Define the concept of emf

  • EMF stands for electromotive force, and it is a measure of the energy per unit charge that drives the flow of current in an electrical circuit. 
  • In an electrochemical cell, the EMF is the difference in electric potential between the two electrodes. 
  • The EMF of an electrochemical cell is determined by the Gibbs free energy change of the redox reaction taking place at the electrodes.
  •  If the Gibbs free energy change is negative, the redox reaction is spontaneous, and the EMF is positive. 
  • If the Gibbs free energy change is positive, the redox reaction is non-spontaneous, and the EMF is negative.
CONCEPT OF EMF

 

 

EMF can also be expressed as the Gibbs free energy change (ΔG) per unit charge (Q) using the equation:

EMF = ΔG/Q

  • Where ΔG is the Gibbs free energy change 
  • and Q is the charge. 
The unit of EMF is joules per coulomb (J/C), which is equivalent to volts (V).