They (so2 and sulphides) inhibit the oxidation of food compounds eg:unsaturated fats and also act as acids to restrict the growth of molds and aerobic bacteria.

Dipole moment is the shifting of shared electron pair towards more electronegative elements.
More electronegative elements like (F , O , N , Cl , S , P, Br)

Note that hydrogen and carbon are less electronegative elements and the difference between them are not much and is not significant.

 

[Gehad Mohamed]

what s in the markscheme

Its B now am asking why B not D

 

[kitkat <3 :P]

Its B now am asking why B not D

because the concentration of the limiting reactant is not changing

 

[omarjaved619]

HELP! Answer is C. Does it have something to do with the proportions of the acid and base?

 

[Metanoia]

because the concentration of the limiting reactant is not changing

Actually, since the limiting reactant here is zinc (solid), it so would be more correct to use "mass or moles" being the same between the two experiments rather than "concentration"

Its B now am asking why B not D

The is no change in the

1) particle size of solid reactant (zinc)
2) concentration of the aqueous reactant (acid)
3 )initial temperature of reaction

 

[Metanoia]

View attachment 44033

HELP! Answer is C. Does it have something to do with the proportions of the acid and base?

Heat of neutralization for strong acids and strong alkali is estimated to be -57kJ PER MOLE of H2O formed.

For both experiments. (Involving strong acid and bases) , it reflects twos moles of water formed .

So heat of reaction is -57 x 2 for both equations.

 

[Gehad Mohamed]

because the concentration of the limiting reactant is not changing

Ok thanks a lot

 

[Gehad Mohamed]

Actually, since the limiting reactant here is zinc (solid), it so would be more correct to use "mass or moles" being the same between the two experiments rather than "concentration"


The is no change in the

1) particle size of solid reactant (zinc)
2) concentration of the aqueous reactant (acid)
3 )initial temperature of reaction

Thank you so much

 

[omarjaved619]

Heat of neutralization for strong acids and strong alkali is estimated to be -57kJ PER MOLE of H2O formed.

For both experiments. (Involving strong acid and bases) , it reflects twos moles of water formed .

So heat of reaction is -57 x 2 for both equations.

Thanks a lot!