Chemistry: Post your doubts here!

[ZIYAD.beasto]

Need help with chemistry p5 http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s07_qp_5.pdf
QUESTION 2 graph ?

 

[sitooon]

i got the answer but my method is completelyyyyyyyyyyyyyyyyy different from the MS!!
so i dont think i will be able to help you with question 2(c) ~sorry~ T_T
as for the equation i was able to do it, but the next part i was not able to!
you can check the ans. in the pic
i didnt understand the answer of Q5 c(ii)
so can you see if you can help me out with that?!

For question 5c , just you should know when equlibrium shift to right ( Ecell increase )
and when equlibrium shift to left > Ecell decrease !

 

[ZIYAD.beasto]

Hi everyone, AsSalamoAlaikum Wr Wb..

To get things organized in a better way, I am making this thread. As othewise, some queries remain unanswered!

So post your CHEMISTRY doubts in this thread. InshaAllah members around will help you.

Any Chemistry related notes and links will be added here in this post. Feel free to provide the links to your notes around the forum, or any other websites!

Chemistry Notes:


http://www.chemguide.co.uk This is the website, which contains almost everything classified according to the syllabus.

Tips for solving chemistry MCQs 9701/01

Chemistry P5 Tips and Notes

Some links & Notes - by 'destined007'

Chemistry worksheets Link shared by hassam

Chemistry Application Booklet: Mistakes and Corrections!

Calculations for A level Chemistry, author E.N. Ramsden third edition ebook download.


Regards,
XPC Staff.

Need help with chemistry p5 http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s07_qp_5.pdf
QUESTION 2 graph ?

 

[midha.ch]

midha.ch you doing AL CHEMISTRY?

yes! I'm appearing both As and A2 this May

 

[ZaqZainab]

yes! I'm appearing both As and A2 this May

best of luck

 

[midha.ch]

best of luck

Thanks
Do remember me in your prayers so that I get good grades

 

[ZaqZainab]

Thanks
Do remember me in your prayers so that I get good grades

I am just giving As but yeah remember me too

 

[ZIYAD.beasto]

Need help with chemistry p5 http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s07_qp_5.pdf
QUESTION 2 graph ?

 

[sidbloom1995]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_4.pdf
isnt it supposed to be reduction-oxidation ? markscheme says 0.77-1.36 but shouldn't it be 1.36-0.77?

one moere thing i would like to add is that in the MS it said to ignore the sign and the flow is from right to left!!
this means that the Left is (+) and Right is (-), it's just that when they give us a diagram like that they follow there equation of [Ecell = Er - El]
overall this suggest that even when you follow your own logic and understanding on the topic and write it as 1.36 - 0.77 you will get a correct answer for it!
(this part shook me up pretty bad as well, having all my concepts jumbled up once again, but once i calmed down and reconfirmed a few things i was fine )

 

[mahabaloch]

Anyone? need help in NMR

 

[Faaiz Haque]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s05_qp_2.pdf

Part 2d iii, Show calculations with detailed explanations pleaseee
I don't get the Markscheme, thankss

 

[MiniSacBall]

Mass of 1 cm3 of steam (H20) = 1 g
Mol of H20 = 1g / 18 = 0.0555556
1 mol of H20 occupies 24dm^3 at 298K
0.0556 would occupy = 24 x 0.0556 = 1.33 dm^3
Volume of steam at 298K = 1.33 dm^3
Volume of steam at 1 K = 1.33/298 = 0.00446 dm^3
Volume of steam at 596 K = 0.00446 x 596 = 2.668 dm^3 ~ 2.67 dm^3
Answer C.

I swear i would have done this question on my own but this thing drives me crazy!
If i take the temperature in C and not in K. What is the difference. I mean why can't i do like this way:

Mass of 1 cm3 of steam (H20) = 1 g
Mol of H20 = 1g / 18 = 0.0555556
1 mol of H20 occupies 24dm^3 at 25C
0.0556 would occupy = 24 x 0.0556 = 1.33 dm^3
Volume of steam at 25C = 1.33 dm^3
Volume of steam at 1C = 1.33/25 = 0.0532 dm^3
Volume of steam at 323C = 0.0532 x 323 = 17.1836 dm^3 <----------- Why am i getting this thing wrong here! Why!

Any body please help me! Why can't i take C instead of K. I mean are bigger unit soo inaccurate or what?
Also the difference between them is extreme inaccurate!
323C - 25C = 298C = 571K
596K - 298K = 298K = 25C
So basically if you have water at 25 C and you raise the temperature to 323 C. According to Kelvins you have raised only 25C.

For those who are wondering here is the question! [ http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdf ] - Q.6

I am mindfucked here. Or may be i am doing some stupid mistake. I just want you to help me!

Edit: I guess i figured out! These are some special types of unit! they are need added or subtracted to get other unit! So that's why i am having this whole problem.
Hah! Seriously Science. !@#$ Science. This is inaccurate as !@#$. I just can't image how inaccurate science is in this case. This is bullshit! !@#$ science.

So only one question: In exams if i get a question similar to this, i have to take in Kelvins even if the question is in Celsius right?

----------------Totally mind fucked!---------------

 

[sidbloom1995]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s05_qp_2.pdf

Part 2d iii, Show calculations with detailed explanations pleaseee
I don't get the Markscheme, thankss

the answer is simple! the MS just went round about it!!
we already have our equation for H2S with O2

2H2S + 3O2 ---------> 2H2O + 2SO2

we first find the moles of H2S
n of H2S = [8.65/34.1] = 0.254 mol
use the ratio relation from the equation
2 moles of H2S and 3 moles of O2 are uused
H2S : O2
2 : 3
0.254 : x
thus x = (0.254 x 3)/2 = 0.38 mol

now use the formula, volume = moles X 24
V = 0.38 X 24 = 9.12 dm3
thats it

 

[1357911]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_qp_41.pdf
Q-8 cii
Q-3 civ

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_4.pdf
q-10 c

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_qp_43.pdf
Q-7 aiii

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w09_qp_41.pdf
Q7 cii

Can Anyone help me in these questions please?

 

[AbbbbY]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s05_qp_2.pdf

Part 2d iii, Show calculations with detailed explanations pleaseee
I don't get the Markscheme, thankss

H2S + 1.5O2 -> H20 + SO2
8.65/(1+1+32) = 0.254 mols of H2S

1 mol reacts completely with 1.5 mol of O2
0.254 will thus react with 0.254*1.5=0.381 mol of O2.

1 mol of O2 occupies 24dm3
0.381 will occupy 9.15 dm3

ALTERNATE METHOD:

1 mol of H2S = 34g requires 1.5 mol of O2 = 36dm3

so;
34g = 36dm3
8.65g = 9.15dm3

 

[Igcse stuff]

can someone help me with question 1, how do you calculate the number of moles of oxygen atoms for each of the three oxides for part (a)....and i also need help on the other parts as well i.e (b) to (g).... http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w12_qp_51.pdf

I really need your help with question 1

 

[midha.ch]

https://www.xtremepapers.com/community/threads/as-physics-p1-mcqs-yearly-only.17330/
I saw this on the physics doubts thread! Anyone has a similar link for chemistry p1 ??? Would be really thankful if you people hellp me!

 

[papajohn]

I had a question in my head about the chemistry practical of titration. The problem is that i performed the experiment and there is huge fluctuation i.e 19 cm3 and 25 cm3. The teacher told me that it should be correct to 0.1 cm3. The problem is that why there is great difference b/w my result. I think i used only two drops of methy orange or i do not mixed throughly mixed the HCl with distill water.

 

[Faaiz Haque]

the answer is simple! the MS just went round about it!!
we already have our equation for H2S with O2

2H2S + 3O2 ---------> 2H2O + 2SO2

we first find the moles of H2S
n of H2S = [8.65/34.1] = 0.254 mol
use the ratio relation from the equation
2 moles of H2S and 3 moles of O2 are uused
H2S : O2
2 : 3
0.254 : x
thus x = (0.254 x 3)/2 = 0.38 mol

now use the formula, volume = moles X 24
V = 0.38 X 24 = 9.12 dm3
thats it

Omg i'm an idiot, ty!!

 

[sidbloom1995]

Omg i'm an idiot, ty!!

when solving past papers first solve the question and write down your answers and then just compare the final answers and you wont be mislead or confused by the mark scheme!