Chemistry: Post your doubts here!

[ashcull14]

It has the most number of C-Cl bonds which persist high up in the atmosphere and break to form chlorine free radicals that deplete the ozone layer ... C-H bonds will break sooner once released into the atmosphere ... and C-F bonds are stable so they dont break as easily.

thnks

 

[awesomaholic101]

Oh hahaha I didn't know polyethene did that

different samples of polymers can have different no. of monomers to make it up ... the longer the chain, the greater the melting point .... thus the range

thnks

no problem

 

[mahlom]

different samples of polymers can have different no. of monomers to make it up ... the longer the chain, the greater the melting point .... thus the range


no problem

Bro how to solve Oct nov 2014 Q 30 plz

http://maxpapers.com/syllabus-materials/chemistry-9701-a-level/attachment/9701_w14_qp_11/
My answer is 8 though its not in the marking scheme

 

[goldenkatana]

Can You help me with number 39 & 40?

 

[awesomaholic101]

Bro how to solve Oct nov 2014 Q 30 plz

http://maxpapers.com/syllabus-materials/chemistry-9701-a-level/attachment/9701_w14_qp_11/
My answer is 8 though its not in the marking scheme

See, the molecule given has a lot of C=C bonds ... but only the tertiary alkenes will oxidise to give ketones ... (the secondary alkenes will oxidise to give aldehyde which further get oxidised to form acids. The primary ones give CO2) ... tertiary alkenes is when a C in the C=C double bond is attached to 3 other Carbon atoms ... if u look at the molecule carefully, u will see that there are 6 tertiary alkenes.

 

[awesomaholic101]

See, the molecule given has a lot of C=C bonds ... but only the tertiary alkenes will oxidise to give ketones ... (the secondary alkenes will oxidise to give aldehyde which further get oxidised to form acids. The primary ones give CO2) ... tertiary alkenes is when a C in the C=C double bond is attached to 3 other Carbon atoms ... if u look at the molecule carefully, u will see that there are 6 tertiary alkenes.

and oh! i am a girl

 

[goldenkatana]

 

[awesomaholic101]

Can You help me with number 39 & 40?View attachment 54830

only the 39th question is in the picture ...
Is the answer B? If so, then ...
alkaline (NaOH in this case) hydrolisis of ester has 2 products: the sodium salt of the acid and the alcohol ...
and the first part of the molecule where the C is double bonded to O becomes the salt of acid ... the other part becomes the alcohol.

 

[mahlom]

See, the molecule given has a lot of C=C bonds ... but only the tertiary alkenes will oxidise to give ketones ... (the secondary alkenes will oxidise to give aldehyde which further get oxidised to form acids. The primary ones give CO2) ... tertiary alkenes is when a C in the C=C double bond is attached to 3 other Carbon atoms ... if u look at the molecule carefully, u will see that there are 6 tertiary alkenes.

Thanks

 

[awesomaholic101]

View attachment 54831

40th question ... is the answer D?

 

[nehaoscar]

How +2??

 

[princess Anu]

Reaction of aldehydes with HCN require Reflux OR it occurs at RTP?

 

[shazmina]

Help Please!!!
Use of the Data Booklet is relevant to this question. Sir Humphrey Davy discovered boron, calcium, magnesium and sodium. Which of these elements has the second smallest atomic radius in its group and the third lowest first ionisation energy in its period?
A boron
B calcium
C magnesium
D sodium

The Ans is C

 

[goldenkatana]

40th question ... is the answer D?

I think it its C.

 

[mahlom]

See, the molecule given has a lot of C=C bonds ... but only the tertiary alkenes will oxidise to give ketones ... (the secondary alkenes will oxidise to give aldehyde which further get oxidised to form acids. The primary ones give CO2) ... tertiary alkenes is when a C in the C=C double bond is attached to 3 other Carbon atoms ... if u look at the molecule carefully, u will see that there are 6 tertiary alkenes.

But If you count again you will find out that there are 8 tertiary carbon atoms !!
Try

 

[nehaoscar]

different samples of polymers can have different no. of monomers to make it up ... the longer the chain, the greater the melting point .... thus the range


no problem

Oh i see! Thankyou!

 

[nehaoscar]

How +2??

 

[awesomaholic101]

I think it its C.

uhm ... option 3 is wrong because the initial reactant isn't an ester ... only esters have this alkaline hydrolysis thingy to produce salt of acid ... nd 2nd option, i've never come accross it ... first is right coz the O-H bond will break and Na will take the place of hydrogen ...
but i am not sure ... if you know which year the paper is, plz do check the ms and lemme kno ...

 

[nehaoscar]

What would A give? why is A wrong?

 

[nehaoscar]

Do alkenes not react with NaBH4??