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

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and the very final question about rate of Iodine disappearing or what not

cheers!

I think I got the disappearance question guys :3

After some searching, it's just to do with the moles - granted I had to go back a bit to see the molar ratios
rate of disappearance of I^- is the rate of production times 2 because I^- to I₂ are in a 2:1 ratio!

S₂O₈^2- + 2I^- --> I₂ +2SO₄^2-

So just to put things in context the rate of disappearance of S₂O₈^2- would be the same as the reaction rate (as the 1:1 ratio) and the rate of production of 2SO₄^2- would be 2 times the rate of iodine production cause of the moles!!

:biggrin:

hope that helps (and is correct) it seems to make sense though

(edited 10 years ago)

Reply 201

Dude Ranch

Can anyone explain to me how you work out the repeating unit? For example 1ai in the january 2013 paper please

Reply 202

Tikara

make sure to get lots of sleep people! I didn't get much last night and feel it affected my exam this morning :frown:

( so make sure y'all are ready and make sure you know all of the experimental techniques like reflux and recrystallisation!!

and Good luck for tomorrow!!!!

Reply 203

Kreayshawn

if i draw the polarity signs on unnecessary atoms will i lose marks?

for example on 3b jan 2013, I usually would have drawn those extra ones in red. will I get penalised for that? not sure when to do it on the atom behind since i see it done like that sometimes but not other times

Reply 204

abzy1234

Original post by Kreayshawn

if i draw the polarity signs on unnecessary atoms will i lose marks?

No you won't get penalised; I would've done the same, as it's best to be safe :smile:

Reply 205

abzy1234

Original post by Tikara

hope that helps (and is correct) it seems to make sense though

Yah! I also finally got this today! Such a cheeky question tbh. Cheers for writing it out; I'll laugh if they ask us the same tomorrow :tongue:

Reply 206

hannah1994

What is the charge on an ethanediote ligand????

Reply 207

Dualcore

Original post by hannah1994

What is the charge on an ethanediote ligand????

2-, and it's ethanedioate

Reply 208

hannah1994

Original post by Dualcore

2-, and it's ethanedioate

thankyou

and ah yeah

Reply 209

Dualcore

Original post by hannah1994

thankyou

and ah yeah

No problem :biggrin:

Reply 210

abzy1234

All the best everyone for tomorrow. I'm guessing it's the last exam for the majority, so try your best to end on a massive high! Best of luck :smile:

Reply 211

amber109

anyone pulling an all-nighter?

Reply 212

RainieXD

Me too bro. T_T with you guys on this

-Worst bit is. I have an exam on thurs. And friday.

Reply 213

RainieXD

Could someone help me with question Q2biii January 2011 :frown:

I'm really stuck for some reason
I thought when finding order with respect to one substance the other two have to be constant concentration right? for each row? So confused! Could someone try explain ^^''

Reply 214

RainieXD

Physics by chance :frown:

Reply 215

RainieXD

Oh man Good luck !! ^^ It'll be fine hopefully :smile:

Reply 216

nukethemaly

I stayed up all of last night for C4, then came home and procrastinated for a bit and woke up like an hour or so ago so now i'm gonna end up doing an all nighter, but hey ho, exams finish tomorrow and i'm gonna sleep for a week straight.

Reply 217

Tomatochuckers

Original post by nukethemaly

Same- all nighter for bio on monday and now again.

#WhoNeedsSleep?

#CirclingChiralCarbonsInstead

Reply 218

nukethemaly

Yeah I saw your post on the unit 4 thing for the unit 5 paper haha, I did okay on it but I'm scared grade boundaries will be high and I won't get an A*/A

Reply 219

Tomatochuckers

Biology unit 5 grade boundaries don't shift much I don't think.

Also, there were less data response questions which although time consuming are generally considered to be pretty easy marks, no easy 5 marker core practical question either.