Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    16
    ReputationRep:
    http://qualifications.pearson.com/co...e_20130114.pdf

    January 2013 edexcel unit 4

    Question 8 help please.

    I got the order wrt [H+] =2nd order

    I'm stuck with [Br-]
    looking at experiment 1 and 3, [Br-] doubles, [BrO3-] triples and [H+] stays constant. The rate increases by x6 but does this all link to get 1st order wrt [Br-]

    Thanks x
    • Thread Starter
    Offline

    16
    ReputationRep:
    bump
    Offline

    3
    ReputationRep:
    (Original post by Dinaa)
    .
    Kvothe the arcane??
    • Thread Starter
    Offline

    16
    ReputationRep:
    (Original post by thefatone)
    Kvothe the arcane??
    thanks
    Offline

    3
    ReputationRep:
    The rate is 1st order with respect to bromide. You can work this out by what they tell you in the question. You've already correctly determined that the rate is 2nd order with respect to H+. Knowing that the order is 1st order with respect to bromate, you now have enough information to work out the order with respect to bromide.

    As you've stated, the rate increases 6-fold when you increase the concentration of bromate by a factor of 3 and the concentration by a factor of 2. Knowing that the rate with respect to bromate is 1st order, the rate should triple with a 3-fold increase in the concentration of bromate. Now if the rate was 2nd order with respect to bromide then if you doubled the concentration the rate should increase 4-fold. If it was zero order the concentration of bromide would not affect the rate. As the rate doubles with a 2-fold increase in the concentration of bromide.. you can infer that the rate is 1st order with respect to bromide.
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Would you like to hibernate through the winter months?
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.