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    Hey people, I am trying to answer question 6 b) on this paper however the mark scheme is vague and doesn't give a perfect answer on the matter (refer to DCPIP etc.), can anyone formulate a perfect answer for the question?

    Mark Scheme: http://www.edexcel.com/migrationdocu...7_US021143.pdf

    Question Paper (Question 6b): http://www.edexcel.com/migrationdocu...e_20090610.pdf

    Many thanks will positive rep!

    Vitamin C is an acid, DCPIP is a redox dye.

    Makes sense that if you titrate the solution containing Vit C with the redox dye a colour change will occur ( wiki DCPIP and the reactions are pretty simple)

    You'll know the concentration of DCPIP and ( not sure if you actually have too but) the reactions, therefore its possibly to work backwards and calculate the Vit C concentration.

    The exeriment needing to be repeated is pretty obvious, and repition at the same time on various days I think just avoids bias ( possible the plant produced more at different times)

    From what I remember they just want a discription of variables and a graph to check to see if you understand the probably results and know what the 2 types of variables are
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