Chemistry: Post your doubts here!

[..sacrifice4Revenge..]

20 NH3 + 10 SO2 = 20 NO + 10 S + 3 H20 this is what google took me too

How many pprs did u do?!

 

[ZaqZainab]

How many pprs did u do?!

13 to be exact and you?

 

[Metanoia]

20 NH3 + 10 SO2 = 20 NO + 10 S + 3 H20 this is what google took me too

Its unlikely you will be expected to create this equation on your own without sufficient information.

Linking to the syllabus, we more or less apply the concept of acid (SO2) + base (NH3) --> salt

 

[MaboroshI_I]

This question please! :'(

 

[..sacrifice4Revenge..]

13 to be exact and you?

2008-june 2013

 

[princessnoor]

r

Yes, two with methanoic acid, one with ethanoic and one with propanoic. So total are 4.

ryt!

 

[GCE As and a level]

Ok, guys. Its past midnight for me.

Time for me to log off.

If things go well, I might be back for the November batch, perhaps some of you might be kind enough to help them also since you have already ploughed through the questions in your current preparations.

All the best for your papers and your soon-to-be achieved freedom from exams.

Sir,I appreciate your help to all of us
THANKS

 

[Metanoia]

This question please! :'(

my last question, but will work out step by step with your input.

Can you work out,

moles of Ti+ : mole of VO3+ ?

 

[maestro maisam]

Guys how many marks are you guys getting on average in Chem Paper 1 --- I get around 30... So Damn Scared!!

 

[DeViL gURl B)]

Oct/ nov 2008
PLEASE HELP!!
Question 2 ans is C
4 answer is C
I don't understand 3 :$ answer is D
30 !! Answer is C

Please HELPPPP!!!

 

[maestro maisam]

Guys how many marks are you guys getting on average in Chem Paper 1 --- I get around 30... So Damn Scared!!

 

[princessnoor]

In Kc we do not take the concentration of the solid. So in this case we will not include the concentration of Ag(s)
So it will be as follows:
Kc= (0.56) / (0.44^2)
= 2.89
That's option D

need help in this question
Q: flask X contain 1 dm3 of helium at 2kpa pressure and flask Y contain 2 dm3 of neon at 1kpa pressure.
if the flasks are connected at constant temperature, what is the final pressure?
A: 4/3 kpa
B:3/2 kpa
C; 5/3 kpa
D:2 kpa
how do we solve it and answer is A

 

[ZaqZainab]

need help in this question
Q: flask X contain 1 dm3 of helium at 2kpa pressure and flask Y contain 2 dm3 of neon at 1kpa pressure.
if the flasks are connected at constant temperature, what is the final pressure?
A: 4/3 kpa
B:3/2 kpa
C; 5/3 kpa
D:2 kpa
how do we solve it and answer is A

according to boyle's law, p1v1 = p2v2
so when the 2 flask connect together, the total volume is now 1 + 2 = 3dm3
using the formula above , for flask X
- 1 x 2 = p x 3
- p = 2/3
for flask Y
- 2 x 1 = p x 3
- p = 2/3
therefore, the total pressure after both flask connect is 2/3 + 2/3 = 4/ 3
so answer is A.

 

[MaboroshI_I]

my last question, but will work out step by step with your input.

Can you work out,

moles of Ti+ : mole of VO3+ ?

That'll be 3:2

 

[Snowysangel]

qhttp://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_s13_qp_13.pdf 8

 

[sweet.sugar]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s09_qp_1.pdf
Q1-D and q3-C
Plz help

 

[Snowysangel]

yes i made a mistake. it had to be x²

Metanoia http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s13_qp_13.pdf q8 the ans is D

 

[Metanoia]

That'll be 3:2

From half equation,
Tl+ --> Tl3+ + 2e

So 3 moles of Ti+ loses 6 moles of electrons to 2 moles of VO3+

1 mole of VO3+ gains 3 moles of electrons (oxidation state will decrease by 3 units)

V in VO3+ has original oxidation number of +5.

New oxidation number = +5 - 3 = +2

 

[MaboroshI_I]

From half equation,
Tl+ --> Tl3+ + 2e

So 3 moles of Ti+ loses 6 moles of electrons to 2 moles of VO3+

1 mole of VO3+ gains 3 moles of electrons (oxidation state will decrease by 3 units)

V in VO3+ has original oxidation number of +5.

New oxidation number = +5 - 3 = +2

Got it! Thank you so much!

 

[Metanoia]

Metanoia http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s13_qp_13.pdf q8 the ans is D

D is lowest among all as its P.D-P.D, the rest is hydrogen bonding.