Chemistry: Post your doubts here!

[donewithtime80]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s03_qp_4.pdf

Q 1, b (i) please...

http://studyguide.pk/Past Papers/CI.../9701 - Chemistry/9701_s03_ms_1+2+3+4+5+6.pdf

 

[The Sarcastic Retard]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s03_qp_4.pdf

Q 1, b (i) please...

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9701 - Chemistry/9701_s03_ms_1+2+3+4+5+6.pdf

Ecell = 0.76V
Electrode potential of (Cu2+/Cu) = 0.34V
Electrode potential of (M2+/M) = ?

There is one rule to find Ecell. Always subtract big value from small. Here we know the big value is of Cu2+/Cu as its mentioned to be positive electrode. Hence,
ECu - EM = Ecell
0.34 - Em = 0.76
Em = -0.42V

 

[The Sarcastic Retard]

The correct answer here is B. Some one explain why View attachment 58111

I always used trial and error method for this kindda questions.
For option B:~

Sum of moles at equilibrium = 2 - 2x + 2x + x = 2 + x

 

[Saad the Paki]

I always used trial and error method for this kindda questions.
For option B:~
View attachment 58116
Sum of moles at equilibrium = 2 - 2x + 2x + x = 2 + x

Niice thanks !

 

[The Sarcastic Retard]

25 a and b
I guess I know the answer, but I am not sure if I am 100% correct.
a) From all three Cr2+ has least positive E(std) value. Hence it needs the strongest reducing agent (more -ve E(std) value agent) to reduce it.
b) From all three Ag has most posivtive E(std) value. Hence it needs the strongest oxidising agent (more +ve E(std) value agent) to oxidise it.
M I corrct? If not then do correct me. Thanks.
Metanoia
DarkEclipse
Dark Destination
awesomaholic101
FranticAmaze
My Name

 

[MYLORD]

I have notes for chemistry unit 3 and physics unit 3, you are doing edexcel IAL correct? If so, just give me your email so i can send you the files

can u kindly give me any notes u have for physics and chemistry ial notes ASAP
Whatever notes u have

 

[My Name]

View attachment 58131
25 a and b
I guess I know the answer, but I am not sure if I am 100% correct.
a) From all three Cr2+ has least positive E(std) value. Hence it needs the strongest reducing agent (more -ve E(std) value agent) to reduce it.
b) From all three Ag has most posivtive E(std) value. Hence it needs the strongest oxidising agent (more +ve E(std) value agent) to oxidise it.
M I corrct? If not then do correct me. Thanks.
Metanoia
DarkEclipse
Dark Destination
awesomaholic101
FranticAmaze
My Name

Didn't get the tag.
I think you're answers are right.
Doesn't the book have answers at the back?
awesomaholic101 FranticAmaze Midnight dream Lola_sweet What do you say?

 

[awesomaholic101]

Didn't get the tag.
I think you're answers are right.
Doesn't the book have answers at the back?
awesomaholic101 FranticAmaze Midnight dream Lola_sweet What do you say?

Those answers better be right .. Coz I would say that too and I don't want to be wrong

 

[Metanoia]

View attachment 58131
25 a and b
I guess I know the answer, but I am not sure if I am 100% correct.
a) From all three Cr2+ has least positive E(std) value. Hence it needs the strongest reducing agent (more -ve E(std) value agent) to reduce it.
b) From all three Ag has most posivtive E(std) value. Hence it needs the strongest oxidising agent (more +ve E(std) value agent) to oxidise it.
M I corrct? If not then do correct me. Thanks.
Metanoia
DarkEclipse
Dark Destination
awesomaholic101
FranticAmaze
My Name

Yes. That is correct. You can also use O level chemistry to check your answer- in decreasing reactivity of metals, Chromium, Iron and Silver.

So the most stable ion is Cr2+ and the most stable metal is Ag.

They will require the strongest reducing agent and oxidizing agent respectively to under changes.

 

[nehaoscar]

Anyone with the new 2016 coursebook, please can you tell me if High-performance liquid chromatography (HPLC) is given in the text book??
It's not in the syllabus so do I need it??

 

[The Sarcastic Retard]

Yes. That is correct. You can also use O level chemistry to check your answer- in decreasing reactivity of metals, Chromium, Iron and Silver.

So the most stable ion is Cr2+ and the most stable metal is Ag.

They will require the strongest reducing agent and oxidizing agent respectively to under changes.

THanks....

 

[Saad the Paki]

Q3. Help please. The answer is B.

 

[Metanoia]

Q3. Help please. The answer is B. View attachment 58386

Eqn 1 is reduction.
Eqn 2 is oxidation.

You need to make sure the number of electrons are the same before combining or comparing.

Therefore you need to multiply eqn 2 throughout by 2.

 

[HumptyR]

Let the Q1 be solved.

 

[nehaoscar]

Find AS organic chemistry reagents chart here:
https://www.xtremepapers.com/commun...c-chemistry-reagents-chart.42668/#post-949384

 

[HumptyR]

 

[holoholo]

When concentrated nitric acid, HNO3, is added to copper turnings, a brown gas is evolved. Use data from the Data Booklet to construct an ionic equation for this reaction.
which equation of copper should i use and why ?

 

[HumptyR]

When concentrated nitric acid, HNO3, is added to copper turnings, a brown gas is evolved. Use data from the Data Booklet to construct an ionic equation for this reaction.
which equation of copper should i use and why ?

Well you should use this eq. :Cu + 4H+ + 2NO3– → Cu2+ + 2NO2 + 2H2O. Because it is ionic :3

 

[holoholo]

why can't we use Cu+ instead of Cu2+ ?

 

[HumptyR]

why can't we use Cu+ instead of Cu2+ ?

Well, IDK :3 But i guess we can't use Cu+ simply because NO2 and H2O need e- :3