Chemistry: Post your doubts here!

[!>@/^~^\@<!]

basically over here, room temperature is taken to be "cold conditions" {cold dilute acidified manganate (VII) solution} and under harsher conditions "Hot conditions" is taken to be higher temperatures {hot, concentrated manganate (VII) solution}.

No i was talking about the addition reaction of alkenes (addition of hydrogen halide) not oxidation reaction of alkene...

 

[aalmuhannadi]

C is an ester, not a carboxylic acid.

How do you figure it's an ester? isn't the middle carbon bonded to the left-hand carbon, which has a double bond with oxygen and -OH?

 

[darknessinme]

How do you figure it's an ester? isn't the middle carbon bonded to the left-hand carbon, which has a double bond with oxygen and -OH?

The middle carbon is bonded to the O of the ester group. The compound is made from formic acid reacting with, 1-bromopropan-2-ol to form the ester. Try draw the displayed formula.

 

[aalmuhannadi]

The middle carbon is bonded to the O of the ester group. The compound is made from formic acid reacting with, 1-bromopropan-2-ol to form the ester. Try draw the displayed formula.

Yeah I figured out how to draw it now but how would you tell from its structural formula that it was an ester though? I'm not aware of how it's formed and I don't think you need to know that from the syllabus...

 

[scouserlfc]

i neeed help ! AS questions..

How many isomers with the formula C5H10 have structures that involves pi bonding?
A 3 B 4 C 5 D6

The ans is D !

Its quite easy use chain isomerism + positional isomerism these are basically forms of structural isomerism !
1. CH3CH2CH2CH=CH2
2.CH3CH2CH=CHCH3 + (this is a cis if u keep H on the same side of double bond but trans when different )
3.CH3CH2C(CH3)=CH2
4.CH3CH=C(CH3)CH3
5.CH3CH(CH3)CH=CH2

so here u go 6 isomers !

 

[scouserlfc]

Yeah I figured out how to draw it now but how would you tell from its structural formula that it was an ester though? I'm not aware of how it's formed and I don't think you need to know that from the syllabus...

Actually u need to know how its formed plus some of its conditions and u can easily identify it if u see this group in structural formula ! -COO- or -CO2-
the - meaning its joined to the chain with mostly alcohol in front and Carboxylics chain at the back !

 

[aloha]

does anyone has this guuide!!!!

 

[Student12]

Its quite easy use chain isomerism + positional isomerism these are basically forms of structural isomerism !
1. CH3CH2CH2CH=CH2
2.CH3CH2CH=CHCH3 + (this is a cis if u keep H on the same side of double bond but trans when different )
3.CH3CH2C(CH3)=CH2
4.CH3CH=C(CH3)CH3
5.CH3CH(CH3)CH=CH2

so here u go 6 isomers !

Thanks.. i didnt take the cis trans into consideration.

 

[sweetiepie]

Tips For 31-40 (Chemistry MCQ's Paper 1)

. If 1st choice is obviously incorrect, the answer is automatically C.
. If 2nd choice is obviously incorrect the answer is automatically D.
. If 3rd choice is incorrect and 2nd choice is correct the answer is B.
. If 1st choice and 3rd choice are right the answer is A.

hope this helps

 

[Dukeofwin]

Tips For 31-40 (Chemistry MCQ's Paper 1)

. If 1st choice is obviously incorrect, the answer is automatically C.
. If 2nd choice is obviously incorrect the answer is automatically D.
. If 3rd choice is incorrect and 2nd choice is correct the answer is B.
. If 1st choice and 3rd choice are right the answer is A.

hope this helps

Given the fact you wrote all that, I'll say a Big Thanks! But thats a bit too obvious isnt it? No Offence but its like saying 'if you think A and C are wrong then your answer will either be B or D'

 

[sweetiepie]

Given the fact you wrote all that, I'll say a Big Thanks! But thats a bit too obvious isnt it? No Offence but its like saying 'if you think A and C are wrong then your answer will either be B or D'

what u mean

 

[Dukeofwin]

what u mean

Nevermind! You were a big help. Thanks :/

 

[sweetiepie]

Nevermind! You were a big help. Thanks :/

Welcome

 

[Silent Hunter]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w09_qp_41.pdf

How to do question 7 (c) (ii) ? JazakAllah

 

[unseen95]

please help me with question number 28 of 9701/01/M/J/04 with reason.

 

[scouserlfc]

please help me with question number 28 of 9701/01/M/J/04 with reason.

First remove the formula of benzene from the molecular formula here it is C6H5 so now u have C4H9O which is an alcohol (this differs from the general alcohol formula because one C is bonded to benzene rather than the H ) Now lets see the next requirement it doesnt have to react with mild [O] so basically its a tertiary alcohol ! SO A and B are wrong as they have no side chain ,Now in C its quite obvious that its not the answer as the double bond forms on carbon no 3 from benzene which is wrong as whenever dehydration occurs the OH is removed plus another H is removed from the carbon next door to the OH bonded Carbon and thats not the case so D is the answer !

 

[youssef 98]

do u hve the chemistry oct/nov 2013 papers?

 

[iKhaled]

do u hve the chemistry oct/nov 2013 papers?

we don't even have may/june 2013 yet...

 

[snowbrood]

step 1 if option a is not correct then either option b c or d is correct else go to step 4
step2 if b is also not correct then either option c or d is correct else go to step 4
step 3 if c is also not then d is correct else go to step 4
step 4 that is correct answer
hope that helps it always works for me from mcq 1 to 40

 

[asd]

Asalam alaikum brother.
Is the answer A?
In questions like these you have to keep in mind ALL the products that would be produced if the reactant is mixed separately with the substance in the options and all the required conditions are met.
I'll start with the incorrect one's first.
B) HCl; keeping our knowledge of organic chemistry in mind, this will be an addition reaction, in which the double bond will be changed into a single bond, giving room for the H and Cl to attach to DIFFERENT carbon atoms.
The products will be:
-> CH2CCl3
-> CHCl2CHCl2
Neither are chiral, lets move on to C.
C) NaCN; this would again lead to an addition reaction (nucleophilic), but if memory serves me, it only happens when there is a carbonyl group attached to a carbon atom. Incorrect.
D) NaOH; again, a nucleophilic substitution will occur BUT the C-C double bond will still remain, and for a carbon atom to be chiral it MUST have 4 different alkyl groups/atoms attached to it. Incorrect.

Now for the correct option, A.
Br2.
This will be an electrophilic addition reaction which involves the forming of a carbon cation thus resulting in the breaking to the double bond.
The only product will be:
-> CHClBrCCl2Br
Which is indeed chiral.

Do forgive me if I wrote anything incorrect. Allah knows best.

For B, two products will be formed? How will CH2CCl3 be formed?