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Paper 5 Tips !! :)

Boss.Mentalist.Awesome

Boss.Mentalist.Awesome

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In questions where they ask you to write step-by-step description of some experiment and below that questions....Are we supposed to write the whole procedure or just answer the questions??
 
Student12

Student12

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Jiyad Ahsan said:
yaaarrr..... ok umm look at it this way.. say you found that at a certain temperature (say 40 degrees) from your best fit line the solubility of a crystal is 10 (for the heck of explaining !) and so if you have to calculate solubility at 80 degrees you can safely multiply the solubility at 40 degrees by 2.. so your solubility at 80 degrees would be 20
umm its sort of like cross multiplying.. since 10=40, x=80 , find x, so you'd cross multiply)
Click to expand...
Alright :D
 
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backtodev

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Also for June 2012 V1 Q1 c) the planning part
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s12_qp_51.pdf

The ms says
"Check that the solution is made up to the appropriate volume and not that a mass is added to a fixed volume of water."
So the question said "Remember that you are using 100 cm3 of aqueous copper(II) sulfate"
So when making the concentration of the copper sulfate soluton, do I dissolve the CuSo4.5H20 in 100 cm3 water, less than 100 cm3 water, or fill the volumetric flask to 250 cm3.
[p.s. this thread is really amazing, iSA you guys will do brilliantly!]
 
knowitall10

knowitall10

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Boss.Mentalist.Awesome said:
In questions where they ask you to write step-by-step description of some experiment and below that questions....Are we supposed to write the whole procedure or just answer the questions??
Click to expand...
When they say "step by step discription including..." then you explain the whole procedure including the points the question states.
When it says "step by step discrip. by decribing how..." then you only describe the points mentioned.
 
xtremeforums

xtremeforums

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Please answer this, I would be grateful to you! ​
How do we draw the diagram for question 1c?​
​
And can someone please explain how to make the molal solutions for part 1d?​
Instead of dissolving different masses in (the same volume of) water, can we prepare a 1 molal solution, by dissolving 7.46g of the chloride in 100g of water. Then carry out serial dilutions of the 1 molal solution to prepare 0.8, 0.6, 0.4 etc etc molal solutions? ​
This method is not mentioned in the mark scheme though..​
​
THANKYOU :) ​
 
X

xhizors

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rafay malik said:
xhizors.
I wanted to confirm the method for determining solubility of a substance.
Can we take different masses of the substance In a fixed volume of water (let's say 100cm3) , and stir the solution at a fixed temperature until no more dissolves. Then allow the solution to cool while stirring and note the temperature at which the first crystals appear.
Click to expand...
yup similarly u can evaporate the water to get the residue(mass of crystals)
 
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MaxStudentALevel

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Hey guys just a couple more questions I'd be so grateful if you answered
knowitall10 got my spelling of grateful right! ;)

-ON 2007 Q1 moles 0.05-0.25 specified why do they do that?
-ON 2009/52 Q1 (a) the MS says "predicts all strong acids have constant DeltaHNeut. <--- HOW?
And the same question says "no grading here"
-ON 2009/52 Q1 (d) I get that 6*10^-2 moles is excess but how do we fill the table?

Any help would be greatly appreciated guys!
 
Jafar Sadek

Jafar Sadek

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xhizors O/N 10 PAPER 53... question 1 c.... the mark scheme says that "Reaction vessel seperated" or "Small tube for catalyst" .... can some1 please explain this part....or post a screenshot of the diagram.. thank you..
 
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MaxStudentALevel

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backtodev said:
Can someone please take a picture of their graph in June 2009 P5 Q2 [the solubility question]
I've done it, but I'd just like to make sure that it's actually right
Also can anyone tell me what their transition temperature was? Q2 c)
http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s09_qp_5.pdf
Click to expand...


Mine was 67.5, same as someone else in the main chemistry doubt thread that posted their graph! You should try and go find it! It's after page 220!
 
Soldier313

Soldier313

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MaxStudentALevel said:
Hey guys just a couple more questions I'd be so grateful if you answered
knowitall10 got my spelling of grateful right! ;)

-ON 2007 Q1 moles 0.05-0.25 specified why do they do that?
-ON 2009/52 Q1 (a) the MS says "predicts all strong acids have constant DeltaHNeut. <--- HOW?
And the same question says "no grading here"
-ON 2009/52 Q1 (d) I get that 6*10^-2 moles is excess but how do we fill the table?

Any help would be greatly appreciated guys!
Click to expand...
- qn 1, i haven't seen the paper
- the p52 qn, it's because strong acids dissociate 100%, and The enthalpy change of neutralisation is the enthalpy change when 1 mol of water, H2O, is formed in the neutralisation of an acid and base.

Since all strong acids fully dissociate, they all produce 1 mol of water, hence they all have a constant mass, made sense? :)
-while filling in the table for your third question, just ensure that for all the monobasic acid ie HCl and HNO3, when you calculate the moles, you get something less than 0.06
while doing it for the dibasic acids, just ensure that your moles are half of your moles for the dibasic acid
AND ensure that for ALL the acids volume is constant

so for eg, i settle on 0.04 moles since it's less than 0.06, for the monobasic acids
i can have something like 40cm3 volume and 1 moldm-3 concentration, (to prove just calculate the moles of this soln, you get 0.04)
for the dibasic acids, i need the same volume so 40 cm3 but the moles have to be half, so 0.02 moles, calc the concentration, you get 0.5! :)

knowitall10 here you can read what i've written for the 3rd part :)
 
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