Chemistry: Post your doubts here!

[papajohn]

I got it ^^ what about Q26

Since it was partial oxidation of the primary alcohol, the aldehyde was produced.
Number of moles of ethanol: 2.30/46 is 0.05
One mole of ethanol produce 1 mole of aldehyde CH3CHO
The theoretical mass of the aldehyde will be 0.05*44 is 2.2 g
The actual mass produce is 70%.

 

[Haya Ahmed]

Since it was partial oxidation of the primary alcohol, the aldehyde was produced.
Number of moles of ethanol: 2.30/46 is 0.05
One mole of ethanol produce 1 mole of aldehyde CH3CHO
The theoretical mass of the aldehyde will be 0.05*44 is 2.2 g
The actual mass produce is 70%.

Ops .. my bad X) .. I thought it is carboxylic acid .. I skipped the word distillation .. anyways thanks

 

[R.M2013]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s09_qp_4.pdf
Q-8 ci) cii) ciii) Anyone please??

 

[NinjaInPyjamas]

Plz if you could specify which part of it , it would be lot easier For Me!

Firstly, for each equation you have to do the working right?

Secondly, I don't get the explanation...with the ratios and all

 

[papajohn]

O/N_2004_P1 -- Q9, Q12, Q13, Q39

M/J _2006_P1 -- Q32

M/J_2011_P12 -- Q8

O/N_2011_P12 -- Q26

M/J_2012_P12 -- Q5 , Q28 , Q36

Please someone help me I'm dying here from confusion !!!

O/N_2004_P1 -- Q9
A is incorrect because there is hydrogen bond exist in alocohol and is stable. The carboxylic and ketoes in options C and D are liquid because of intereating involving induces dipoles. We left with the alkane gas and if you remember, it is only reaction they are good at.

Q12 of same year

Well you can see the affect of temperature here
I stuck on Q39.

 

[Haya Ahmed]

O/N_2004_P1 -- Q9
A is incorrect because there is hydrogen bond exist in alocohol and is stable. The carboxylic and ketoes in options C and D are liquid because of intereating involving induces dipoles. We left with the alkane gas and if you remember, it is only reaction they are good at.

Q12 of same year

Well you can see the affect of temperature here
I stuck on Q39.

Q12 pic can you upload it again because file not found and for Q9 the question is asking about which will release the greatest energy so how did we skip the A, B, C options as they have H-C and C=O bonds which have more enery than those C-H bonds in option B !! I didn't get it

 

[Mohammed salik]

O/N_2004_P1 -- Q9, Q12, Q13, Q39

M/J _2006_P1 -- Q32

M/J_2011_P12 -- Q8

O/N_2011_P12 -- Q26

M/J_2012_P12 -- Q5 , Q28 , Q36

Please someone help me I'm dying here from confusion !!!

M/J _2006_P1 -- Q32
Ans Is B.
1. It says enthalpy change of atomisation, yes we need to Know because Na(s) is converted to Na(g)
2. says Ionisation energy, we need Ionisation energy because it is converted from Na(g)(neutral) to Na(g)(Positive ione)
3. We dont need it because formation if for compounds not elements! So only 1 and 2!!
Hope I Helped!!

 

[papajohn]

Q12 pic can you upload it again because file not found and for Q9 the question is asking about which will release the greatest energy so how did we skip the A, B, C options as they have H-C and C=O bonds which have more enery than those C-H bonds in option B !! I didn't get it

Alkanes are fuel .

 

[papajohn]

 

[Mohammed salik]

O/N_2004_P1 -- Q9, Q12, Q13, Q39

M/J_2011_P12 -- Q8

O/N_2011_P12 -- Q26

O/N_2009_P12 -- Q10 , Q20

M/J_2012_P12 -- Q5 , Q28 , Q36

Please someone help me I'm dying here from confusion !!!

I did explain M/J_2011_P12 - Q8!! What confusion do u Have?

 

[Haya Ahmed]

I did explain M/J_2011_P12 - Q8!! What confusion do u Have?

How did you know that it is liquid or gas want proooooooof for your ans .. can't just take the 1st 10 as gases or whateva ! :S

 

[Mohammed salik]

How did you know that it is liquid or gas want proooooooof for your ans .. can't just take the 1st 10 as gases or whateva ! :S

OK First 4 are gases !
Proof :-http://en.wikipedia.org/wiki/Alkane#Boiling_point
it says : Under standard conditions, from CH4 to C4H10 alkanes are gaseous
Happy

 

[Haya Ahmed]

OK First 4 are gases !
Proof :-http://en.wikipedia.org/wiki/Alkane#Boiling_point
it says : Under standard conditions, from CH4 to C4H10 alkanes are gaseous
Happy

So Much Better

 

[Mohammed salik]

O/N_2004_P1 -- Q9, Q12, Q13, Q39

M/J_2011_P12 -- Q8

O/N_2011_P12 -- Q26

O/N_2009_P12 -- Q10 , Q20, Q28

M/J_2012_P12 -- Q5 , Q28 , Q36

Please someone help me I'm dying here from confusion !!!

O/N_2011_P12 -- Q26
Ethanol is converted to Ehanal (aldehyde)
First find moles of ethanol :-
Moles=mass/Mr
Mass=2.3g..... Mr=46 (C2H5OH)
Moles=0.05
Now find mass of aldehyde:-
Mass=mole * Mr
Mole=0.05...... Mr=44(C2H4O)
Mass=2.2g
But question says yeild is 70%
so 70/100 * 2.2 =1.54 which Is A!!
Hope I Helped!

 

[Mohammed salik]

O/N_2004_P1 -- Q9, Q12, Q13, Q39

O/N_2009_P12 -- Q10 , Q20, Q28, Q34, Q38 , Q40

M/J_2012_P12 -- Q5 , Q28 , Q36

Please someone help me I'm dying here from confusion !!!

M/J_2012_P12 -- Q5 , Q28 , Q36
Q5:-(A) Iodine because it has covalent bonds (I2) and vanderwaals forces!
Q36:-(D)Because haber process is N2 + 3 H2 → 2 NH3 (ΔH = −92.4 kJ·mol−1)
so Forward reaction is exothermic, if u Increase temp yeild goes Down, but Rate increases because Particles gain K.e. So 1 is Correct!
2 says High Pressure decreases yeild, thats wrong because High pressure favours side with less moles which is forward , this would increase yeild.
If 2 is Wrong then option is D! (no need to look at 3)

 

[Mohammed salik]

O/N_2004_P1 -- Q9, Q12, Q13, Q39

O/N_2009_P12 -- Q10 , Q20, Q28, Q34, Q38 , Q40

M/J_2012_P12 -- Q28 , Q36

Please someone help me I'm dying here from confusion !!!

Also Explained 36 . see above!!

 

[Mohammed salik]

O/N_2004_P1 -- Q9, Q12, Q13, Q39

O/N_2009_P12 -- Q10 , Q20, Q28, Q34, Q38 , Q40

M/J_2012_P12 -- Q28

Please someone help me I'm dying here from confusion !!!

O/N_2009_P12 -- Q10 , Q20, Q28, Q34, Q38 , Q40
Q40:- (C) 1. it says one monomer would form polymer? how is that posible? so 1 is wrong then automatically answer is C.
Q38:-C ,Ethanol is oxidized by KMnO4 Not Alumina. so 1 is wrong. then automatically answer is C.

 

[Haya Ahmed]

O/N_2009_P12 -- Q10 , Q20, Q28, Q34, Q38 , Q40
Q40:- (C) 1. it says one monomer would form polymer? how is that posible? so 1 is wrong then automatically answer is C.
Q38:-C ,Ethanol is oxidized by KMnO4 Not Alumina. so 1 is wrong. then automatically answer is C.

Can you explain Question 40 again more briefly please

 

[Mohammed salik]

Can you explain Question 40 again more briefly please

The question says One monomer Would form how many Polymers?
Option 1:- it says One polymer. wrong
One monomer would never form 1 polymer! Polymer is made up of million of Monomers!

 

[Mohammed salik]

O/N_2004_P1 -- Q9, Q12, Q13, Q39

O/N_2009_P12 -- Q10 , Q20, Q34, Q40

M/J_2012_P12 -- Q28

Please someone help me I'm dying here from confusion !!!

O/N_2009_P12 Q34:- C
Because lime and ammonium sulfate react and calcium displaces Ammonia to give calcium sulphate and Ammonia Gas. 1 is wrong So ans IS C