Chemistry: Post your doubts here!

[sadiaali]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w03_qp_1.pdf
Please anyone explain me Q27. How is conc sulphuric acid react differently?

 

[syed1995]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w03_qp_1.pdf
Please anyone explain me Q27. How is conc sulphuric acid react differently?

It's simple. The Elimination reaction (Forming of Alkene from Alcohol with the elimination of a an OH and H). That requires OH to be removed from one C and a H to be removed from the neighboring carbon.

the neighboring carbon doesn't have any H attached so there will be no elimination in the case of (CH3)3CCH2OH

 

[syed1995]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_13.pdf
Question 10. Why is the answer A?

The definition of a base is being a proton acceptor. and HSO3- accepts a H+ to form H2SO4.

Look at the other options.. B No.. since SO2 gets oxidized itself it acts as a reducing agent.
C.. it can't be acting as a acid if it is reacting with H+! Acid is an proton donor.
Now D is the confusing choice. see the SO3^2- backwards reaction.. it oxidizes H+ to H2O.. so it acts as a oxidizing agent.

Remember this
Oxidation is Loss of Electrons / Gain of Oxygen / Loss of Hydrogen
Reduction is Gain Of Electrons / Gain of Hydrogen / Loss of Oxygen

An Oxidizing agent itself gets reduced.
An Reducing agent itself gets oxidized.

 

[student1415]

As Salamu Alaikum

can someone plzz help me with q 20 , 29 and 35 http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w03_qp_1.pdf

 

[Abdel Moniem]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w13_qp_13.pdf
Question 3

 

[Abdel Moniem]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w13_qp_13.pdf
Question 26

 

[omarjaved619]

HELP! River water in a chalky agricultural area may contain Ca2+ , Mg 2+, CO3 2–, HCO3–, Cl− and NO3– ions. In a water treatment plant, such water is treated by adding a calculated quantity of calcium hydroxide. What will be precipitated from the river water following the addition of calcium hydroxide?

A CaCl2
B CaCO3
C Ca(NO3)2
D Mg(NO3)2

 

[kitkat <3 :P]

HELP! River water in a chalky agricultural area may contain Ca2+ , Mg 2+, CO3 2–, HCO3–, Cl− and NO3– ions. In a water treatment plant, such water is treated by adding a calculated quantity of calcium hydroxide. What will be precipitated from the river water following the addition of calcium hydroxide?

A CaCl2
B CaCO3
C Ca(NO3)2
D Mg(NO3)2

Is the answer B

 

[omarjaved619]

Is the answer B

Hahaha yes. the "chalky" hints towards carbonate. And its the only one insoluble. Didnt know that CaCl2 is soluble

 

[kitkat <3 :P]

Hahaha yes. the "chalky" hints towards carbonate. And its the only one insoluble. Didnt know that CaCl2 is soluble

Lol

 

[Browny]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w02_qp_1.pdf

Can anyone please explain question 23,36 and 39?
I would be very thankful if anyone can explain.

 

[♣♠ Magnanimous ♣♠]

help me out!! why not B and answer is C. Why?

 

[♣♠ Magnanimous ♣♠]

 

[♣♠ Magnanimous ♣♠]

 

[mehria]

View attachment 43752

isn't it C?

 

[mehria]

View attachment 43749help me out!! why not B and answer is C. Why?

becuz reactivity depends upon bond length not bond energy...

 

[♣♠ Magnanimous ♣♠]

isn't it C?

nope! that's prob. muje bhi C mila

 

[♣♠ Magnanimous ♣♠]

becuz reactivity depends upon bond length not bond energy...

Than why not B

 

[mehria]

nope! that's prob. muje bhi C mila

then wat's the ans?

 

[♣♠ Magnanimous ♣♠]

then wat's the ans?

D