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AQA Chemistry Help 6 Marker

I need help on 7D: http://filestore.aqa.org.uk/subjects/AQA-CHEM5-W-QP-JUN10.PDF

MS: http://filestore.aqa.org.uk/subjects/AQA-CHEM5-W-MS-JUN10.PDF

Can someone please help me with this question, they just seem to bombard you with loads of information, thanks I got 4/6 marks first time round
Reply 1
Original post by Sniperdon227
I need help on 7D: http://filestore.aqa.org.uk/subjects/AQA-CHEM5-W-QP-JUN10.PDF

MS: http://filestore.aqa.org.uk/subjects/AQA-CHEM5-W-MS-JUN10.PDF

Can someone please help me with this question, they just seem to bombard you with loads of information, thanks I got 4/6 marks first time round


Yeeee! I shall help, lemme just do it for ya
Reply 2
Original post by K3001N
Yeeee! I shall help, lemme just do it for ya


You get a 6 Iron : 1 Dichromate ratio---- -

Then divide the 10.00/277.9 = 0.0360 (Original Iron)

Then you do Chromate-- -23.70x0.0100/1000 = 2.37x-4 x 6

Then scale this up 250/25cm3 x 1.422x10-3 = 0.0142

then take this scaled amount away from the original 0.0360-0.0142= 0.0218

0.0218/0.0360 x 100==== 60.5%
Original post by K3001N
You get a 6 Iron : 1 Dichromate ratio---- -

Then divide the 10.00/277.9 = 0.0360 (Original Iron)

Then you do Chromate-- -23.70x0.0100/1000 = 2.37x-4 x 6

Then scale this up 250/25cm3 x 1.422x10-3 = 0.0142

then take this scaled amount away from the original 0.0360-0.0142= 0.0218

0.0218/0.0360 x 100==== 60.5%


Thanks for taking the time out to do so, what i cant get my head around is why you subtract the moles

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