Biology; Chemistry; Physics: Post your doubts here!

[Mahnoorfatima]

http://papers.xtremepapers.com/CIE/...l O Level/Chemistry (5070)/5070_s11_qp_42.pdf
QUESTION 8 Part I. The last part, anyone?

 

[Mahnoorfatima]

http://papers.xtremepapers.com/CIE/...l O Level/Chemistry (5070)/5070_w11_qp_42.pdf
Question 8 b part iii

 

[asadalam]

In 2,b,ii) how are we supposed to know that iodine is preferentially discharged?Isnt the only one chlorine in our syllabus that can be discharged in stead of oxygen??

 

[FLRNAB]

In 2,b,ii) how are we supposed to know that iodine is preferentially discharged?Isnt the only one chlorine in our syllabus that can be discharged in stead of oxygen??

Ion with more concentration will get discharged. Simple rule. Applies to Cations and Anions. But our teacher told us only Cl,Br,I.

 

[Mahnoorfatima]

Anyone answer my questions as well. -_- Ive been waiting since decades.

 

[FLRNAB]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w11_qp_42.pdf
Question 8 b part iii

Q8 A

 

[Mahnoorfatima]

Q8 A

Oh LOL! I posted the wrong question. -_-
I was asking about the last part of the paper the concentration of sodium thiosulfate in the 1st expt.

 

[Qasim Hafeez]

Guys please tell how to solve these type of question.

26. An aqueous solution of compound X reacts with aqueous sodium hydroxide to form a green precipitate and then aluminium powder is added. The mixture is heated a gas that turns damp red limtus paper blue is given off?
What is X?

A. ammonium nitrate
B. copper (II) cholride
C. iron(II) nitrate
D. iron (III) cholride

 

[DaniyalK]

Guys please tell how to solve these type of question.

26. An aqueous solution of compound X reacts with aqueous sodium hydroxide to form a green precipitate and then aluminium powder is added. The mixture is heated a gas that turns damp red limtus paper blue is given off?
What is X?

A. ammonium nitrate
B. copper (II) cholride
C. iron(II) nitrate
D. iron (III) cholride

First one is test for Fe+2 ion and the second is test for nitrate ion. So you join the 2 together and answer is C.

 

[Qasim Hafeez]

First one is test for Fe+2 ion and the second is test for nitrate ion. So you join the 2 together and answer is C.

I know the answer, i checked it. But how do we get it?

 

[FLRNAB]

I know the answer, i checked it. But how do we get it?

Page 29, Qualitative Analysis Notes:
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_y14_sy.pdf

 

[Qasim Hafeez]

Page 29, Qualitative Analysis Notes:
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_y14_sy.pdf

But it was a part of MCQs paper?

 

[Qasim Hafeez]

And are these all the tests that should be learned? or any more?

 

[FLRNAB]

But it was a part of MCQs paper?

And are these all the tests that should be learned? or any more?

These tests only. CIE says you must know these by heart for Paper 1,2,4

 

[Qasim Hafeez]

These tests only. CIE says you must know these by heart for Paper 1,2,4

Thank you very much for you help. And is desalination still a part of new syllabus?

 

[Mahnoorfatima]

Can we write that the blue solution fades in the observations for the reaction b/w Zn and copper II sulfate ?

 

[Fate0]

Can we write that the blue solution fades in the observations for the reaction b/w Zn and copper II sulfate ?

Yes you can.

 

[asadalam]

Can we write that the blue solution fades in the observations for the reaction b/w Zn and copper II sulfate ?

This is an oft-repeated q and its observations include:
Zinc completely dissolving
Pink solid deposited(copper)
Blue color of solution fades

 

[asadalam]

Q4.

 

[Mahnoorfatima]

Q4.[/quot
Calculate the moles of sodium hydroxide and then in each part see which one equals to the moles of Naoh