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Edexcel A2 Chemistry Unit 5 ~ 22nd January 2013

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Something like 98%, it was a trick question, because you had to work out the moles of iodine that reacted.

Remember the sodium thiosulfate only reacted with the remaining iodine once the reaction between absorbic acid and iodine had finished. Iodine was in excess remember.

Hoe do you calculate the reacted iodine. Had they given the initial excess iodine added

Reply 201

bhowland1994

Original post by jwijekoon

Hoe do you calculate the reacted iodine. Had they given the initial excess iodine added

well apparently I got it wrong but method was work out the number of moles of iodine that reacted with thiosulfate, subtract this from the number of moles of iodine in the first reaction (which was given to you) and then using this value work out the mass of vitamin c

Reply 202

F1's Finest

Original post by Warlord

Dont know, I think the copper q affected everything else, it made me panic a bit and hence I think the rest of the paper may have suffered as a result. Mcqs were ok, section C was meh, ,B was annoying.

lol you love neg repping me :rofl:

Reply 203

Yeethoven

Original post by jwijekoon

Hoe do you calculate the reacted iodine. Had they given the initial excess iodine added

I think they told us there was excess iodine, and specified 2x10-3 moles of it. The ratio of absorbic acid to iodine was 1:1, so you had to divide the thiosulphate by 2, and then do 2x10-3-(moles worked out from thiosulphate/2) I got 98.7 or 98.6, cant remember which one.

Reply 204

Yeethoven

Original post by James A

lol you love neg repping me :rofl:

think its anger from when you keep saying the chemistry is okay, when it sucked :biggrin:

Wait, how do you know lol? How is your name red?

Reply 205

F1's Finest

Original post by Warlord

think its anger from when you keep saying the chemistry is okay, when it sucked :biggrin:

Wait, how do you know lol? How is your name red?

I'm a sub now, I can see who reps me and also I can have a bigger display pic, colour username and also I can talk with the other subs in the 'backroom' and go to TSR meet ups!

Reply 206

Yeethoven

Original post by James A

I'm a sub now, I can see who reps me and also I can have a bigger display pic, colour username and also I can talk with the other subs in the 'backroom' and go to TSR meet ups!

Sounds cool, how do you become one?

Reply 207

F1's Finest

Original post by Warlord

Sounds cool, how do you become one?

Go to the top of the page, scroll the mouse to your name, go down the drop down box and it will say something along the lines of 'TSR subscription' or 'become a subscriber'!

Reply 208

Yeethoven

Original post by James A

Go to the top of the page, scroll the mouse to your name, go down the drop down box and it will say something along the lines of 'TSR subscription' or 'become a subscriber'!

Oh, you have to pay for it? Meh, forget that. Heard from herts or reading?

Reply 209

F1's Finest

Original post by Warlord

Oh, you have to pay for it? Meh, forget that. Heard from herts or reading?

offer from reading, put it as my firm, withdrew from herts.

Reply 210

Yeethoven

Original post by James A

I knew I would regret saying the above. Ffs that exam was a tough one, especially the section B question about copper. I left out the four marker at the end of the copper question. For naming the compounds A-F I just took an educated guess. Reckon I dropped 2 marks max for multiple choice, 7 marks from the copper question and another 4 or 5 from the rest of the paper

Still though, it should be enough for the 103 ums I need. ******* hell though, that was the hardest unit 5 paper, maybe its on par with the jan 11 unit 5 paper!

lol james! I was reading the previous pages and saw this, what the heck happened to, oh yes, it was on par with previous unit 5 papers :biggrin:

Oh, and I got the same answer as you for the copper disprop thingy, and the benzene mechanism thing.

Reply 211

Yeethoven

Original post by James A

offer from reading, put it as my firm, withdrew from herts.

Yeahhh buddy, knew it was your first choice, congrats. Aab?

Reply 212

F1's Finest

Original post by Warlord

Yeahhh buddy, knew it was your first choice, congrats. Aab?

yhhhh boiii aab

Reply 213

Yeethoven

Original post by James A

yhhhh boiii aab

Haha, nice mate, nice :smile:

Ah man, I even revised well for unit 5 lol, I was prepared for a difficult yet doable paper. Did section A, thought okay. Looked at first page of section B, saw the copper, my heart sunk :biggrin:

Reply 214

NutterFrutter