Biology; Chemistry; Physics: Post your doubts here!

[funky brat]

http://papers.xtremepapers.com/CIE/...l O Level/Chemistry (5070)/5070_s13_qp_42.pdf
Question 7, how is the answer to this C? Why not A, I mean keeping the molarity same if we double the volume hydrogen produced will be doubled isn't it?

 

[M.Omar]

The curve is excellent but since the first point starts from 5 cm^3, don't we have to start fromt there and not from (0,14)?

Are these curves flexible

 

[Mahnoorfatima]

http://papers.xtremepapers.com/CIE/...al O Level/Chemistry (5070)/5070_s07_qp_4.pdf
Question 8 part L anyone? I seriously dont get this kind of crap. :/

 

[M.Omar]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s13_qp_42.pdf
Question 7, how is the answer to this C? Why not A, I mean keeping the molarity same if we double the volume hydrogen produced will be doubled isn't it?

Just look at the type of acid they are using.They used H2SO4 and HCL in diff cases..U,ll mostly surly get the idea then

 

[Awesome12]

Are these curves flexible

No they are french curves

 

[M.Omar]

No they are french curves

Oh,so they can they be easily adjusted to make graphs in our chm ATP.I mean it shud be able to draw graphs/curvatures.
Or u draw half of the graph or a part of it using the curves and some part without it

 

[Mahnoorfatima]

SOMEBODY ANSWER MY QUESTION!

 

[peacce]

http://papers.xtremepapers.com/CIE/...l O Level/Chemistry (5070)/5070_w12_qp_42.pdf
Q.8 part l.
tel me how to do this please

 

[peacce]

SOMEBODY ANSWER MY QUESTION!

what is it ?

 

[Mahnoorfatima]

what is it ?

Question 8 part L!

 

[peacce]

tel me how to do this i always get stuck

 

[Uchiha-Sasuke]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s07_qp_4.pdf
Question 8 part L anyone? I seriously dont get this kind of crap. :/

HOOCCxHyCOOH = 118
Cx Hy + 90 = 118
the 90 came from twice COOH Mr
CxHy = 28
Mr CH is always 14 so we divide
28/14 =2
C2H4

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s13_qp_42.pdf
Question 7, how is the answer to this C? Why not A, I mean keeping the molarity same if we double the volume hydrogen produced will be doubled isn't it?

make equations and balance .. you'll get it . It's the moles issue

Uhhh guys a little help with my question ?

 

[Mahnoorfatima]

HOOCCxHyCOOH = 118
Cx Hy + 90 = 118
the 90 came from twice COOH Mr
CxHy = 28
Mr CH is always 14 so we divide
28/14 =2
C2H4

make equations and balance .. you'll get it . It's the moles issue

Uhhh guys a little help with my question ?

14? Why is it always 14? Does it always have to be 14?

 

[peacce]

Here's a trick on making esters
View attachment 42202

trick? what :O

 

[peacce]

14? Why is it always 14? Does it always have to be 14?

why 90.
and how did u get 118 [USER=82593]Uchiha-Sasuke[/USER]

 

[ciesgetoveralready]

tel me how to do this i always get stuckView attachment 42201

Is the answer a?

 

[peacce]

Is the answer a?

Yes

 

[Mahnoorfatima]

tel me how to do this i always get stuckView attachment 42201

Look. First you should know that while drawing an ester you need to remove OH from carboxylic acid and H from OH group of Alcohol.
Second, Draw the Acid and then the alcohol BUT first make the mirror image of alcohol. Like if you have e.g. C-C-O (this is the alcohol having H's and removed H)
So continue the carboxylic acid joing O and then writing C.. Like Carboxylic acid with removed OH - O-C-C-H
Hopefully you got it. :/

 

[Uchiha-Sasuke]

14? Why is it always 14? Does it always have to be 14?

C ---H
12 + 2 =14
always divide by 14

trick? what :O

shit it got corrupted lol xD

 

[Mahnoorfatima]

C ---H
12 + 2 =14
always divide by 14

shit it got corrupted lol xD

But what if the H isn't 2? Sorry but I need to get this!:/