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Aqa chem 4/ chem 5 june 2016 thread

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Original post by cuppycake3
Screen Shot 2016-06-21 at 16.22.54.pngcan someone explain this to me please :frown:((((((((

im desperate

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Screen Shot 2016-06-21 at 16.22.54.png


for the equation you filp the more negative electrode and then combine the two equatio s (its like normally combining half equations where you must cancel out the electrons)
Can anyone help me

1. How do you do those 5 mark calculations
2 What half equations do we need to learn for them
because if you write it as the more positive electrode (fe) under the other (h)

then apply the anti clockwise rule

you get 2H+ + 2Fe3+ -> fe2+ + + H2

what am i talking about someone help please
who else is absolutely bricking it for this exam lol.
Someone help please
Why do you x2 for -348 and not 158?
Question 1biii in June 2010 paper
ImageUploadedByStudent Room1466523527.462594.jpg
Mark scheme: http://filestore.aqa.org.uk/subjects/AQA-CHEM5-W-MS-JUN10.PDF


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Original post by Ejsjwwj
for the equation you filp the more negative electrode and then combine the two equatio s (its like normally combining half equations where you must cancel out the electrons)



is the more negative electrode the hydrogen one? how would i know?

sorry I'm being so silly I'm just nervous thank you for your help
Original post by cuppycake3
is the more negative electrode the hydrogen one? how would i know?

sorry I'm being so silly I'm just nervous thank you for your help



Yeah the hydrogen one is the more negative one.

Think of it this way, the more negative one is on the left, the more positive is one the right
Original post by Ejsjwwj
Yeah the hydrogen one is the more negative one.

Think of it this way, the more negative one is on the left, the more positive is one the right


so its nothing with emf tables and clockwise rule then?

i was trying to put the more positive one under the other cell and then apply clockwise rule lol
Original post by cuppycake3
is the more negative electrode the hydrogen one? how would i know?

sorry I'm being so silly I'm just nervous thank you for your help


Reduction occurs at positive electrode. Just remember that and you'll be fine
Original post by Bloom77
Someone help please
Why do you x2 for -348 and not 158?
Question 1biii in June 2010 paper
ImageUploadedByStudent Room1466523527.462594.jpg
Mark scheme: http://filestore.aqa.org.uk/subjects/AQA-CHEM5-W-MS-JUN10.PDF


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X2 for fluorine because one mole of a fluorine molecule becomes two moles of fluorine atoms (F2 -> 2F) which isn't true for calcium.
Original post by zombaldia
Reduction occurs at positive electrode. Just remember that and you'll be fine


You don't know how much that's cleared something up for me...

I always did:

E cell = E RHS - E LHS
= reduction - oxidation
= cathode - anode

And now:
= positive electrode - negative electrode
(edited 7 years ago)
Original post by Suits101
X2 for fluorine because one mole of a fluorine molecule becomes two moles of fluorine atoms (F2 -> 2F) which isn't true for calcium.


But one mole becomes two moles in atomisation, not affinity


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Original post by cuppycake3
so its nothing with emf tables and clockwise rule then?

i was trying to put the more positive one under the other cell and then apply clockwise rule lol


Im not sure what this clockwise rule is, but the value of the hydrogen in the emf table should be lower than the other one, so you use the equation given in the table for hydrogen, then you reverse it and then cancel out electrons and combine
Original post by Suits101
You don't know how much that's cleared something up for me...

I always did:

E cell = E RHS - E LHS
= reduction - oxidation
= cathode - anode


isn't it anode- cathode?
Hi! Would someone be able to explain how to do Chem5's take on q=mc/\T?
It's 2cii http://filestore.aqa.org.uk/subjects/AQA-CHEM5-QP-JUN13.PDF
Thanks!!
Is anyone able to explain June 2010 question 7d about the percentage? Thank you!!
Original post by blueberry389
isn't it anode- cathode?


If it is then that'd solve my problems give me a min might've made a typing error.

Just checked - if it's red - ox when surely it's cath - ano?
(edited 7 years ago)


What do you need explaining?

It's just using the equation:
Delta G = Delta H - T(Delta S)

so when Delta G = 0,
T = Delta H/Delta S


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does anyone know how to do calculation 8C for june 13 paper chem 5
thank you

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