Turn on thread page Beta
    • Thread Starter
    Offline

    1
    ReputationRep:
    ok so i have one question.. this question gives:

    Cu2+|Cu E potential= + 0.34V
    Ag+|Ag E potential= +0.80V

    ok so it asks to write the half equation for :

    the Cu|Cu2+ half cell and the Ag|Ag+ half cell..

    what Im confused about is does it matter which way i write the equation?
    as in, Cu2+ + 2e- --> Cu or Cu --> Cu2+ + 2e-
    would it always be left to right as in Cu2+| Cu would mean Cu2+ + 2e- --> Cu?

    oh and seeing as Cu2+|Cu is 0.34 does that mean Cu|Cu2+ is -0.34?
    or do i need to take into account which one is wjere oxidation is taking place and which one is where reduction is taking place?

    sorry if i dont make any sense!!!
    Offline

    11
    ReputationRep:
    (Original post by celinex)
    ok so i have one question.. this question gives:

    Cu2+|Cu E potential= + 0.34V
    Ag+|Ag E potential= +0.80V

    ok so it asks to write the half equation for :

    the Cu|Cu2+ half cell and the Ag|Ag+ half cell..

    what Im confused about is does it matter which way i write the equation?
    as in, Cu2+ + 2e- --> Cu or Cu --> Cu2+ + 2e-
    would it always be left to right as in Cu2+| Cu would mean Cu2+ + 2e- --> Cu?

    oh and seeing as Cu2+|Cu is 0.34 does that mean Cu|Cu2+ is -0.34?
    or do i need to take into account which one is wjere oxidation is taking place and which one is where reduction is taking place?

    sorry if i dont make any sense!!!
    All the standard REDUCTION potential values are given by eqn like below,

    2H+ + 2e- ----> H2
    (ie gaining electrons hence reduced on the LHS)
    Electrode potential values are not affected by no of electrons transferred, so when calculating electrode potential value difference between two electrodes, you simply minus the RHS - LHS value where in cell diagram, you write:
    oxidation on the LHS, reduction on the RHS.

    Don't change the value of E given, just RHS - LHS. Don't multiply by no of electrons either, unless you are calculating gibbs energy.
    Offline

    0
    ReputationRep:
    (Original post by shengoc)
    All the standard REDUCTION potential values are given by eqn like below,

    2H+ + 2e- ----> H2
    (ie gaining electrons hence reduced on the LHS)
    Electrode potential values are not affected by no of electrons transferred, so when calculating electrode potential value difference between two electrodes, you simply minus the RHS - LHS value where in cell diagram, you write:
    oxidation on the LHS, reduction on the RHS.

    Don't change the value of E given, just RHS - LHS. Don't multiply by no of electrons either, unless you are calculating gibbs energy.


    Can you pm me with the basics of electrode potentials and half cells, I'm really at a loss all three of my books seem to be contradictory...I will be so grateful if you help me...I'm really annoyed at myself I'm not dumb but I just dont understand this section....for instance is Potential difference the same as electrode potential = voltage = electromotive force = E standard?

    Can you break it down, starting with copper and Zinc electrochemical cell.....I really need major help....:o:

    If you help me I will rep you so much (hehehe)

    Of course there is no reason to help me if you don't want to.......
    Offline

    11
    ReputationRep:
    (Original post by Orihime)
    Can you pm me with the basics of electrode potentials and half cells, I'm really at a loss all three of my books seem to be contradictory...I will be so grateful if you help me...I'm really annoyed at myself I'm not dumb but I just dont understand this section....for instance is Potential difference the same as electrode potential = voltage = electromotive force = E standard?

    Can you break it down, starting with copper and Zinc electrochemical cell.....I really need major help....:o:

    If you help me I will rep you so much (hehehe)

    Of course there is no reason to help me if you don't want to.......
    what level are you in? uni or a level?
    Offline

    0
    ReputationRep:
    (Original post by shengoc)
    what level are you in? uni or a level?


    A-level..
    Offline

    11
    ReputationRep:
    (Original post by Orihime)
    A-level..
    sorry mate, won't spend my time writing up everything for you, you should do your independent reading at this stage. Do use chemguide.co.uk, it is excellent for a level chemistry, in my opinion.

    the link below specifies directly to standard electrode potential; with all a level problems, the more you do, the better you become. good luck!

    http://www.chemguide.co.uk/physical/...roduction.html
    Offline

    0
    ReputationRep:
    (Original post by shengoc)
    sorry mate, won't spend my time writing up everything for you, you should do your independent reading at this stage. Do use chemguide.co.uk, it is excellent for a level chemistry, in my opinion.

    the link below specifies directly to standard electrode potential; with all a level problems, the more you do, the better you become. good luck!

    http://www.chemguide.co.uk/physical/...roduction.html

    Do you think that I'm naive or ignorant....I have already checked that website plus my text books as well as the 'doc brown' website....
    Thanks for your 'help' anyway....:yep:
    Offline

    11
    ReputationRep:
    (Original post by Orihime)
    Do you think that I'm naive or ignorant....I have already checked that website plus my text books as well as the 'doc brown' website....
    Thanks for your 'help' anyway....:yep:
    hey hey, offended that easily? you have yet to hear worse really. anyway, didn't mean any harm in saying what i did; did you really don't understand what chemguide is talking about?
    Offline

    0
    ReputationRep:
    (Original post by Orihime)
    Do you think that I'm naive or ignorant....I have already checked that website plus my text books as well as the 'doc brown' website....
    Thanks for your 'help' anyway....:yep:
    Just learned this btw... the most negative value i.e the one closest to zero goes on the LHS, in this case Cu... It would be written as Cu2+ + 2e- --> Cu
    Offline

    11
    ReputationRep:
    (Original post by Orihime)
    Can you pm me with the basics of electrode potentials and half cells, I'm really at a loss all three of my books seem to be contradictory...I will be so grateful if you help me...I'm really annoyed at myself I'm not dumb but I just dont understand this section....for instance is Potential difference the same as electrode potential = voltage = electromotive force = E standard?

    Can you break it down, starting with copper and Zinc electrochemical cell.....I really need major help....:o:

    If you help me I will rep you so much (hehehe)

    Of course there is no reason to help me if you don't want to.......
    By the way, "Potential difference the same as electrode potential = voltage = electromotive force = E standard"

    p.d. is voltage difference between two points, so essentially it is similar to E standard(measured relative to that of H+/H2 made to equal zero).

    But electromotive FORCE, emf, though i think it is a form of force, and not potential. You can measure voltage at one point, but p.d. have to be between two points, similar to standard electrode potentials!
    Offline

    0
    ReputationRep:
    Thanks for the help Shengoc (I wasn't offended but I was just surprised that you thought I didn't do any background reading before asking for help on TSR)...I think that I need to restart this topic from the beginning to work out what I don't know from what I actually know...
    Thank you as well, Devan.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: February 7, 2010

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