Chemistry: Post your doubts here!

[mahabaloch]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w07_qp_1.pdf
Plz help with Q1, 10, 19 and 37

 

[salvatore]

I'm having problems with drawing the primary, secondary and tertiary structures of proteins. As in, I don't know how to draw simplified structures for these. Here are two examples:
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w11_qp_42.pdf
qn 6(b)ii

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w09_qp_42.pdf
7(a)

I'll be really grateful for any help given, preferably the diagrams drawn for me.
Thanks a lot

 

[sidbloom1995]

help plzz

9701.mj.06 q, 25
9701.on.06 q,37,3
9701.mj.01 q 34,26,
9701.on.07 q 33,37,4
9701.mj.08 q 27 ,
9701.on.09 ( varient 11) 28,24,21
9701.on.10(varient 12) 39,27,13
9791.0n.10 (varient 11) q 38 ( what product will form if tollen reagent react with it ),35,29
9701.mj.10 (varient 11) q 12,
9701.mj.11(varient 12) q 38,29,28,24,11,
*9701.mj.11(varient 11) q 36,27,34,26,16
9701.on.11.(varient 12) q 9
9701.on.11 (varient 11) q 27,29,21,
9701.mj.12, (varient 12) q 24,23
9701.mj.12 (varient 11) q 29,23,22,9,
9701.on.12 (varient 11) q 26,

O/N 2010 -12-
Q13. Answer is B
the balancing of our equation is
5HIO ---------> 2[I2] + 1 [HIO3] + 2[H2O]
thus our answer will be B

Q27. this one im not entirely sure of the reasoning
the answer is A because our compound is an ester and with treatment to acid, the ester breaks to carboxylic acid and alcohol
our product will be an acid!
H2 will not react with acid
so our product will only be an acid!

Q39. Answer is A
they gave us 74 g of each substance
74g is also the Mr of each one of these substances
calculate the Mr of each of the product
Mr of Butanone is 72g
Mr of butanoic acid is 88g
Mr of 2-methylpropanoic acid is 88g
now divide the mass of each of the products formed with there Mr
for Butanone = 44.64 / 72 = 0.62
for butanoic acid = 54.56 / 88 = 0.62
for 2-methylpropanoic acid = 54.56 / 88 = 0.62
thus all of them form 62% of product

O/N 2010 -11-
Q. 38 Answer is B because 1 and 2 are correct! explanation in the pics

 

[sidbloom1995]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w07_qp_1.pdf
Plz help with Q1, 10, 19 and 37

except for 37 i answered the rest of them
did you not understand the explanation?

 

[♣♠ Magnanimous ♣♠]

EMPERICAL

 

[sidbloom1995]

I'm having problems with drawing the primary, secondary and tertiary structures of proteins. As in, I don't know how to draw simplified structures for these. Here are two examples:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_42.pdf
qn 6(b)ii

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w09_qp_42.pdf
7(a)

I'll be really grateful for any help given, preferably the diagrams drawn for me.
Thanks a lot

seondary structure consist of hydrogen bondings being formed between -CO and -NH group
they form either alpha helix of beta plated structures

the tertiary structure consist of 4 types of bondings
1. Hydrogen bonging
2. ionic bond between opositely charged groups
3. van der waals forces between hydrophobic R groups
4. disulphide covalent bridges (-S-S-), it's only formed between cystine molecules, as they are the only ones that have S in them

Primary structure only consist of arengements of aminoacids

 

[sidbloom1995]

View attachment 38889
EMPERICAL

can you post the MS!
thanks

 

[♣♠ Magnanimous ♣♠]

can you post the MS!
thanks

WHAT IS your answer..
No answer

 

[♣♠ Magnanimous ♣♠]

 

[sidbloom1995]

help plzz

9701.mj.06 q, 25
9701.on.06 q,37,3
9701.mj.01 q 34,26,
9701.on.07 q 33,37,4
9701.mj.08 q 27 ,
9701.on.09 ( varient 11) 28,24,21
9701.on.10(varient 12) 39,27,13
9791.0n.10 (varient 11) q 38 ( what product will form if tollen reagent react with it ),35,29
9701.mj.10 (varient 11) q 12,
9701.mj.11(varient 12) q 38,29,28,24,11,
*9701.mj.11(varient 11) q 36,27,34,26,16
9701.on.11.(varient 12) q 9
9701.on.11 (varient 11) q 27,29,21,
9701.mj.12, (varient 12) q 24,23
9701.mj.12 (varient 11) q 29,23,22,9,
9701.on.12 (varient 11) q 26,

O/N 2010 -11-
Q29. (sorry i didnt see it before) the ans is C because we will have 3 structures
2 will be from -cis and -trans
one will be a simple carbon chain of 4 carbons, butene!

Q35. sorry i dont know for 3 in this i'll tell u about it if i find anything!

 

[sidbloom1995]

WHAT IS your answer..
No answer

im sorry but im not confident enough to post my answer without confirmation!
i'll tell you the answer and if it is right, i'll post the procedure! it's CHO just!

 

[daredevil]

View attachment 38889
EMPERICAL

the method's right... but cant seem to find the final answer... :/
basicaly i also think it should be CHO like sidbloom said or maybe CHO2 ...

 

[Namehere]

View attachment 38889
EMPERICAL

If you add the percentages 37.5 + 4.17 + 58.3 you get 99.97, so there is a 0.03% missing from somewhere...

 

[sidbloom1995]

the method's right... but cant seem to find the final answer... :/
basicaly i also think it should be CHO like sidbloom said or maybe CHO2 ...

i also used the same procedure!
but since it was asked, i cant help but think that there might be something more to the question??!!
so i want to verify my answer!

 

[Namehere]

View attachment 38889
EMPERICAL

However, if you dont take that into account, you get that the ratio of C: H: O is 1: 1.3344: 1.166
if you times all by 6 so you get integer numbers for all of them -> 6: 8.01: 6.996, which simplifies to 6:8:7
Thus, the empirical formula is C6H8O7, which is correct, since E330 is known for citric acid, which has that formula.

 

[Namehere]

Easy Tip: Never simplify until the last moment!

 

[daredevil]

If you add the percentages 37.5 + 4.17 + 58.3 you get 99.97, so there is a 0.03% missing from somewhere...

oohh ryt... never thought of that....

where did u get this question anyway magnanimous?

 

[DeViL gURl B)]

http://i.imgur.com/G2akAHB.jpg


Try zooming in to see the reactants/conditions. If they're not visible quote me or send me a VM and let me know I'll scan it and reupload. Idk if it's clear enough took a pic from my phone.

Also note of the of arrows is the other way around.. Primary Alcohol -> Aldehyde ->Carboxylic
The Aldyhyde -> Carboxylic arrows are the other way around.

Aldehyde -> Carboxylic reagents are K2Cr2O7 + Acid under reflux
and
Carboxylic -> Aldehyde reagents are LiAlH4 or NaBH4

THANK YOU!!! Soo muchhh!! Well it ain't that clear...so if u don't mind scanning.. It'd be great!
Well I didn't get the aldehyde part...cuz couldn't get the pic properly....
THANK YOU SOO MUCH btw! ^_^

 

[DeViL gURl B)]

Aoa,
And heyy people! Umm I'm lookin for an easy form of PERIODICITY! As most of the papers..have those questions..and in quite a tricky way! So any one who has like...an awesome summary...like the one which won't get outta yr brain...sorta thing! PLEASE SHARE!! Cuz I really sometimes struggle at that part of the paper!
Thank u

 

[sitooon]

Using E0 value ,
Find the products of each compound at Anode ,
AgF
FeSO4
MgBr2

Ans . Oxygen for first two , and Br for MgBr2