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OCR Chemistry F322~ 4th June 2013~ AS Chemistry

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What has 100% UMS been in the past?


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Reply 461
Avatar for AJFShaz
AJFShaz
12
Full marks :L ^^

Here's some notes

http://www.thestudentroom.co.uk/showthread.php?t=2363369
Original post by wndms
Oh I thought that was for combustion. So is formation and combustion kinda a same thin g?

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yea theyre for combustion, but the non-standard conditions can definitely be used for formation. I think thats probably the only answer.
Original post by ReginaPhalange29
What has 100% UMS been in the past?


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Its probably something around 90+
Original post by hakersrok
Hey, quick question about F322 mark scheme.
"DO NOT ALLOW formula with horizontal ––HO OR OH—"
What does this mean? It keeps saying that in the mark scheme but I'm not sure what it is referring to...


I think it means when your drawing a displayed formula, you cant write the OH group with the hydrogen bonded to the carbon, it has to be the oxygen bonded to the carbon then another bond between the oxygen and hydrogen.
Original post by blackstarz
The only thing that is annoying in my opinion is the whole how science work section and green chemistry. Do we need to know the uses of all the polymers? And in how much detail do we need to know about the recycling,sorting and processing and in general the how science work section in module 1


You don't need to know all the uses of polymers. Just how they're disposed of eg. incineration, sorting and recycling, cracking and the problems this causes eg. toxic fumes released. And whats being done to decrease the damage of polymers on the environment eg. development of biodegradable polymers, photodegradable ones, cracking them
Original post by Blashnet
For question 3a on June 2010 paper..

What happens to CH3CH2CH2CH2OH

When you add acid/heat? :confused:

Is this elimination?


yep elimination. the alcohol will be dehydrated to form an alkene and water.
Reply 467
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ImAz
6
Can anyone explain the difference between nucleophilic substitution of a haloalkane to an Amine, and nucleophilic substitution of a haloalkane to an alchohol?
(edited 10 years ago)
Original post by ImAz
Maybe it means when you're drawing out the displayed formula you have to have a bond between the H and O.

Eg C—C—C—OH would be wrong
But
C—C—C—O–H would be right.

Not sure though, email your teacher?




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yea thats right, and the fact that it cant be the hydrogen bonded to the carbon, has to be the oxygen. When the alcohol groups drawn on the left hand side people normally write OH-C- which would be wrong.
OCR suck at publishing UMS boundaries. On AQA it's easier to find out from the UMS calculator. I'm assuming this exam is always full marks for full ums?
Reply 470
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Blashnet
8
Original post by needtosucceed=)
yep elimination. the alcohol will be dehydrated to form an alkene and water.


Greaat! I thought so :biggrin:
Original post by Jimmy20002012
Guessing around 52-55ums :smile:

If ai got around 85 marks in the f322 exam, how manny ums do you think that is?


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Above 138 Ums
Original post by TheFootyKing19
Above 138 Ums


Really, cool :smile:


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If you decrease the temperature in a reaction - I get the equilibrium shifts right but why ?


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ImAz
6
Original post by krishkmistry
If you decrease the temperature in a reaction - I get the equilibrium shifts right but why ?


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The Equilibrium shifts to balance the equations. So the right side of your equation is Exothermic because that takes in heat from the surroundings, and so brings the reaction back to equilibrium.

Basically think about it like this; you're making the reaction colder so your favouring the reverse reaction (left side). The reaction needs to be warmed up so IT favours the right side which will take in heat from the surrounding to counteract you decreasing the temperature.


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(edited 10 years ago)
Original post by ImAz
The Equilibrium shifts to balance the equations. So the right side of your equation is Endothermic because that gives heat to the surroundings, and so brings the reaction back to equilibrium


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What would OCR want you to say do you think - never seen a q where the temperature has been decreased


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Reply 476
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Blashnet
8
Does anybody have any techniques about learning equilibrium? :confused:

I understand the principals, but always get really confused :frown:
Reply 477
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ImAz
6
Original post by krishkmistry
What would OCR want you to say do you think - never seen a q where the temperature has been decreased


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Sorry I made a mistake in my response, thought you'd written increase! Take a look now :tongue:


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Got 89/100 in jan 2010

77 was 120 ums

How many would 89 be

Wish OCR had ums converter like aqa
Original post by Blashnet
Does anybody have any techniques about learning equilibrium? :confused:

I understand the principals, but always get really confused :frown:


I just remember t as if it exothermic in foward direction (- delta H)

Increase temp shifts to left (EXIL)
Decrease temp shifts right. (EXDR)

If its endothermic in foward direction (+ delta H)
Increase temp shifts to the right (ENIR)
Decrease temp shifts to the left (ENDL)

Stupid method put that's how I remember for temperture

As for pressure

Ch4 + br2-----> 4ch3br
Increase pressure shifts to side with fewer moles ( so in this reaction left as it has 2 moles)

Decrease pressure shifts to side with more moles (so in this case the right as there 4 moles)

*only use pressure if has a gas (g) symbol on all products and reactants


My weird methods of remembering things

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