Treat each half of the cell as a reversible reaction
So for the Fe one if you remove Fe 3+ then the system would oppose this by converting more Fe 2+ into Fe3+, this also produces more electrons which will decrease the electrode potential causing the overall emf of the cell to inrease.
Hope that helps

Reply 923

Mobs25

2

Original post by sam_xo

LOL But I can't remember them in order from the Periodic table :frown:

I want to know the order off by heart, my teacher had this rhyme thing but I've completely forgotten it! :frown:

??? wot do u mean order?? they are already in order...

Reply 924

sam_xo

Original post by Anon1993

You get a periodic table?! :tongue:

LOL Omg. I just realised I missed out half the point of this question!!!! Revision seriously is messing with my head. Woops :/ I meant the BONDING in the elements in order from Na to Cl. My teacher had this rhyme to help remember the bonding and structures but I can't remember it :frown:

Reply 925

sam_xo

Original post by Mobs25

??? wot do u mean order?? they are already in order...

I missed out half the point of this question lol. I've just realised how dumb this sounds. I meant the BONDING in these elements. There's a rhyme to help remember but I forgotten it :/

Reply 926

Pixiefairy

15

i have this exam tomorrow, i'm screwed, bye bye lovely uni :erm:

Reply 927

Sparkly-Star

13

In Jan 2011 paper, last question last marking point why did they do 1000/5 that's the only bit I don't get! Thanks. :smile:

Edit:

It's ok, got it. I need to remember to use my brain.

(edited 12 years ago)

Reply 928

jamest92

Original post by kogaht

shouldnt more electrons increase the potential?

Well electrons are negative so shouldnt more decrease it ?

Reply 929

NRican

What exactly do we need to know about rechargeable and no rechargeable batteries??

Reply 930

Sakildo

Original post by strawberry_cake

Not too sure but I think someone said 82 earlier :smile:

EDIT: yepp 82 for the jan10 and june10 papers :smile:

Thank you!

Reply 931

Raimu

Anyone else find the specimen paper a lot harder than the 3 real papers?

Reply 932

Wish I Could Change This

1

Original post by NRican

What exactly do we need to know about rechargeable and no rechargeable batteries??

Nothing apart from the equations for hydrogen fuel cells
EDIT: and the social impacts so like that hydrogen is explosive making it difficult to implement yadda yadda

(edited 12 years ago)

Reply 933

Stirlo

Original post by Sparkly-Star

In Jan 2011 paper, last question last marking point why did they do 1000/5 that's the only bit I don't get! Thanks. :smile:

Edit:

It's ok, got it. I need to remember to use my brain.

They are changing it to a concentration conc= moles/volume. The volume 5cm3 =needs to be in dm3. So they've converted that, which simplified multiplies the top by 1000. SOrry that might not make sense.

Basically you have moles/5/1000 which is the same as moles*1000/5

Reply 934

Luke0011

11

Original post by Raimu

Anyone else find the specimen paper a lot harder than the 3 real papers?

Yeah it really is!
It's usually like that though.

Reply 935

Ammy16

Original post by kogaht

what is the answer?

The answer is change in coc: decrease
Explanation: equation moves to the right.
Electrode potential decreases.

Reply 936

jwest

Original post by a23m

Yeah they are like EDTA, its usually because in the reaction, you will for more particles on the product side than the reaction side, so there is an increase in entropy. So when you plug in this increase of entropy into the gibbs equation, "DELTA G" will be more negative.

There is also something to do with equilibrium being very far to the product side, but what i said above is fine to get you the marks.

ahh ok thanks for that, so you get more molecules on products cos the reaction might be for example

[Cu(h20)6]2+ + [EDTA]4- ---> [Cu(EDTA)]2- + 6h20

2 molecules goes to 7 molecules hence the increase the entropy...is that along what you were saying?

Reply 937

Anon1993

Original post by sam_xo

LOL Omg. I just realised I missed out half the point of this question!!!! Revision seriously is messing with my head. Woops :/ I meant the BONDING in the elements in order from Na to Cl. My teacher had this rhyme to help remember the bonding and structures but I can't remember it :frown:

Hahaha

S'okay - i know the feeling :tongue:

but ionic, ionic, both, giant covalent, simple, simple. .
Make up your own rhyme? :tongue:

Reply 938

Mazii

CHM5,
Pleaseee be a decent paper;
and have straight forward questions.
Pleaseeeeeeeeeeeeeeee

Reply 939

a23m

Original post by sam_xo

LOL Omg. I just realised I missed out half the point of this question!!!! Revision seriously is messing with my head. Woops :/ I meant the BONDING in the elements in order from Na to Cl. My teacher had this rhyme to help remember the bonding and structures but I can't remember it :frown:

I think it maybe one of those things you just have to learn. Periodicity is immensely boring, theres not a lot of theory, just memory.

I'd suggest remembering it as...
ionic on the left of the periodic table (sodium and magnesium)
and
covalent on the right of the periodic table
Aluminium is a funny one though, its a bit of both!

AQA - Unit 5 - Energetics, Redox and Inorganic Chemistry

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