Chemistry: Post your doubts here!

[MaxStudentALevel]

Hey I've got a question about this chem p5 you guys are talking about above ^
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s11_qp_52.pdf
So for Q2 a) how did you calculate the solubility column?
Like was it just (mass of water) divided by (mass of solid) or something else?
Help would be greatly appreciated

I did as below:
-1 column mass of solid (D-C) in g
-2nd column mass of water (C-B) in g
-3rd column solubility per 100g (E*100) /F

The last parts logic Is as follows:
-Since solubility is to be given in g of solid per 100g of water,
You divide 100 by the mass of water and that given you how much times the solid will be in 100g!

 

[xhizors]

Hey I've got a question about this chem p5 you guys are talking about above ^
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_qp_52.pdf
So for Q2 a) how did you calculate the solubility column?
Like was it just (mass of water) divided by (mass of solid) or something else?
Help would be greatly appreciated

yup to MaxStudent
(E) mass solid---(Dissolves in)----> (F) gram of Water
so X g of solid -------> 100 gram of water!!
by unitry u get the same formula as stated above!!
Solubility = (mass of solid x 100)/mass of water

 

[xhizors]

Do we always look at the Y axis?

its easy to think by that way!

 

[xhizors]

Post Your doubts Chem P5er's !!

 

[strangerss]

if a hydroxyl group is in a ketone or aldehyde they have the name hydroxy for example 2-hyrdoxybutanal or 2-hyroxybutanone

THANKS A LOT

 

[strangerss]

WHICH TYPE OF INTERMolecular forces is the weakest? coz in my book its van der waals where was i my chemistry guide its permanent dipole?

 

[salvatore]

WHICH TYPE OF INTERMolecular forces is the weakest? coz in my book its van der waals where was i my chemistry guide its permanent dipole?

van der Waal's forces are the weakest because they are just induced dipoles..

 

[Soldier313]

Aoa wr wb

Can someone please help me with the diagram in qn 1 of this paper?
and qn 2, could someone please tell me what values they get for solubility?
(i used the same method indicated above by xhizors and MaxStudentALevel

......but on plotting the points i get a curve with 5 anomalies! )

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_qp_52.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_ms_52.pdf

Thanx a lot
JazakAllah khair

 

[xhizors]

Aoa wr wb

Can someone please help me with the diagram in qn 1 of this paper?
and qn 2, could someone please tell me what values they get for solubility?
(i used the same method indicated above by xhizors and MaxStudentALevel

......but on plotting the points i get a curve with 5 anomalies! )

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_qp_52.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_ms_52.pdf

Thanx a lot
JazakAllah khair

for plotting
yeah exactly they are not anamolies, it is curve draw a line connecting the points !

 

[MaxStudentALevel]

for plotting
yeah exactly they are not anamolies, it is curve draw a line connecting the points !

I had the same confusion!!! It's a curve!

 

[MaxStudentALevel]

its easy to think by that way!

Yes but the errors don't always involve the Y axis!

 

[MaxStudentALevel]

COULD SOMEONE MAKE A SEPARATE P5 THREAD? FOR CHEM?

 

[xhizors]

Yes but the errors don't always involve the Y axis!

No they do involve the Y-axis only
as Y-axis in independent axis
so take an eg
u collecting volume of CO2 from CuCarbonate
on x-axis Cu(CO3)2 mass
on Y-axis volume of CO2
agar u take less mass of Cu(CO3)2 u definately get less amount of CO2
but less CO2 collected than expected can be caused by many reasons like bung placed lately or timed less etc etc!!
hope that helps !

 

[MaxStudentALevel]

No they do involve the Y-axis only
as Y-axis in independent axis
so take an eg
u collecting volume of CO2 from CuCarbonate
on x-axis Cu(CO3)2 mass
on Y-axis volume of CO2
agar u take less mass of Cu(CO3)2 u definately get less amount of CO2
but less CO2 collected than expected can be caused by many reasons like bung placed lately or timed less etc etc!!
hope that helps !

It does make sense! But sometimes it says like reading taken at too high a temp (as ind) and the error would be due to not letting apparatus cool down ?

 

[Namera]

Lithium is an alkali metal – one of a group of very reactive metals which are stored under oil to prevent contact with air and water vapour.
The reaction of lithium with water can be represented by the equation below.
2Li(s) + 2H2O(l) → 2LiOH(aq) + H2(g)
(a) In the space below, draw a diagram that clearly shows the apparatus you could use to:
q react a weighed amount of lithium metal with water, q collect the hydrogen gas produced,
q measure the volume of gas produced.

Plz help!

 

[Namera]

Lithium is an alkali metal – one of a group of very reactive metals which are stored under oil to prevent contact with air and water vapour.
The reaction of lithium with water can be represented by the equation below.
2Li(s) + 2H2O(l) → 2LiOH(aq) + H2(g)
(a) In the space below, draw a diagram that clearly shows the apparatus you could use to:
- react a weighed amount of lithium metal with water,

collect the hydrogen gas produced,

measure the volume of gas produced.

Plz help!

Li is so reactive. We cannot possibly add water directly

 

[TSZ]

Hey, I have some P5 problems.
my first question is from May june 12 ppr 51. In Q1 part (c), can any one explain, in detail (as these questions always get the best of me), how to produce a saturated solution of concentration 1.39 moldm-3. Then I can handle the rest
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s12_qp_51.pdf
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s12_ms_51.pdf

My next problem is in Paper 51 of Nov 12. What I don't get is that in Q1 part (e), how will we use the results to reach a conclusion. The mark scheme says to calculate moles of Pb and O, but in metallic reduction by H2, i think water is produced and not O2, then how will we calculate moles of Oxygen. Thank you in advance

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w12_qp_51.pdf
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w12_ms_51.pdf

 

[bravegirl123]

I need help in MCQ# 11 and 33 of this paper: http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s11_qp_12.pdf

 

[knowitall10]

By the way... i was just thinking that i think many of us did numerous Paper 5's.. don't you think we must start paper4 cuz there arent many days left to revise it.. Paper 5 doesnt really affect much of the overall grade. don't you think?

 

[applepie1996]

By the way... i was just thinking that i think many of us did numerous Paper 5's.. don't you think we must start paper4 cuz there arent many days left to revise it.. Paper 5 doesnt really affect much of the overall grade. don't you think?

HA HA xD
everything helps ............whether its paper 5 or 4
besides its fine you can start practicing paper 4 after paper 5
you have a lot of time after that
in the end its your choice