Chemistry: Post your doubts here!

[Someone2]

Ok so in a Paper 5 , in a planning question, they asked us to mention how we would dry the precipitate. In the Answer scheme, the gave a few methods along with "NOT heat or the use of a Bunsen..."

The next question asked how we would ensure the precipitate was thoroughly dried. The answer went like
"The drying process should be repeated to constant mass . ALLOW HEAT/REHEAT to constant mass/weight."

What is this cwap?

lol i just know that an OVEN is used to dry the precipitate. The constant mass shows that now only the solid is left-all solvent that was adding to the mass is removed.

n yes... paper 5 chem is crap

 

[BeBeskii108]

Yes. Slope is the gradient. You can choose any two points which are sufficiently apart. The construction lines are just a big triangle against the line. Kinda like this https://www.google.com/search?q=find gradient construction lines&client=aff-maxthon-maxthon4&channel=t26&source=lnms&tbm=isch&sa=X&ei=io90U_1Th7S4BPqzgvgG&ved=0CAgQ_AUoAQ&biw=1367&bih=606#facrc=_&imgdii=_&imgrc=q3QY7oC0nNKu_M%3A;5cZQbj0PR8XOYM;http%3A%2F%2Fmathsfirst.massey.ac.nz%2FAlgebra%2FStraightLinesin2D%2Fimages%2Fslope1.gif;http%3A%2F%2Fmathsfirst.massey.ac.nz%2FAlgebra%2FStraightLinesin2D%2FSlope.htm;707;453

Thank you

 

[BeBeskii108]

AAAA I'm worried about my Paper 5. Paper 4 was not easy. So I have to try my best but Paper 5 is difficult.

 

[omarjaved619]

AAAA I'm worried about my Paper 5. Paper 4 was not easy. So I have to try my best but Paper 5 is difficult.

Have faith! All I'll suggest is do as many past papers as you can.

 

[saadgujjar]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s10_qp_52.pdf
q1 c diagram needed

 

[Snowysangel]

Guys post your paper 1 doubts here : https://www.xtremepapers.com/community/threads/chemistry-and-physics-mcqs.33811/

 

[Abdulaziz T]

Guys, I'm really bad in question no.1 experiments in Chem paper 5.. Can anyone give me tips or anything ?

 

[zackle09]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s09_qp_5.pdf

can someone please tell me how to plot the graph for question 2!!

 

[Snowysangel]

Could some one explain. This to me!

 

[YetAnotherCandy]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w13_qp_51.pdf
^^Q1, help needed in calculation, part (d)(iv)

 

[Snowysangel]

Which if the following is the strongest reducing agent?
A Cl-
B Ar
C K+
D Ca 2+
E Al3+
Can someone please answer!! Suchal Riaz GCE As and a level

 

[Suchal Riaz]

Which if the following is the strongest reducing agent?
A Cl-
B Ar
C K+
D Ca 2+
E Al3+
Can someone please answer!! Suchal Riaz GCE As and a level

strongest reducing agent will oxidise most quickly. in all of these ions on Cl- will ask as a reducing agent because:
2Cl(-1) --->CL2 +2e(-)
loss of electron is oxidasation
metal cations will gain electrons so they will reduce
as only Cl will be oxidised it will reduce other so it is strongest among these present options

 

[A star]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_52.pdf
q1 c diagram needed

place a plastic cup stuck on a beaker and place it on a lighted bunsen burner using a tripod stand
thermometers bulb should be half immersed in the solution. temrature range if asked should cover from 30-110 minimum

 

[saadgujjar]

place a plastic cup stuck on a beaker and place it on a lighted bunsen burner using a tripod stand
thermometers bulb should be half immersed in the solution. temrature range if asked should cover from 30-110 minimum

if u don't mind plz draw diagram

 

[Snowysangel]

strongest reducing agent will oxidise most quickly. in all of these ions on Cl- will ask as a reducing agent because:
2Cl(-1) --->CL2 +2e(-)
loss of electron is oxidasation
metal cations will gain electrons so they will reduce
as only Cl will be oxidised it will reduce other so it is strongest among these present options

And what if they had all been atoms? Would it be K, Ca, Al, Cl and Ar in terms of their strength as reducing agents? Basically if their next ionization energy is low they make good reducing agents right?

 

[Snowysangel]

Why are these two mechanisms energy demanding and difficult to carry out:
Converting diamond into graphite
Converting graphite into diamond
Suchal Riaz

 

[Suchal Riaz]

Why are these two mechanisms energy demanding and difficult to carry out:
Converting diamond into graphite
Converting graphite into diamond
Suchal Riaz

is this a past paper question?

 

[Suchal Riaz]

And what if they had all been atoms? Would it be K, Ca, Al, Cl and Ar in terms of their strength as reducing agents? Basically if their next ionization energy is low they make good reducing agents right?

to see which species is good reducing agent see how easily it can oxidise itself.
if it was metal then the metal with most highest ionisation energy would be strongest reducing agent. for example Na can reduce H in H2SO4.

 

[Snowysangel]

to see which species is good reducing agent see how easily it can oxidise itself.
if it was metal then the metal with most highest ionisation energy would be strongest reducing agent. for example Na can reduce H in H2SO4.

Doesnt Na have the lowest ionization energy? How do we know if something makes a good reducing agent, if not by lookibg st their ionization energy?

 

[Suchal Riaz]

Doesnt Na have the lowest ionization energy? How do we know if something makes a good reducing agent, if not by lookibg st their ionization energy?

i told you that a good reducing agent is the one which oxidises most easily. examples:
Cl- Fl- I-
in the above ions the general equation is
2Cl- -->Cl2 + 2e-
Cl- ion is more stable than I- but Fl- is more stable than Cl-. so strongest reducing agent is I-

Cl F I
none of these are reducing agents

Na Mg Al
equation when oxidised
Na --> Na+ + e-
This is the equation of ionisation. Na ionise more readily than Mg which is ionises more readily than Al
So Na is strongest