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The standard reduction potentials at 298...

The standard reduction potentials at 298 K for the following half reactions are given against each
`Zn^(2+) (aq) + 2de hArr Zn(s) - 0.762`
`Cr^(3+)(aq) + 3e hArr Cr(s) - 0.74`
`2H^(+)(aq) + 2e hArr H_(2)(g) 0.00`
`Fe^(3+)(aq) + e hArr Fe^(2+)(aq) 0.77`
Which is the stronger reducing agent ?

A

`Fe^(2+)(aq)`

B

`H_(2)(g)`

C

`Cr(s)`

D

`Zn(s)`

Text Solution

Verified by Experts

The correct Answer is:
D
For an element or an lon to act as a reducing agent, it should itself get oxidised. Hence, the species which has the highest negative value of reduction potential will be most easily oxidised. As `Zn^(2+)` has the highest negative value for reduction, it will have the highest positive value for oxidation and thus will be the best reducing agent among the given options.
The correct order of reducing character is :
`Zn^(2+) (E^(@)= -0.762)`
`gt Cr^(3+) (E^(@)= -0.74) gt H^(+) (E^(@)= 0)`
`gt Fe^(3+) gt (E^(@)= 0.770)`
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The standard reduction potentials at 25^(@)C for the following half reactions are given against each: Zn^(2+) (a.q) + 2e^(-) hArr Zn (s) : " " - 0.762 Cr^(3+) (a.q) 3e^(-) hArr Cr (s) , " " - 0.740 2H^(+) + 2e^(-) hArr H_(2) (g), " " 0.00 Fe^(3+) + e^(-) hArr Fe^(2+) , " " 0.77 Which is the strongest reducing agent?

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At 298 K, the standard reduction potentials for the following half reactions are given. Which acts as anode with others in electrochemical cell Zn^(+2)(aq) + 2e^(-) to Zn(s), -0.762 Cr^(+3)(aq) + 3e^(-) to Cr(s), -0.740 2H^(+)(aq) + 2e^(-) to H_2(g), -0.000 Fe^(+3)(aq) + e^(-) to Fe^(2+)(aq) , +0.762

The standard potentials at 298 K for the following halfreactions are as given Zn^(2+) + 2e underset(larr)(rarr) Zn E^o =- 0/ 762 V . 2 H^+ + 2 Erarr H_2 (g) E^o = 0.000 V Cr^(3+) + 3e underset(larr)(rarr) Cr E^o =- 0.740 V Fe^(3+) 2e rarr Fe^(2+) E^o =0.772 V Which of the following is the strongest reducing agent ?

Knowledge Check

  • The standard reduction potential at 298K for the following half reaction are given against each Zn^(2+)(aq)+2e^(-)hArrZn(s)" "-0.762 Cr^(3+)(aq)+2e^(-)hArrCr(s)" "-0.740 2H^(+)(aq)+2e^(-)hArrH_(2)(g)" "0.000 Fe^(3+)(aq)+2e^(-)hArrFe^(2+)(aq)" "0.770 which is the strongest reducing agent

    A
    Zn(s)
    B
    Cr(s)
    C
    `H_(2)(g)`
    D
    `Fe^(2+)(aq)`

  • The standard reduction potentials at 298 K for the following half reactions are given against eath Zn^(2+)(aq)+2e^(-) rarr Zn(s),-0.762 V Cr^(3+)(aq)+3e^(-)rarrCr(s),-0.740 v 2H^(+)(Aq)+2e^(-)rarrH_(2)(g),0.00V Fe^(3+)(aq)+e^(-)rarrFe^(2+)(aq),0.770 V Which is the strongest reducing agent

    A
    `Zn(s)`
    B
    `Cs(s)`
    C
    `H_(2)(g)`
    D
    `Fe^(3+)(aq)`

  • The standard reduction potentials at 25^(@)C for the following half reactions are given against each: Zn^(2+) (a.q) + 2e^(-) hArr Zn (s) : " " - 0.762 Cr^(3+) (a.q) 3e^(-) hArr Cr (s) , " " - 0.740 2H^(+) + 2e^(-) hArr H_(2) (g), " " 0.00 Fe^(3+) + e^(-) hArr Fe^(2+) , " " 0.77 Which is the strongest reducing agent?

    A
    `Zn`
    B
    `Cr`
    C
    `H_(2)(g)`
    D
    `Fe^(2+) (aq)`
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