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OCR B (Salters) F332 Tuesday 4th June 2013 Exam Discussion (Now Closed)

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Can someone please explain to me how you know if a reaction is described as electrophilic or nucleophilic. Also what is the difference between an electrophile and a nucleophile ? Thank you so much in advance . :colondollar:

Reply 21

super121

I've got a list of reagents and conditions we need to learn, I can attach them if anyone's wants them :smile:

Reply 22

nukethemaly

Original post by super121

i've got a list of reagents and conditions we need to learn, i can attach them if anyone's wants them :smile:

yes pleaseee! :d

Reply 23

nukethemaly

Original post by madrevision

I can never tell the difference between if its electrophilic substitution or electrophilic addition or nucleophilic addition or substitution, I've kind of just committed to memory which families do what. Electrophiles carry a positive charge and hence are attracted to electron-rich regions since they carry a negative charge. Whereas a nucleophile carries an overall negative charge or a slight negative charge and hence are attracted to species with positive charges.

(edited 11 years ago)

Reply 24

madrevision

thank you,that cleared things up :smile:

Reply 25

super121

Original post by nukethemaly

yes pleaseee! :d

Here you go :smile:

Reagents and conditions.pdf624.2KB

Reply 26

cheetahs56

Original post by madrevision

thank you,that cleared things up :smile:

Also addition is when nothing is removed and something is added (i.e. breaking the double-bond and attaching itself), whilst subsitution is when something is removed and the other thing taking it's place (e.g. Bromine displacing Iodine from solution). Does that make sense?

Reply 27

nukethemaly

Original post by super121

Here you go :smile:

Thank you!

This is REAAAALLLY amazing!

(edited 11 years ago)

Reply 28

madrevision

Original post by super121

Here you go :smile:

Dude when I get my A i'm gonna send you flowers and chocolate lol :biggrin:

but seriously thank you, much appreciation

Reply 29

madrevision

Yes finally simple explanation yay :banana:

thank you for helping out :smile:

Reply 30

madrevision

Original post by blondie24

So i'm currently revising atmosphere and i was doing the assignments in the storylines and am totally stuck on Assignment 11! can somebody help me please! i'll post the question as well :smile:

'In 2001, the concentration of CO2 in the atmosphere at Mauna Loa was 370ppm(by volume). The total mass of CO2 in the...

Now answer the following questions
QUOTE]
Do you still need help ?

Reply 31

madrevision

Guys i'm thinking about making a folder with common question that come up regularly and model answers for them. Would anyone else want to use it- I just want to know if it's worth doing :smile:

Reply 32

FuLLuPMepOrtION

Original post by King Hotpie

I need to smash this exam to make up for my coursework... Does anyone else feel that Salters Coursework must have spawned from the very depths of hell?

Its literally the easiest part of the course, just wait until the A2 coursework. It's what gives Salters it's reputation for being by far the hardest exam board, it's SERIOUSLY ****ing hard.

Reply 33

super121

Original post by madrevision

Dude when I get my A i'm gonna send you flowers and chocolate lol :biggrin:

but seriously thank you, much appreciation

Welcome

Let's hope you get an A then :P this is the biggest unit so it's really worth doing well in it, as A2 is absolute hell

Posted from TSR Mobile

Reply 34

blondie24

[QUOTE="madrevision;42235731"]

Original post by blondie24

So i'm currently revising atmosphere and i was doing the assignments in the storylines and am totally stuck on Assignment 11! can somebody help me please! i'll post the question as well :smile:

'In 2001, the concentration of CO2 in the atmosphere at Mauna Loa was 370ppm(by volume). The total mass of CO2 in the...

Now answer the following questions
QUOTE]
Do you still need help ?

Yes please :colondollar:

Reply 35

yugiohtheawesome

Hi Everyone

I've got the AS coursework coming up this week, and I was wondering if anybody has any tips for me? Can't afford to fail this part of the course as the rest is already screwed as it is :l

Reply 36

madrevision

Original post by blondie24

So i'm currently revising atmosphere and i was doing the assignments in the storylines and am totally stuck on Assignment 11! can somebody help me please! i'll post the question as well :smile:

'In 2001, the concentration of CO2 in the atmosphere at Mauna Loa was 370ppm(by volume). The total mass of CO2 in the atmosphere was estimated to be about 2760Gt at that tim (1 Gt= 1 gigatonne = 1 x 10^9 tonnes.)
Through the 4 years from 2001 to the end of 2004, it is estimated that 34Gt of fossil fuels were burned throughout the world.
In 2004 the measured % of CO2 in the atmosphere at Mauna Loa was found to be 377ppm (by volume).

Now answer the following questions:
a Assume that the 34Gt of fossil fuels burned in the four years were all C. Calculate the mass of CO2 formed by burning this mass of fuel.
b Calculate the new total mass of CO2 in the atmosphere at the end of 2004, assuming that the extra CO2 came only from burning fossil fuels and that it stayed in the atmosphere.
c By what % would you expect the concentration of CO2 in the atmosphere to have increased in the 4 years?
d By what % did the concentration of CO2 in the atmosphere actually increase in the 4 years?

I wasn't too sure either but I got some genius to help me lol. Here you go a) CO2 has RFM 12+16+16 = 44. Percentage by mass of carbon in CO2 is 12/44 = 3/11. There are 34Gt extra carbon, which is 3/11 of total mass of CO2. 34=3/11 m >> (34x11)/3 = m = 125Gt
b) 2760+125 = 2885Gt
c) 125/2760 x100% = 4.53%
d) 7/370 x100% = 1.89%

Reply 37

nukethemaly

Original post by madrevision

Guys i'm thinking about making a folder with common question that come up regularly and model answers for them. Would anyone else want to use it- I just want to know if it's worth doing :smile:

Yep! That's a brilliant idea actually.