Turn on thread page Beta

Need help with a chemistry question-electrolysis GCSE watch

    • Thread Starter
    Offline

    16
    ReputationRep:
    I'm currently just revising topics of chemistry in the summer because its the only time I can get things done but I'm stuck on a question for Electrolysis.

    In what situation will hydrogen gas be given out during the electrolysis of an aqueous solution of an ionic solid?
    Offline

    17
    ReputationRep:
    It depends on the relative reactivities of H+ (from the water) and any other cations present.
    Offline

    6
    ReputationRep:
    Electrolysis of solutions:
    • Many ionic substances have very high melting points which takes a lot of energy to melt them and free the ions to move to electrodes in electrolysis. However, some ionic substances dissolve in water and when this happens, the ions also become free to move around.
    • In electrolysis only metal of very low reactivity, below hydrogen in the reactivity series are deposited from their aqueous solutions.
    • For example, when we electrolyse an aqueous solution of copper (ll) bromide, copper ions, Cu2+, move to the cathode and the bromide ions, Br–, move to the anode. Copper (ll) bromide is split into its elements at the electrodes shown in the figure below:


    Copper (ll) bromide → copper + bromide
    CuBr2 (l) → Cu (s) + Br2 (aq)
    The state symbols in the given equation shows that the copper bromide is dissolved in water and the copper formed is solid and the bromine formed dissolves in the water.
 
 
 
The home of Results and Clearing

2,842

people online now

1,567,000

students helped last year

University open days

  1. Bournemouth University
    Clearing Open Day Undergraduate
    Wed, 22 Aug '18
  2. University of Buckingham
    Postgraduate Open Evening Postgraduate
    Thu, 23 Aug '18
  3. University of Glasgow
    All Subjects Undergraduate
    Tue, 28 Aug '18
Poll
How are you feeling about GCSE results day?

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