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Edexcel chemistry unit 5 - question & answer watch


    (Original post by mik1w)
    well there are many different tequniques depending on the reaction.

    1. colourimetry, first calibrate colourimeter, put sample reacting in it and this will plot results. benefits - no need for sampling so accurate timing. required a coloured reagent or product

    2. sampling at time intervals for titration and analysis, eg. iodine with thiosulphate, or anything that manganate reduces. probloem - error in sampling and reaction may still proceed in sample

    3. pH meter in solution, to plot change in pH over time, can be used to find change in hydrogen ion concentration over time


    define a d-block element (markscheme says something different to my defenition above):

    element whose change in electron configuration over previous element is an extra electon in the d-block. (does not accept "highest energy level electron in d-block)

    Q: why can the rate equation not be determined from the stoichiometric equation?
    d-block element is the element with the last election in a d orbital.
    because the rate equation only involves the compound that is in the rate determing step.
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