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Edexcel IAL Chemistry Units4&5

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I wrote distillation for the oil purification. Re-crystallization seems illogical and fractional distillation would separate each component of the oil.
Haha yeah, btw how did you get the enthalpy change? In section C?
Original post by AhmedBilal
Haha yeah, btw how did you get the enthalpy change? In section C?

I just did products - reactants. Got a really high negative value and since its combustion im assuming its right.
Original post by Trixenity
I just did products - reactants. Got a really high negative value and since its combustion im assuming its right.


I did only products. I thought because it's enthalpy change of formation it would be ok.
did the food crop advantage disadvantage question ask for alternative fuels?
Original post by AhmedBilal
I did only products. I thought because it's enthalpy change of formation it would be ok.

I'm not sure. Enthalpy change of formation is formation from elements though right ?
Original post by Trixenity
I'm not sure. Enthalpy change of formation is formation from elements though right ?

Do you rmb the Stotal?
Original post by Chandru4
Do you rmb the Stotal?

For that question first you had to fill the table. Then you had to find enthalpy change. Then Ssystem. Then Ssurroundings. The next question had to do with increasing the temp and the effect on yield. I dont think there was an Stotal question.
Original post by Trixenity
For that question first you had to fill the table. Then you had to find enthalpy change. Then Ssystem. Then Ssurroundings. The next question had to do with increasing the temp and the effect on yield. I dont think there was an Stotal question.


The surrounding and S total question were in one paragraph? You had to find Surrounding and then find S total.
Original post by thymolphthalein
The surrounding and S total question were in one paragraph? You had to find Surrounding and then find S total.

What do you mean ? Stotal was asked in the same part of the question ?
Original post by Trixenity
What do you mean ? Stotal was asked in the same part of the question ?


Yes, that's what I mean.

Unless I hallucinated the whole thing. :tongue:
What was the gas used in GC?
Please say ammonia.....
The same question where you had to find Ssurrounding you had to find Stotal too.

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I only found Ssurrounding :frown: .
I did CO2 for the gas.
Original post by Trixenity
I only found Ssurrounding :frown: .
I did CO2 for the gas.


Yeah, same for the CO2.

Can't remember what my reasoning was for choosing it though.
Original post by thymolphthalein
Yeah, same for the CO2.

Can't remember what my reasoning was for choosing it though.

It was an MCQ, you dont need a reason :biggrin:

Was the name of ester Y ethyl dodecanoate ?
Original post by Trixenity
I only found Ssurrounding :frown: .
I did CO2 for the gas.


No its actually Oxygen. It says so in my textbook.
Original post by Trixenity
It was an MCQ, you dont need a reason :biggrin:

Was the name of ester Y ethyl dodecanoate ?


Yes. :smile:

Ahah, I mean I don't remember why I picked it. I try to reason out my answers, helps me eliminate the wrong options.
Original post by thymolphthalein
The surrounding and S total question were in one paragraph? You had to find Surrounding and then find S total.


Do u rmb your sTotal?
Original post by Chandru4
No its actually Oxygen. It says so in my textbook.


My notes say that in the mobile phase of gas chromatography you can use nitrogen, helium, argon, carbon dioxide etc. Sooo idk.

Edit: I googled and found this. http://teaching.shu.ac.uk/hwb/chemistry/tutorials/chrom/gaschrm.htm along with a bunch of other pages on the use of carbon dioxide being used in gas chromatography.
(edited 8 years ago)

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