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Wjec ch5 22 june 2016 thread

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Original post by Rhyss01
Dw lose a mark that's all due to error carried forward. I also had a 1183 or something for entropy because it was 8 molecules of water used and stuff so I multiplied the entropic by the molecules. Few marks gone there. As for the formation of BaCl2 I had a positive answer of 752. delta H equals all of them plus the enthalpy of formation and just rearranged them:/ don't know it'll it's right or whether it's error carried forward again

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Was the entropy in section B?? I'm pretty sure I multiplied the entropy by the number of molecules too but I got 530 for the entropy change?
Can anyone remember what they got for the value of Kp, and the value of the enthalpy of combustion of methane??
Original post by sumeyyatontus
Was the entropy in section B?? I'm pretty sure I multiplied the entropy by the number of molecules too but I got 530 for the entropy change?
Can anyone remember what they got for the value of Kp, and the value of the enthalpy of combustion of methane??


530 is correct for the entropy change and for the combustion value for methane, you had to remember to use two x enthalpy of formation of water in the calculation.
(edited 7 years ago)
Original post by Firestartc
530 is correct for the entropy change and for the combustion value for methane, you had to remember to use two x enthalpy of formation of water in the calculation.


I did, but I feel like my value was off :/ can't remember what it was now but I'm sure it was more negative than the hydrogen value
Original post by sumeyyatontus
I did, but I feel like my value was off :/ can't remember what it was now but I'm sure it was more negative than the hydrogen value


Yea, but the next question asked to show hydrogen released more energy per unit mass, not per mole.
Reply 84
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bzira
Does anyone know where I can find the paper?
Original post by Firestartc
Yea, but the next question asked to show hydrogen released more energy per unit mass, not per mole.


Ohh.. What did you write for the next part?
Original post by sumeyyatontus
Ohh.. What did you write for the next part?


I just worked out how much energy 1gram of hydrogen released and 1 gram of methane released. The 1gram of hydrogen released more.
Original post by sumeyyatontus
Was the entropy in section B?? I'm pretty sure I multiplied the entropy by the number of molecules too but I got 530 for the entropy change?
Can anyone remember what they got for the value of Kp, and the value of the enthalpy of combustion of methane??


Probably looked at the equation wrong. I used the entropy of products - the entropy of reactants. I may be way off but for Kp I had 32^2 / 18 x 52^3 hahahah probably had that wrong too but it seemed right since it said 84 units at the end or start of reaction
Sounds as if I've completely screwed all the calculations in that exam ffs

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Avatar for bzira
bzira
Does anyone remember what other questions were on the page that had the copper 6 marker? I think i might have missed out a section :frown:
Original post by Rhyss01
Probably looked at the equation wrong. I used the entropy of products - the entropy of reactants. I may be way off but for Kp I had 32^2 / 18 x 52^3 hahahah probably had that wrong too but it seemed right since it said 84 units at the end or start of reaction


Do you remember how many marks this calculation was?
Original post by Firestartc
Do you remember how many marks this calculation was?


Probably 2 or 3

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Does anyone remember the properties of transition elements that were given to us in the question? There were 3 i think
Original post by Faisalshamallakh
Does anyone remember the properties of transition elements that were given to us in the question? There were 3 i think


Variable oxidation states, form complexes, can't remember the third one
Original post by sumeyyatontus
Variable oxidation states, form complexes, can't remember the third one


form coloured compounds pretty sure
Original post by wwwwwwwwwwwf
form coloured compounds pretty sure


Is having partially filled d orbitals a possible answer?
Original post by Firestartc
Is having partially filled d orbitals a possible answer?

Yes
Original post by Firestartc
Is having partially filled d orbitals a possible answer?


Thats the answer I gave so i guess ya
Anyone get something in the -800s for the combustion question?
Wasn't sure how to do the next question after that one...
Original post by thatcooldude2.0
Anyone get something in the -800s for the combustion question?
Wasn't sure how to do the next question after that one...


I did then I changed it and got +104, which I'm pretty sure is wrong but w.e

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