This discussion is now closed.

Check out other Related discussions

F334 (19/06/2013 9:00AM) - Salters Chemistry (Chemistry of Materials) Revision Thread

Scroll to see replies

Reply 140

desiboy20395

Hi

F334 JAN 2013 - Last question. how do you calculate rate of disappearance?!?!

Reply 141

abzy1234

Original post by :)ella

Does anyone have a copy of the Jan 13 paper?

I'm so nervous for tomorrow :frown:

January Paper.pdf
January MS.pdf

Don't worry! It's only natural to get exam nerves now; best thing to do is go over you notes, finish off them past papers; so you can gain confidence for tomorrow. Try your best, and you'll get what you put in :smile:

(edited 10 years ago)

Reply 142

Tikara

Original post by abzy1234

Attachment not found

Don't worry! It's only natural to get exam nerves now; best thing to do is go over you notes, finish off them past papers; so you can gain confidence for tomorrow. Try your best, and you'll get what you put in :smile:

thanks wsa just looking for this :P

wait it's not workinng :frown:

Reply 143

abzy1234

Original post by Tikara

thanks wsa just looking for this :P

wait it's not workinng :frown:

Re-uploaded them :smile:

Reply 144

MTI

hay guys im probably missing something simple here but how do you know what the oxidation state of Cr is in Na2CrO4. Its question 2aii in the jun 12 paper http://www.ocr.org.uk/Images/131295-question-paper-unit-f334-chemistry-of-materials.pdf

Reply 145

Tikara

Original post by MTI

oxygen is always -2
Na is group 1 so +1

totalling them up gives +2 -8 = -6
So for the whole molecule to be neutral the Cr must have +6 state :smile:

Reply 146

super121

Original post by MTI

You should know what Na is +1 while Oxygen is always -2, so Cr has an oxidation state of +6 :smile:

Posted from TSR Mobile

Reply 147

MTI

Original post by Tikara

oxygen is always -2
Na is group 1 so +1

totalling them up gives +2 -8 = -6
So for the whole molecule to be neutral the Cr must have +6 state :smile:

Original post by super121

You should know what Na is +1 while Oxygen is always -2, so Cr has an oxidation state of +6 :smile:

haha thank you :smile:

i feel silly now for not knowing Na is +1 :colondollar:

(edited 10 years ago)

Reply 148

Jlane5000

Original post by desiboy20395

Hi

F334 JAN 2013 - Last question. how do you calculate rate of disappearance?!?!

I was just about to ask this to, does anyone know?

All i can assume is that to make iodine (I₂) (i.e the rate of dissapearance of I-) is twice the rate given because you need 2I- to make I2. I have absolutely no idea if that is right but its all i can think of to justify getting the answer of 2.0 x 10^-5. Hopefully someone else can confirm or correct me :colondollar:

(edited 10 years ago)

Reply 149

lollage123

http://www.ocr.org.uk/Images/79818-question-paper-unit-f334-chemistry-of-materials.pdf

question 1div, how does going over the end point make concentration of e300 seem lower? I don't understand this at all. (Or that rate of dissapearrance of i2 on that other paper. **** iodine)

Reply 150

:)ella

Original post by abzy1234

Thank you

Reply 151

:)ella

Just did the Jan 13 paper and I got a worse mark than I did in January :frown:

Reply 152

hannah1994

Do Tm and Tg like go up with each other?
What I mean is say Tm is 'higher than average' does that mean Tg is 'higher than average'?

Reply 153

Kreayshawn

what colours of compounds/ions etc do we need to have memorised for tomorrow? do we need to remember all the complex ion colours?

Reply 154

Tikara

Whats the difference between a condensation reaction and an elimination reaction? I thought condensation was losing water but HCl can be lost too :frown:

Reply 155

Stardust95

Can someone explain the difference between secondary and tertiary structure for me? I know it's really simple but I never know how to write it... :/

Reply 156

Stardust95

Original post by Tikara

Whats the difference between a condensation reaction and an elimination reaction? I thought condensation was losing water but HCl can be lost too :frown:

Condensation is two molecules coming together and creating a small molecule (water/HCl..) but elimination is where one molecule looses water/HCl :smile:

(I think!)

Reply 157

Tikara

Original post by Stardust95

Condensation is two molecules coming together and creating a small molecule (water/HCl..) but elimination is where one molecule looses water/HCl :smile:

(I think!)

so a small molecule is lost completely from one molecule in elimination and from both molecules in condensation?

Reply 158

Tikara

of all the atoms we learn about I think Nitrogen is my favourite

Reply 159

Dualcore

Original post by Tikara

Whats the difference between a condensation reaction and an elimination reaction? I thought condensation was losing water but HCl can be lost too :frown:

A condensation reaction is an addition reaction followed by and elimination, whereas an elimination is a loss of a small molecule.