Biology; Chemistry; Physics: Post your doubts here!

[ciesgetoveralready]

http://papers.xtremepapers.com/CIE/...l O Level/Chemistry (5070)/5070_w12_qp_41.pdf
Q8 part e?

 

[FLRNAB]

they say in excess to equal masses. Though CaCO3 was in excess but the amount was same in all three experiments.

Read the question again.
In experiment 1 the number of moles of acid was less than in experiment 2 <-- This is wrong.
They asked for the right one.

 

[ciesgetoveralready]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w12_qp_41.pdf
Q8 part e?

Anyone pleaseeeeeeee?

 

[FLRNAB]

Anyone pleaseeeeeeee?

Wrong paper?

 

[ciesgetoveralready]

Wrong paper?

Q9 sorry

 

[funky brat]

Anyone pleaseeeeeeee?

Question 8 ka e part kahan hai?

 

[funky brat]

Anyone pleaseeeeeeee?

26.4 cm^3 contains 0.0025 moles so 24000cm^ 3 would contain x moles.
2.27 moles.

 

[ciesgetoveralready]

A

26.4 cm^3 contains 0.0025 moles so 24000cm^ 3 would contain x moles.
2.27 moles.

Answer is 0.0947

 

[Uchiha-Sasuke]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w12_qp_41.pdf
Q9 part e?

26.4cm^3 (this is the average volume calculated) --->0.0025 MOLES
1000cm^3 -----> 0.0025/26.4*1000 = 0.0947 MOLES
edited .. these were moles

Explain plssssss
.View attachment 42225

***amd*** Awesome12

just where did you get that questions :O
I think it's CuO
1.CuO is black
2.CuO+ HCL---> H2O + CuCl2
the above solution was heated so CuCl2---> Cu + Cl2 (chlorine bleaches)
3. CuO + H2O2 ---> Cu + H2O + O2 (relights)

 

[funky brat]

26.4cm^3 (this is the average volume calculated) --->0.0025cm^3
1000cm^3 -----> 0.0025/26.4*1000 = 0.0o947


just where did you get that questions :O
I think it's CuO
1.CuO is black
2.CuO+ HCL---> H2O + CuCl2
the above solution was heated so CuCl2---> Cu + Cl2 (chlorine bleaches)
3. CuO + H2O2 ---> Cu + H2O + O2 (relights)

Isn't 1 dm^3 equal to 24000 cm^3?

 

[FLRNAB]

Isn't 1 dm^3 equal to 24000 cm^3?

For Gases 24dm = 24000cm
1 mole occupies 24 dm.

 

[FLRNAB]

Explain please.
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w09_qp_4.pdf question 6.
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s11_qp_42.pdf question 6.
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s09_qp_4.pdf question 4.

Experiment P:
5 cm,
0.20 mol/dm --> More Concentration
Zinc Pieces --> Less Surface Area

Experiment Q:
20 cm,
0.10 mol/dm --> Less Concentration
zinc powder --> More surface Area

Moles in P = 0.001 --> Less Volume of Gas
Moles in Q = 0.002 --> More Volume of Gas

Why P has higher rate of reaction?
Imagine a crushing machine (High conc) crushing a stone (Low SA) vs breaking 100 stones (High SA) using a hammer(Low conc).

 

[Hamza_Akmal]

noo iron 3 sulphate is yellow actually
what I am worried is we have learnt iron 3 compounds to be red
so I was saying how is it yellow

The answer is colourless to purple because the solution is VERY dilute

 

[Laibaaa]

I haven't done organic chemistry properly esp macromolecues what should i study from them? Its hard remembering all the names and structures. Help please :|

 

[Hamza_Akmal]

I haven't done organic chemistry properly esp macromolecues what should i study from them? Its hard remembering all the names and structures. Help please :|

Just remember the trends in properties of the different groups and learn how to find molecular formulas of the compounds. Organic is thoroughly tested in p2, not in p4

 

[Laibaaa]

Just remember the trends in properties of the different groups and learn how to find molecular formulas of the compounds. Organic is thoroughly tested in p2, not in p4

Thank you and what about Macromolecules? :|

 

[exploded diper]

http://papers.xtremepapers.com/CIE/...l O Level/Chemistry (5070)/5070_s11_qp_42.pdf
q) 6....zinc is in peices and zinc is in powder...still the other reaction with peices is faster....
when metals are deposited on cathode will they always form a sludge.....
do we have to write gas syring or syringe.....<----- i know a sillly question
vats the use of proclein chips in cracking.......

 

[FLRNAB]

http://papers.xtremepapers.com/CIE/...l O Level/Chemistry (5070)/5070_s11_qp_42.pdf
q) 6....zinc is in peices and zinc is in powder...still the other reaction with peices is faster....
when metals are deposited on cathode will they always form a sludge.....
do we have to write gas syring or syringe.....<----- i know a sillly question
vats the use of proclein chips in cracking.......

Experiment P:
5 cm,
0.20 mol/dm --> More Concentration
Zinc Pieces --> Less Surface Area

Experiment Q:
20 cm,
0.10 mol/dm --> Less Concentration
zinc powder --> More surface Area

Moles in P = 0.001 --> Less Volume of Gas
Moles in Q = 0.002 --> More Volume of Gas

Why P has higher rate of reaction?
Imagine a crushing machine (High conc) crushing a stone (Low SA) vs breaking 100 stones (High SA) using a hammer(Low conc).

They accept both syringe and gas syringe.

 

[exploded diper]

I haven't done organic chemistry properly esp macromolecues what should i study from them? Its hard remembering all the names and structures. Help please :|

study the general properties,....and all the formulas...and the way to make each polymer.......i guess.....just do read the whole chapter atleast once....

 

[funky brat]

http://papers.xtremepapers.com/CIE/...l O Level/Chemistry (5070)/5070_s11_qp_42.pdf
q) 6....zinc is in peices and zinc is in powder...still the other reaction with peices is faster....
when metals are deposited on cathode will they always form a sludge.....
do we have to write gas syring or syringe.....<----- i know a sillly question
vats the use of proclein chips in cracking.......

Porcelain acts as a catalyst.
Write gas syringe.
The question is explained a few posts back.
Yeah they are deposited in molten form.