Turn on thread page Beta
    • Thread Starter


    I stronly believe there is an error in this Q.

    1.05 l at STP = 1.04/22.4 = 0.0464 moles of NO2 gas.

    As there are one mole each of Cu AND of NO2 in 1st reaction,
    therefore the no of moles of copper was also 0.0464.

    No of grams of copper in original brass = 0.0464 X 63.5 = 2.95g

    This implies that there was more copper in the brass than the weight of the brass itself (IMPOSSwhich isIBLE!).

    I think the examiner has mixed up his/her numerator with denominator
    i.e. he/she has done 2/2.95 instead of 2.95/2 to work out original mass of copper (I bet this Q is from Edexcel paper!)

    The answer was probs (a) which is roughly 2/2.95.

    UTTERLY SHAMEFUL of the examiner (unless I am making a blunder which is possible. of course!


University open days

  1. University of Cambridge
    Christ's College Undergraduate
    Wed, 26 Sep '18
  2. Norwich University of the Arts
    Undergraduate Open Days Undergraduate
    Fri, 28 Sep '18
  3. Edge Hill University
    Faculty of Health and Social Care Undergraduate
    Sat, 29 Sep '18
Which accompaniment is best?

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

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