It was second order with respect to B, and first order with respect to X (the catalyst).

I worked it out using both logarithms and in the normal way because I was really unsure about it too at first. :eek:

Reply 24

Chandru4

Original post by thymolphthalein

Awesome. Atleast I got that right. How about the first question is section B. The type of solution. What the hell was that? Plz say its a buffer solution, got nothing else

Reply 25

AhmedBilal

That biodiesel question was ridiculous!
What was the catalyst and purification method?

(edited 8 years ago)

Reply 26

najma_x1d

Original post by Chandru4

Awesome. Atleast I got that right. How about the first question is section B. The type of solution. What the hell was that? Plz say its a buffer solution, got nothing else

yeah it was buffer

Reply 27

thymolphthalein

Original post by Chandru4

Awesome. Atleast I got that right. How about the first question is section B. The type of solution. What the hell was that? Plz say its a buffer solution, got nothing else

Yep, buffer. You can see that the region was almost flat too, indicating that the pH changes very little when acid is added!

Then you just have to write the generic explanation for a couple of lines about how there is a large reservoir of the substances involved in the buffer and how it will keep pH constant. 3 marks, of which 1 mark will be for saying it's a buffer solution. So 2 marks for the explanation bit.

Reply 28

AhmedBilal

and how did you guys get the enthalpy change in section c?
Please tell me :/

Reply 29

Chandru4

Original post by AhmedBilal

That biodiesel question was ridiculous!
What was the catalyst and purification method?

I wrote catalyst as sulfuric acid, and process as recrystallisation. But i think its fractional distil

Reply 30

Elolel

How hard was the exam? What do u people think the grade boundaries should be?

Reply 31

AhmedBilal

Original post by Chandru4

I wrote catalyst as sulfuric acid, and process as recrystallisation. But i think its fractional distil

I wrote dilute HCL and recrystallization

Reply 32

Chandru4

Original post by Elolel

How hard was the exam? What do u people think the grade boundaries should be?

Hard to say. Alot of people in my exam hall left most of section C blank cause they wasted time on B. Might be low, but you cNt trust edexcel

Reply 33

Fatima SJ

what was the value for k?

Reply 34

Elolel

Original post by Chandru4

Hard to say. Alot of people in my exam hall left most of section C blank cause they wasted time on B. Might be low, but you cNt trust edexcel

Yeah It was a pretty long paper! But the grade boundaries r pretty high for unit 4

Reply 35

thymolphthalein

Original post by AhmedBilal

That biodiesel question was ridiculous!
What was the catalyst and purification method?

Can't remember what I wrote for purification, probably something dumb...

Which catalyst? Do you mean for the reaction of methanol with the triglyceride thing?

According to my notes, it can be any strong alkali so I choose NaOH.