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Arrange the following in the order of their decreasing electrode oxidizing potential Mg, K, Ba, Ca

Option: 1

Ba, Ca, K, Mg 


Option: 2

K, Ba, Ca, Mg


Option: 3

Ca, Mg, K, Ba 


Option: 4

Mg, Ca, Ba, K


Answers (1)

best_answer

As we have learnt,

 

Electrode Potential and EMF of Cells -

It is the potential difference between the two terminals of the cell when no current is drawn from it. It is measured with the help of potentiometer or vacuum tube voltmeter.

Calculation of the EMF of the Cell
Mathematically, it may be expressed as

\begin{array}{l}{\mathrm{E}_{\text {cell }} \text { or } \mathrm{EMF}=\left[\mathrm{E}_{\text {red }}(\text { cathode })-\mathrm{E}_{\text {red }}(\text { anode })\right]} \\ {\mathrm{E}_{\text {eell }}^{\circ} \text { or } \mathrm{EMF}^{\circ}} \\ {=\left[\mathrm{E}_{\text {red }}^{\circ}(\text { cathode })-\mathrm{E}_{\text {red }}^{\circ}(\text { anode })\right]}\end{array}

  • For cell reaction to occur the Ecell should be positive. This can happen only if Ered (cathode) > Ered(anode).
  • Eo cell must be positive for a spontaneous reaction.
  • Rate of reaction is directly proportional to the emf of the cell.
  • The emf of the cell depends on the intensity of the reaction in the cell.
  • It measures free energy change for maximum convertibility of heat into useful work.
  • It causes flow of current from higher value of Eo electrode to lower Eo value electrode.

Difference between EMF and Cell Potential

EMF Cell Potential

It is measured by potentiometer.

It is measured by voltmeter.

It is potential difference between two electrodes when no current is flowing in the circuit.

It is potential difference between two electrodes when current is flowing through the circuit.

It is maximum voltage obtained from cell.

It is less than maximum voltage.

It corresponds to maximum useful work obtained from galvanic cell.

It does not correspond.

 

- wherein

The correct order can be obtained from electrochemical series.

Therefore, Option(2) is correct 

Posted by

vinayak

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