Chemistry: Post your doubts here!

[Eugene99]

Well I didn't really check but perhaps 10 minutes? This one was slightly longer because I wanted to explain in detail since I knew last year others had this issue as well. This way next time someone asks this question again I can just link them to this answer
There have been so many questions asked and answered on this thread over the years that I think there should be some page where the answers are somehow organized in such a way that if, for example, I was having trouble with q6 of ON 2007 paper 1, I could quickly see if someone has previously answered it. Though it seems difficult

https://www.xtremepapers.com/commun...st-your-doubts-here.9859/page-462#post-812038
found another solution, post#9221 here ...used trial and error

 

[qwertypoiu]

It doesn't always give all the possible pages.I've tried it.Googling is better as per my experience. :/

Yes I usually google.

One thing you can do is to search:

site:xtremepapers.com/community <some other search terms here>

Then it looks it up in this site

 

[My Name]

Yes I usually google.

One thing you can do is to search:

site:xtremepapers.com/community <some other search terms here>

Then it looks it up in this site

Yep I do that.

 

[Eugene99]

qwertypoiu that post#9221, the guy also answered q18 but he said HCl will not react KI, but I would say KCl and HI will form, won't they?
this is the question paper:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s12_qp_11.pdf
it's 18th one

 

[Eugene99]

hydrolysis of ethyl propanoate will give CH3CH2OH, Mr=46
and CH3CH2COOH, Mr=74
percentage of OH, therefore will be 46/120 x100 =38.3%
and for the acid, 74/120 x 100=61.7%
but the answer isn't B, it's A!! What went wrong now?? :3

 

[ahmedish]

Its Li3N + H2O not Li3N + O2
Li3N + 3H2O ----> 3Li(OH) + NH3
4Li3N + 3O2 ⇄ 6Li2O + 2N2

stupid question... where do we know this from? AS syllabus in the group 1 reactions right?

 

[The Sarcastic Retard]

View attachment 60184
hydrolysis of ethyl propanoate will give CH3CH2OH, Mr=46
and CH3CH2COOH, Mr=74
percentage of OH, therefore will be 46/120 x100 =38.3%
and for the acid, 74/120 x 100=61.7%
but the answer isn't B, it's A!! What went wrong now?? :3

It will be CH3CH3COONa

 

[qwertypoiu]

qwertypoiu that post#9221, the guy also answered q18 but he said HCl will not react KI, but I would say KCl and HI will form, won't they?
this is the question paper:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s12_qp_11.pdf
it's 18th one

Well it's basically just a solution of Cl- and I- ions, with K+ and H+ ions. No matter which combination you consider, no form of precipitation occurs, nor do any of the ions cause a color. So it will be transparent. When mixing ions just results in a solution of the ions without any change in oxidation states or precipitation, we say no reaction occurred. That's what Metanoia meant.

 

[The Sarcastic Retard]

stupid question... where do we know this from? AS syllabus in the group 1 reactions right?

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

 

[Eugene99]

It will be CH3CH3COONa

oh!! yes!! thankyou

 

[The Sarcastic Retard]

oh!! yes!! thankyou

Anytime.. ^_^

 

[funky brat]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s15_qp_41.pdf
Question 2 b. How is the compound Q formed?

 

[The Sarcastic Retard]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s15_qp_41.pdf
Question 2 b. How is the compound Q formed?

From R you can see that the structure of Q will be similar to it.
Think about it.
You will get an idea that two H from amine and two cl from acyl chloride will be removed.
Then you can think like the picture above.

 

[funky brat]

part 3 anyone?
Also in part 1 why is the process hydrogenation? Why can't it be reduction?

 

[funky brat]

View attachment 60188
From R you can see that the structure of Q will be similar to it.
Think about it.
You will get an idea that two H from amine and two cl from acyl chloride will be removed.
Then you can think like the picture above.

Thanks I got it. Can you help with the other question too?

 

[funky brat]

Anyone?

 

[funky brat]

what's the explanation?

 

[The Sarcastic Retard]

Anyone?

8?

 

[funky brat]

8?

Nope. 3 :/

 

[The Sarcastic Retard]

Nope. 3 :/

Cis, Trans, and other will be shifiting of that R-O-CH2-O-R. Not sure. :3