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How was your chemistry p5 ?

mujtabashahnawaz

mujtabashahnawaz

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gradient was 4.95, formula was CuSO4.5H2O. Solubility graph was a curve with negative gradient at start. For Q1, planning, i messed it all aur bht bongian mari :/ Time was very less. I did question 2 first, then there was only 25 minutes for me to do planning part or 8 marks and messed it, i am expecting 3/8 in that question, other paper went excellent, i am expecting 22/30, and gt to be below 20. To get A* , how many marks do i need to get in P4. I have A in chemistry in AS, with A in all components
 
abcde

abcde

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VelaneDeBeaute said:
I drew an increasing curve till 25 deg, then decreased it. That was the way it was supposed to be! :p
Click to expand...
Umm, I wonder why an increasing curve is appropriate. It's wouldn't be scientifically rational to conclude that an exothermic reaction isn't exothermic for temperatures below 25*C. I think it was an overall decreasing curve (1) with a solubility of 1g/dm3 at 25*C (1) for a total of two marks. I'd like to know what you have to say because I could be wrong. :)
Here's some solubility data to prove my thinking: http://en.wikipedia.org/wiki/Solubility_table
  1. the solubility of Ca(OH)2 decreases, & thus the Ksp decreases, with temperature
  2. The table lists the solubility in grams per 100 ml H2O
  3. 0.189 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 0 Celsius
  4. 0.182 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 10 Celsius
  5. 0.173 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 20 Celsius
  6. 0.16 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 30 Celsius
  7. 0.141 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 40 Celsius
  8. 0.121 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 60 Celsius
  9. 0.086 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 80 Celsius
  10. 0.076 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 90 Celsius
 
kazi umayer

kazi umayer

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abcde said:
Umm, I wonder why an increasing curve is appropriate. It's wouldn't be scientifically rational to conclude that an exothermic reaction isn't exothermic for temperatures below 25*C. I think it was an overall decreasing curve (1) with a solubility of 1g/dm3 at 25*C (1) for a total of two marks. I'd like to know what you have to say because I could be wrong. :)
Here's some solubility data to prove my thinking: http://en.wikipedia.org/wiki/Solubility_table
  1. the solubility of Ca(OH)2 decreases, & thus the Ksp decreases, with temperature
  2. The table lists the solubility in grams per 100 ml H2O
  3. 0.189 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 0 Celsius
  4. 0.182 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 10 Celsius
  5. 0.173 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 20 Celsius
  6. 0.16 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 30 Celsius
  7. 0.141 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 40 Celsius
  8. 0.121 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 60 Celsius
  9. 0.086 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 80 Celsius
  10. 0.076 grams of Ca(OH)2 "dissolved/ 100 ml H2O" @ 90 Celsius
Click to expand...


is the temperature supposed to vary ? :(
 
A

anishniroula

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i got two anamalous points. but my graph only covered 60% of total graph paper. mine gradient was 5.075 so wa the value of x. but i almost messed up with question 1. i made an increasing curve while it must be decresing(almost of my friends said it). but i think i will get ecf,coz i mentioned same increasing thing in prediction. The planning was not so good. i think i will get 6/10there. and 13 in qno 2 so i get about 19.
what about you guys?
 
00tanveer

00tanveer

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The thing about this exam was that it was OK but question 1 was demanding in the sense that you had to be very fussy about detail and an awful amount of effort had to be put on planning. I nailed question 2 however (which I hope I did :p ). Nonetheless, fingers crossed! Hoping everyone does well Insha Allah! :D
 
J

Jinkglex

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I think i managed to do question 1 well, but i really really messed up in Q2 with only 20 mins left, i only managed to get my table values, to make the axes for the graph and make a few points and joined them with a straight line, and my anomalous points were randomly chosen :/ I just said this and this would be anomalous and gave my reasons, which i guess maybe the reasons atleast will be considered? Wont they? And i wrote the correct formula for the salt BUT i didnt explain how i got there due to lack of time :( And i drew construction lines and wrote the formulae y2 - y1/x2 - x1 for the gradient....could anyone please help me out and see if ANY of what i wrote will secure me marks in Q2? Its the only one stressing me out :( Im hoping to get about 20ish atleast since thats where A*-A lies for P5. Im not looking for any direct answers since 24 hours isnt up, just like, if those general points gain marks. Thanks, whoever helps!
 
littlecloud11

littlecloud11

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Jinkglex said:
I think i managed to do question 1 well, but i really really messed up in Q2 with only 20 mins left, i only managed to get my table values, to make the axes for the graph and make a few points and joined them with a straight line, and my anomalous points were randomly chosen :/ I just said this and this would be anomalous and gave my reasons, which i guess maybe the reasons atleast will be considered? Wont they? And i wrote the correct formula for the salt BUT i didnt explain how i got there due to lack of time :( And i drew construction lines and wrote the formulae y2 - y1/x2 - x1 for the gradient....could anyone please help me out and see if ANY of what i wrote will secure me marks in Q2? Its the only one stressing me out :( Im hoping to get about 20ish atleast since thats where A*-A lies for P5. Im not looking for any direct answers since 24 hours isnt up, just like, if those general points gain marks. Thanks, whoever helps!
Click to expand...

Well from what I've seen in the mark schemes this is how they break up the 3 marks.
Identify and circle the anomalous points (1)
Explain the deviation (too little precipitate, too much precipitate) and then give a reason from the procedure for the anomaly. (1)
The same description for the other point (1)

As for the construction line, you should get a mark but they probably won't give you a mark for the formula because for the second mark you had to deduce the actual values.

I forgot the marks for the very last part. If it had two marks you should get a mark for the correct formula. If it had 1 mark you probably won't.

Don't lose heart, I think the gt will be pretty low.
 
J

Jinkglex

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Well i did manage to deduce gradient from values, if that helps...
littlecloud11 said:
Well from what I've seen in the mark schemes this is how they break up the 3 marks.
Identify and circle the anomalous points (1)
Explain the deviation (too little precipitate, too much precipitate) and then give a reason from the procedure for the anomaly. (1)
The same description for the other point (1)

As for the construction line, you should get a mark but they probably won't give you a mark for the formula because for the second mark you had to deduce the actual values.

I forgot the marks for the very last part. If it had two marks you should get a mark for the correct formula. If it had 1 mark you probably won't.

Don't lose heart, I think the gt will be pretty low.
Click to expand...
 
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