Chemistry: Post your doubts here!

[MaxStudentALevel]

Biochemistry is all about glycolysis We studied that in bio...no shitty chem involved

Hahahahhaaa true!
Not just glycolysis though! Lol

 

[iKhaled]

Chem is not in medicine

the fact that CHEMISTRY = MEDICINE

 

[1357913579]

the fact that CHEMISTRY = MEDICINE

i think we have physics exam as well??

 

[knowitall10]

the fact that CHEMISTRY = MEDICINE

yeah but not this weirdo chem isn't there..it's the simple chem like peptides and polypeptides..

 

[Warrior66]

Asalam-o-Alaikum!
Can anyone please explain how to do 1 f. in this paper http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w06_qp_3.pdf?
I have the values for the previous sections:
On page two, 'volume of FA 1 run into the flask / cm3' my value was 34.4 cm3
then at the bottom of page two, volume of FA5 that reacted with 25.0 cm^3 was 34.85cm^3
and I calculated e) which is 0.098 mol dm^3
so using these values could you please explain how to do the f part?
Thanks a bunch!

 

[Student12]

Chem is not in medicine

What all subjects have you given for medicine?

 

[ahmed abdulla]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s04_qp_1.pdf
q 8 and 28 plz ?

 

[iKhaled]

for question 8 u need to do a hess cycle diagram which will look like this....

the values of 590 and 1150 are the first and second ionisation energies!

for question 28 the answer is B because if u can see when we write skeletal formulas we dont include the hydrogen attached on the carbon. the only one that has that is B!

 

[knowitall10]

Who's still discussing chemistry iKhaled ?

 

[iKhaled]

Who's still discussing chemistry iKhaled ?

i still have paper one on the way!

 

[Fatum Zuh]

Help me pls!
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s03_qp_3.pdf
Question 3[ii], [c] and [d][ii][iii]
Thanks

 

[iKhaled]

Help me pls!
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s03_qp_3.pdf
Question 3[ii], [c] and [d][ii][iii]
Thanks

lol??? IGCSE paper in this thread go to the IGCSE forums dude

 

[strangerss]

HEY can some one please check if the answer in the marking scheme in paper May/June 2011 33 for question c is correct , from where they brought the 10 to multiply? can some one pleasee help?

 

[hela]

where can I find old past papers MCQ PAPER 1

 

[hela]

how to get old past papers for chemistry AS AND A LEVEL

 

[Warrior66]

HEY can some one please check if the answer in the marking scheme in paper May/June 2011 33 for question c is correct , from where they brought the 10 to multiply? can some one pleasee help?

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s11_qp_33.pdf
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s11_ms_33.pdf
I guess you're talking about 1 c part iii, you have to multiply the answer you got in part ii with 10 because if 25 cm3 of Fa1 have the amount of moles you found out for ii, then 250 cm3 of FA1 has 10 times as much amount of moles..
see, i think you're confused because you probably think that the II mark on the mark scheme is for part ii. But it's not. It is one whole mark consisting of what calculation you did in part ii and iii.
Then for iv you multiply the Mr of FA1 with the moles from iii and then divide it by the mass of FA1 you found in 1a. 'weighing out the salt' part and times it with 100.

 

[Umar Zain]

For question 1. (e)(ii) [36/ON/2010]... i don't understand why "Puts acid/FB 3 in burette and pipettes NaOH/ FB 2
into flask" can overcome the problem

 

[h4rriet]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf
Question 10
How do I know the bond angles in these options and how to find the answer!? I'm clueless.

Angles between 109 and 110 are for tetrahedral molecules with 4 bonds. SiO2 has a tetrahedral structure, that's known; so does propane. If you draw the structure of ethanoic acid, you'll see that one C is attached to 4 other groups, therefore the bond angle for it must be 109.5. That leaves graphite.

 

[h4rriet]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s04_qp_1.pdf
q 8 and 28 plz ?

8. You must draw a Hess cycle for this:

590 is the first ionisation energy, and 1150 is the second.
28. You first draw the structural formula of the monomer, then the skeletal:

 

[Islam Atef]

guys please I need june and november 2002 markscheme for paper 1