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GAMSAT sample paper Unit 9 help

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  • 28-08-2011 10:07am
    #1
    spotsanddots
    Registered Users Posts: 132 ✭✭


    the conversion of sucrose to fuctose and glucose in acid ic solution can be represented by the following eqn

    Sucrose(aq) + H20 (H+ above arrow)-> fructose(aq) + Glucose

    Rate law for rxn is rate =k(H+)(sucrose)

    let the rate f the reaction at pH 3 be r .If all the variable are kept constant except that pH is changed to 2 then the rate will be ??

    so does that mean

    r=k(3)(Sucrose)
    r/3=k(sucrose)
    ?? but whats the story with the ph change of 2?:confused:


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    #2
    imported_guy
    Closed Accounts Posts: 1,141 ✭✭✭imported_guy


    spotsanddots wrote: »
    the conversion of sucrose to fuctose and glucose in acid ic solution can be represented by the following eqn

    Sucrose(aq) + H20 (H+ above arrow)-> fructose(aq) + Glucose

    Rate law for rxn is rate =k(H+)(sucrose)

    let the rate f the reaction at pH 3 be r .If all the variable are kept constant except that pH is changed to 2 then the rate will be ??

    so does that mean

    r=k(3)(Sucrose)
    r/3=k(sucrose)
    ?? but whats the story with the ph change of 2?:confused:

    you should really be posting these in the relevant chemistry/physics forums you will get a much better response


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    #3
    Jammyc
    Registered Users Posts: 1,979 ✭✭✭Jammyc


    pH 2 is ten times as acidic as pH3 and 100 times as acidic as pH4.

    Seeing as the rate is dependant on the H+ concentration, a pH change from 3 to 2 would bring a 10 fold increase in the H+ conc.

    Not sure what the answer would be but thats what I can see in it.


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    #4
    Kbear
    Registered Users Posts: 1 ✭Kbear


    pH = -log[H+]

    A pH 3 = 0.001 M H+
    A pH 2 = 0.01 M H+
    Therefore, at a pH of 2 the concentration of hydrogen ions is 10 times greater than at a pH of 3

    Answer= 10r


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    #5
    spotsanddots
    Registered Users Posts: 132 ✭✭spotsanddots


    your right the answer is 10 times the rate 10r


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