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Chemistry: Post your doubts here!

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ull get CO2. u can also have it in a carbonate compound. depending on the reagent added like KOH or NaOH (any basic). since here NaOH was used so it can be NaCO3

Ans: NaCO3 /CO2
since there is an amine group due to hydrolysis(breaking bonds) it'll break apart n be in ion state or can be in amine compound which r stable enough.
so it may be CH3NH3+ Cl- or CH3NH2 (amine)

moreover, theres the aryl group there. so due to hydrolysis...the R group is seperated leaving the aryl group. i wont call it phenol exactly coz theres 2 rings joined there. so generalising it ...it becomes an aryl


in short answer : CH3NH3+Cl- and CO2 and the aryl with a phenol nxt to it (means one ring will have OH group on carbon 1)
 
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Hi guys. Can you help me on a few past year questions? (ON 2013 P13)
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w13_qp_13.pdf
3. A 10cm3 sample of 0.30moldm–3 Tl+NO3– required 20cm3 of 0.10moldm–3 acidified NH4VO3 to oxidise it to Tl3+ in solution. Vanadium is the only element reduced in this reaction.
What is the oxidation number of the vanadium in the reduced form?
A +1 B +2 C +3 D +4
Ans: B

15. Ammonia exists as simple covalent molecules, NH3. Ammonia can react with suitable reagents to form products containing ammonium ions, NH4+. Ammonia can also react with suitable reagents to form products containing amide ions, NH2–.
Which of these nitrogen-containing species are present in an aqueous solution of ammonia?
A ammonia molecules, ammonium ions and amide ions
B ammonia molecules and ammonium ions only
C ammonia molecules only
D ammonium ions only
Ans: B

23. Pent-2-ene, CH3CH2CH=CHCH3, reacts in a similar way to ethene.
Pent-2-ene is reacted with cold, dilute, acidified manganate(VII) ions.
What will be produced in the greatest amount?
A CH3CH2CH(OH)CH(OH)CH3
B CH3CH2COCOCH3
C a mixture of CH3CH2CH(OH)CH2CH3 and CH3CH2CH2CH(OH)CH3
D CH3CH2COOH and CH3COOH
Ans: A

27. An alcohol with molecular formula CnH2n+1OH has a chiral carbon atom but does not react with
hot, acidified K2Cr2O7.
What is the smallest possible value for n?
A 5 B 6 C 7 D 8
Ans: C

38 The reaction of ethanal, CH3CHO, with HCN to form a cyanohydrin is catalysed by NaCN.
What are features of the intermediate of this reaction?
1 It is chiral.
2 It has a single negative charge on one of its atoms.
3 It is a nucleophile.
Ans: A (1,2,3)

39 The ester C2H5CO2CH2CH2CH3 can be made in a school or college laboratory by a sequence of
reactions using compound X as the only organic material.
What might be the identity of compound X?
1 CH3CH2CH2OH
2 CH3CH2CHO
3 CH3COCH3
Ans: B(1,2)


Hope you could provide me steps/explanations to these questions(Whichever you could help with)ASAP. Thanks! :)

 
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Hi guys. Can you help me on a few past year questions? (ON 2013 P13)
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w13_qp_13.pdf
Hope you could provide me steps/explanations to these questions(Whichever you could help with)ASAP. Thanks! :)

Q3.
Ti+ --> Ti3+ + 2e-

moles of Ti+ : moles of e- : moles of VO3-
0.003 moles : ? : 0.002 moles
3 moles : ? moles : 2 moles

Using the half equation, we can see that 3 moles of Ti+ will transfer 6 moles of electrons to 2 moles of VO3-.

In other words, 1 mole of VO3- gains 3 moles of electrons (its oxidation number would decrease by 3 units).

Original oxidation number of vanadium in VO3- is +5, final oxidation number would then be +2 (since it decreases by 3 units).

Q15.
NH3 is a stronger base than H2O, so we have NH3 accepting protons from H2O

NH3 + H2O <--> NH4+ + OH-

Q23.
Using cold dilute KMnO4, we will add OH to each of the carbons across the C=C double bonds.

Q27.
It should be a tertiary alcohol as it is not oxidized. The carbon holding the OH is expected to be joined to 3 other branches containing different number of carbons.

......C
C2-C-C3
.....OH

Q38. Which option are you unsure of? See if you can google for the mechanism of the reaction.

Q39.
Option 1 is correct
CH3CH2CH2OH (alcohol) can be oxidized to CH3CH2CO2H (acid)
CH3CH2CH2OH (alcohol) and CH3CH2CO2H (acid) can undergo esterifcation to form the desired product.

Option 2 is correct
CH3CH2CHO (aldehyde) can be oxidized to CH3CH2CO2H (acid)
CH3CH2CHO (aldehyde) can be reduced to CH3CH2CH2OH (alcohol)
CH3CH2CH2OH (alcohol) and CH3CH2CO2H (acid) can undergo esterifcation to form the desired product.
 
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ull get CO2. u can also have it in a carbonate compound. depending on the reagent added like KOH or NaOH (any basic). since here NaOH was used so it can be NaCO3

Ans: NaCO3 /CO2
since there is an amine group due to hydrolysis(breaking bonds) it'll break apart n be in ion state or can be in amine compound which r stable enough.
so it may be CH3NH3+ Cl- or CH3NH2 (amine)

moreover, theres the aryl group there. so due to hydrolysis...the R group is seperated leaving the aryl group. i wont call it phenol exactly coz theres 2 rings joined there. so generalising it ...it becomes an aryl


in short answer : CH3NH3+Cl- and CO2 and the aryl with a phenol nxt to it (means one ring will have OH group on carbon 1)
Thanks :) appreciated :)
 
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