Electrochemical Equilibrium When the force caused by the concentration difference and the force caused by the electrical potential difference are equal and opposite, no net movement of the ion occurs, and the ion is said to be in electrochemical equilibrium across the membrane When an ion is in electrochemical equilibrium, the electrochemical potential difference is called as equilibrium potential or Nernst potentialElectrochemical Equilibrium • When the force caused by the concentration difference and the force caused by the electrical potential difference are equal and opposite, no net movement of the ion occurs, and the ion is said to be in electrochemical equilibrium across the membrane. • When an ion is in electrochemical equilibrium, the electrochemical potential difference is called as equilibrium potential or Nernst potential