• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Chemistry: Post your doubts here!

Messages
13
Reaction score
1
Points
13
How was it......to me it was pretty much tooo easy

Hey I did the same one!

I got the first question completely wrong since i didn't get the correct values for x and y, but do you think they will give error carried forawerd marks in the following ones? Because I didn't use the x=4 and y=10 since I thought I had the values correct. I got 6 and 16, which make nl sense!

For the one on lattices and all that, what type of lattice is ice? And the bonding between iodine?
 
Messages
112
Reaction score
24
Points
28
Hey I did the same one!

I got the first question completely wrong since i didn't get the correct values for x and y, but do you think they will give error carried forawerd marks in the following ones? Because I didn't use the x=4 and y=10 since I thought I had the values correct. I got 6 and 16, which make nl sense!

For the one on lattices and all that, what type of lattice is ice? And the bonding between iodine?
i they will probably give u ecf marks . the values i got were x=3 and y=8 .Double your answers haha and as for lattice for ice i wrote crystal and bonding for ice covalent
 
Messages
97
Reaction score
11
Points
18
It was pretty calm. I was so glad Enthalpy didnt come, Organic was soo calm. I am sure paper 4 is gonna be deadly. All the best guys!!
 
Messages
5
Reaction score
0
Points
11
Could someone please help with a calculation from Paper 3 (may/june_2009). Its the calculations portion of question #1. Ive attached my work. The question is a titration of borax vs HCl.
  • I am having difficulty understanding where the .008moles HCl come from on the mark scheme on #1c(i).
  • I am having difficulty understanding why the Mr is so large from my calculations on #1c(iv)
thanks!!
 

Attachments

  • may_june_2016_34.pdf
    101.1 KB · Views: 6
Messages
132
Reaction score
46
Points
38
Guys O/N 2015 P52 q2b part ii, please help. How do I draw the 2 best fit lines and MS even says something about horizontal line???
 
Messages
176
Reaction score
186
Points
53
how to do Question 1 ,part d (i)
Moles of Iodine in the original solution= 0.2*50/1000=1x10-2
Moles of Iodine in the 10cm3 portion=1x10-2*(10/100)=1x10-3

The ratio of iodine:thiosulfate is 1:2
Therefore number of moles of thiosulfate= 1x10-3*2=2x10-3

Volume of 0.1 mol/dm3 thiosulfate= (2x10-3/0.1)*1000 (From the formula, volume=(moles*1000)/concentration)
Answer is 20 cm3
 
Messages
176
Reaction score
186
Points
53
Guys O/N 2015 P52 q2b part ii, please help. How do I draw the 2 best fit lines and MS even says something about horizontal line???
When you plot you will get 2 patterns shown on the graph. One horizontal and the other slant line.
Draw to different lines (one for the slant and one for the horizontal)
Extend both of the lines until they intersect, find the x value of the point of intersection.
I got 0.0248 (answers will obviously differ by a specific range)
 
Messages
132
Reaction score
46
Points
38
When you plot you will get 2 patterns shown on the graph. One horizontal and the other slant line.
Draw to different lines (one for the slant and one for the horizontal)
Extend both of the lines until they intersect, find the x value of the point of intersection.
I got 0.0248 (answers will obviously differ by a specific range)

I draw the horizontal line where the y value becomes same right? Like last 2-3 points?
But MS says 2 straight lines and then level off, do I need to draw 2 slanting "best fit" lines through the first few points excluding the horizontal points??? Or just simply 2 lines, one slanting and one horizontal??
 
Messages
176
Reaction score
186
Points
53
I draw the horizontal line where the y value becomes same right? Like last 2-3 points?
But MS says 2 straight lines and then level off, do I need to draw 2 slanting "best fit" lines through the first few points excluding the horizontal points??? Or just simply 2 lines, one slanting and one horizontal??
Yes exactly last 3 points!
No no, just one best fit slant, and one horizontal (Last 3 points).... Like total of 2 best fits as the questions asks. And record the x value of the point of intersection.
 
Messages
132
Reaction score
46
Points
38
Yes exactly last 3 points!
No no, just one best fit slant, and one horizontal (Last 3 points).... Like total of 2 best fits as the questions asks. And record the x value of the point of intersection.

Okay thank you so much. How's your prep for tmrw's p5? I'm writing paper 52, wbu? I've done papers only from 2014-2016. :( Any tips?
 
Messages
187
Reaction score
976
Points
103
Okay thank you so much. How's your prep for tmrw's p5? I'm writing paper 52, wbu? I've done papers only from 2014-2016. :( Any tips?
Though 2 years aren't much but I did like from 2010, and the lastest ones are more important, so you'd do fine.
Did you do all variants?

Also any idea, how do we keep reactants separate until the reaction starts?
like maybe tie a thread to crucible and put the bung. then use thread to empty it. I think I read something like that
 
Messages
52
Reaction score
21
Points
18
ny1 knws hw to measure effect of temp on solubilty?? i knw hw to do measure effect of conc. on solubilty..
 
Messages
176
Reaction score
186
Points
53
Okay thank you so much. How's your prep for tmrw's p5? I'm writing paper 52, wbu? I've done papers only from 2014-2016. :( Any tips?
You got my inbox right? I am not allowed to post long passages, I don't even know why!
 
Messages
176
Reaction score
186
Points
53
Also any idea, how do we keep reactants separate until the reaction starts?
like maybe tie a thread to crucible and put the bung. then use thread to empty it. I think I read something like that
Draw a glass lid in between both the reactants, that can be dragged up for them to come in contact!
OR
You can keep one reaction in some small cylinder which is attached to a small string. To start the reaction, the string is pulled, and the cylinder falls, causing the reactants to mix.
 
Messages
1,394
Reaction score
12,123
Points
523
Though 2 years aren't much but I did like from 2010, and the lastest ones are more important, so you'd do fine.
Did you do all variants?

Also any idea, how do we keep reactants separate until the reaction starts?
like maybe tie a thread to crucible and put the bung. then use thread to empty it. I think I read something like that
Draw a glass lid in between both the reactants, that can be dragged up for them to come in contact!
OR
You can keep one reaction in some small cylinder which is attached to a small string. To start the reaction, the string is pulled, and the cylinder falls, causing the reactants to mix.
I also read another method somewhere. That is to use a DIVIDED FLASK to separate the reagents. To start the reaction, just stir the flask, reactants will be mixed, and the reaction will start.
 
Top