Chemistry: Post your doubts here!

[The Sarcastic Retard]

View attachment 60206
It's B, why?

Are u sure?

 

[Eugene99]

Are u sure?

oh sorry, C

 

[The Sarcastic Retard]

oh sorry, C

Its cos C-Cl bond is weaker than C-F bond.
So C-Cl bond breaks.

 

[Saad the Paki]

I'm confused on how to draw the structural formula for B. I know what it will be.

This is the mark scheme

This is my attempt is it correct?

 

[Rizwan Javed]

I think it should be something like this:
HO2CCH2CH(OCOCH3)CO2H

 

[Saad the Paki]

I think it should be something like this:
HO2CCH2CH(OCOCH3)CO2H

Is it important to be in the order of ' OCO ' ?

 

[Rizwan Javed]

Is it important to be in the order of ' OCO ' ?

Yes, otherwise it will fell like C of the OH group is attached to C if we're writing it like this COO instead of OCO.

 

[ahmedish]

I have never seen such eqaution in As level group I.
Come on tell me, Li + H2O will give you Li2O or Li(OH) ??

I mean group 1 + H2O give hydroxides so thats why

 

[cashew]

http://studyguide.pk/Past Papers/CI... AS Level/9701 - Chemistry/9701_s10_qp_42.pdf
PLEASE, help with Q3 di)

 

[Eugene99]

how is the ester propyl methanoate?

 

[The Sarcastic Retard]

View attachment 60228
how is the ester propyl methanoate?

Methanoic acid + propanol = Propyl methanoate

 

[qwertypoiu]

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9701 - Chemistry/9701_s10_qp_42.pdf
PLEASE, help with Q3 di)

You have to play with the numbers to try to deduce the species responsible for each mass peak. Start with the smallest one and build on from there:

133 - SiCl3

I got this by subtracting various mass numbers from 133 on my calculator and this worked.

Next step is 149, which is 16 away, so just add O:

149 - SiCl3O

Next is 247... That's 98 we have to add. Cl2 gives 70, and Si another 28! So:

247 - Si2Cl5O

Then 263.... That's again a leap of 16:

263 - Si2Cl5O2

Next we have 396... 133 to jump! Get rid of 70 again with Cl2. 63 left. The last digit of 63 is 3, and that could be made by numbers ending with 8 and 5. Basically, 28 + 35 = 63. So we add SiCl3 more:

396 - Si3Cl8O2.

 

[areeba240]

how will we know which compound is oxidised

 

[areeba240]

why cant the anwser be B

 

[areeba240]

helpppppp plzzzzzzzzzz

 

[qwertypoiu]

View attachment 60237
how will we know which compound is oxidised

You have to learn all the organic reactions if you want to answer these kind of questions.
A is dehydration
B is oxidation
C is condensation reaction
D is hydrolysis

 

[qwertypoiu]

View attachment 60238
why cant the anwser be B

In B, the rate remains constant at the end. This is impossible, since the rate MUST reduce to zero eventually since the reaction will eventually finish.

Normal reactions have a rate-time graph like D. However, in this case, the rate of reaction initially increases due to the products that act as catalysts, and then eventually the shape comes back to normal as the reactants become fewer and collisions rarer. (C)

 

[qwertypoiu]

View attachment 60239
helpppppp plzzzzzzzzzz

I don't have a calculator right now but the answer should be D I think.

Mr of CH4 is 16, which is much higher than that of H2 or He. So just look at the planet with largest amount of methane.

 

[Dark Destination]

You have to learn all the organic reactions if you want to answer these kind of questions.
A is dehydration
B is oxidation
C is condensation reaction
D is hydrolysis

How is A dehydration? :3

 

[qwertypoiu]

How is A dehydration? :3

Alcohols are dehydrated using concentrated acid catalyst.