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Observed and calculated values for the s...

Observed and calculated values for the standard electrode potentials of elements from Ti to Zn in the first reactivity series are depicted in figure (1):

Explain the following observations:
i. The general trend towards less negative `E^(@)` values across the series
ii. The unique behaviour of Copper
iii. More negative `E^(@)` values of Mn and Zn

Text Solution

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(i) The general trend towards less negative E V values across the series is related to the general increase in the sum of the first and second ionisation enthalpies.
(ii) The high energy to transform Cu(s) to `Cu2+(aq)` is not balanced by its hydration enthalpy. (iii) The stability of the half-filled d sub-shell in `Mn^(2+)` and the completely filled `d^(10)` configuration in `Zn^(2+)` are related to their more negative `E^(@) V` values
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The potential associated with each electrode is known as electrode potential. If the concentration of each species taking part in the electrode reaction is unity (if any appears in the electrode reaction, it is confined to 1 atmospheric pressure) and further the reaction is carried out at 298 K, then the potential of each electrode is said to the standard electrode potential. By convention, the standard electrode potential of hydrogen electrode is 0.0 volt. The electrode potential value for each electrode process is a measure of relative tendency of the active species in the process to remain in the oxidised/reduced form. A negative E^(@) means that the redox couple is a stronger reducing agent than the H^(+)//H_(2) couple. A positive E^(@) means that the redox couple is a weaker reducing agent than the H^(+)//H_(2) couple. The metal with greater positive value of standard reduction potential forms the oxide of greater thermal stability. Which of the following couples will have highest value of emf ?

The potential associated with each electrode is known as electrode potential. If the concentration of each species taking part in the electrode reaction is unity (if any appears in the electrode reaction, it is confined to 1 atmospheric pressure) and further the reaction is carried out at 298 K, then the potential of each electrode is said to the standard electrode potential. By convention, the standard electrode potential of hydrogen electrode is 0.0 volt. The electrode potential value for each electrode process is a measure of relative tendency of the active species in the process to remain in the oxidised/reduced form. A negative E^(@) means that the redox couple is a stronger reducing agent than the H^(+)//H_(2) couple. A positive E^(@) means that the redox couple is a weaker reducing agent than the H^(+)//H_(2) couple. The metal with greater positive value of standard reduction potential forms the oxide of greater thermal stability. Which of the following reactions is not correct ?

Knowledge Check

  • The potential associated with each electrode is known as electrode potential. If the concentration of each species taking part in the electrode reaction is unity (if any appears in the electrode reaction, it is confined to 1 atmospheric pressure) and further the reaction is carried out at 298 K, then the potential of each electrode is said to the standard electrode potential. By convention, the standard electrode potential of hydrogen electrode is 0.0 volt. The electrode potential value for each electrode process is a measure of relative tendency of the active species in the process to remain in the oxidised/reduced form. A negative E^(@) means that the redox couple is a stronger reducing agent than the H^(+)//H_(2) couple. A positive E^(@) means that the redox couple is a weaker reducing agent than the H^(+)//H_(2) couple. The metal with greater positive value of standard reduction potential forms the oxide of greater thermal stability. Which of the following couples will have highest value of emf ?

    A
    `Mg|Mg^(2+) ||Ag^(+)|Ag`
    B
    `Zn|Zn^(2+)||Cu^(2+)|Cu`
    C
    `Zn|Zn^(2+)||Ag^(+)|Ag`
    D
    `Cu|Cu^(2+)||Ag^(+)|Ag`

  • The potential associated with each electrode is known as electrode potential. If the concentration of each species taking part in the electrode reaction is unity (if any appears in the electrode reaction, it is confined to 1 atmospheric pressure) and further the reaction is carried out at 298 K, then the potential of each electrode is said to the standard electrode potential. By convention, the standard electrode potential of hydrogen electrode is 0.0 volt. The electrode potential value for each electrode process is a measure of relative tendency of the active species in the process to remain in the oxidised/reduced form. A negative E^(@) means that the redox couple is a stronger reducing agent than the H^(+)//H_(2) couple. A positive E^(@) means that the redox couple is a weaker reducing agent than the H^(+)//H_(2) couple. The metal with greater positive value of standard reduction potential forms the oxide of greater thermal stability. Which of the following metals will not displace hydrogen from water ?

    A
    Mg
    B
    Zn
    C
    Sn
    D
    Ag

  • The potential associated with each electrode is known as electrode potential. If the concentration of each species taking part in the electrode reaction is unity (if any appears in the electrode reaction, it is confined to 1 atmospheric pressure) and further the reaction is carried out at 298 K, then the potential of each electrode is said to the standard electrode potential. By convention, the standard electrode potential of hydrogen electrode is 0.0 volt. The electrode potential value for each electrode process is a measure of relative tendency of the active species in the process to remain in the oxidised/reduced form. A negative E^(@) means that the redox couple is a stronger reducing agent than the H^(+)//H_(2) couple. A positive E^(@) means that the redox couple is a weaker reducing agent than the H^(+)//H_(2) couple. The metal with greater positive value of standard reduction potential forms the oxide of greater thermal stability. Which of the following oxides will be thermally most stable ?

    A
    `ZnO`
    B
    `MgO`
    C
    `Cu_(2)O`
    D
    `Ag_(2)O`