chemistry - exam practice help!!

posted by .

Given the table below predict the numerical value of the standard cell potential for the reaction:
2 Cr(s) + 3 Cu2+(aq) 2 Cr3+(aq) + 3 Cu(s)

Half Reaction E (volts)
(1) Cr3+ + 3 e- Cr E= -0.74
(2) Cr3+ + e- Cr2+ E=-0.41
(3) Cr2O72- + 14 H+ + 6 e- 2 Cr3+ + 7 H2O
E= 1.33
(4) Cu+ + e- Cu E= 0.52
(5) Cu2+ + 2 e- Cu E= 0.34
(6) Cu2+ + e- Cu+ E= 0.16

how do i do this?

options:

a ) -0.4
b) 2.5
c) 1.08
d) 0.417
e) -1.08

(all units are volts)


i tried

E(products) - E(reactants) but it didn't work, i didn't get any of the options. :S

  • chemistry - exam practice help!! -

    First, you have no arrows. How can you possibly know which are products and which are reactants. I think you do yourself a disservice by not including an arrow.
    For 2Cr + 3Cu^2+ ==> 3Cu + 2Cr^3+
    Divide this into its two half cells.

    Cr(s) ==> Cr^3+ + 3e
    Cu^2+ + 2e ==> Cu(s)

    Now look at the half cell voltages given to you. 1 is the one you want for Cr. That is
    Cr3+ + 3 e- ==> Cr E= -0.74 which is just the reverse of your half cell. Therefore, the voltage for the reverse reaction is +0.74.

    For the Cu, you want #5
    Cu2+ + 2 e- ==> Cu E= 0.34
    Eocell is Eox + Ered = 0.74+0.34 = ?

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. ap chemistry

    I have a lot of questions actually. it's electrochemistry (which is obviously a bunch of fun) 2 electrodes Cr(s)/Cr3+ and Sn(s)/Sn2+ are combined to afford a spontaneous electrochemical reaction. the standard reduction potention in …
  2. Chemistry

    For the following electrochemical cell, what is the correct, balanced reaction?
  3. chemistry

    Given: Cr3+(aq) + 3e¨C  Cr(s); E¡ã = ¨C0.74 V Pb2+(aq) + 2e¨C  Pb(s); E¡ã = ¨C0.13 V What is the standard cell potential for the following reaction?
  4. chemistry

    A voltaic cell is contructed in which a copper wire is placed in a 1.0 M Cu(NO3)2 solution and a strip of gold i placed in a 1.0 M AuNO3 solution. The measured potential of the cell is found to be 1.36V and the copper electrode is …
  5. Chem

    An electrochemical cell based on the decomposition of H2O2 can be constructed based on the half-reactions in the table below. Half-Reaction | Standard Reduction Potential, E° H2O2+ 2e- => 2 OH- | 0.88 V O2+ 2 H2O + 2e- => H2O …
  6. Chemistry

    Given these standard reduction potentials at 25 C 1. Cr3+ + e- ===> Cr2+ E1=-0.407 V 2. Cr2+ + 2e- ===> Cr(s) E2=-0.913 V determine the standard reduction potential at 25C for the half-reaction equation Cr3+ + 3e- ===> Cr(s) …
  7. chemistry

    Given these standard reduction potentials at 25oC: Cr3+ + e- -> Cr2+ (E1^o = -0.407V) Cr2+ + 2e- -> Cr(s) (E2^o = -0.913V) Determine the standard reduction potential at 25oC for the half-reaction equation: Cr3+ + 3e- -> Cr(s) …
  8. Chemistry (Electrochemistry)

    The standard potential for the following galvanic cell is 1.72V : Be(s)|Be2+(aq)||Pb2+(aq)|Pb(s) The standard reduction potential for the Pb2+/Pb half-cell: E = -.13V Calculate the standard reduction potential for the Be2+/Be half-cell. …
  9. chemistry

    3. For the reaction between Cu and Sn the potentials are given below; Cu2+(aq) +2e- -----------> Cu(s) Eºcathode = 0.34 (half-cell potential) Sn(s) -----------> Sn2+(aq) + 2 e- Eºanode = - 0.14 (half-cell potential)
  10. chemistry

    3. For the reaction between Cu and Sn the potentials are given below; Cu2+(aq) +2e- -----------> Cu(s) Eºcathode = 0.34 (half-cell potential) Sn(s) -----------> Sn2+(aq) + 2 e- Eºanode = - 0.14 (half-cell potential) Calculate …

More Similar Questions