Enter the ion concentrations of two solutions to determine the liquid junction potential between them. This calculator helps in understanding the potential difference that arises when two ionic solutions of different concentrations are in contact.

Liquid Junction Potential Formula

The following formula is used to calculate the liquid junction potential:

LJP = 59 * log10(C1 / C2)

Variables:

  • LJP is the liquid junction potential (millivolts, mV)
  • C1 is the ion concentration of the first solution (mol/L)
  • C2 is the ion concentration of the second solution (mol/L)

To calculate the liquid junction potential, take the logarithm (base 10) of the ratio of the ion concentrations of the two solutions and multiply by 59, which is the approximate millivolt value at room temperature (25°C) according to the Nernst equation.

What is Liquid Junction Potential?

Liquid junction potential is the potential difference that develops when two ionic solutions of different concentrations come into contact. It is an important factor in electrochemistry and is considered when measuring the potential of electrochemical cells, especially in the use of reference electrodes. The liquid junction potential arises due to the differing rates at which ions migrate across the junction, leading to charge separation and a potential difference.

How to Calculate Liquid Junction Potential?

The following steps outline how to calculate the Liquid Junction Potential.

  1. First, determine the ion concentration of the first solution (C1) in moles per liter (mol/L).
  2. Next, determine the ion concentration of the second solution (C2) in moles per liter (mol/L).
  3. Next, gather the formula from above = LJP = 59 * log10(C1 / C2).
  4. Finally, calculate the Liquid Junction Potential (LJP) in millivolts (mV).
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Ion concentration of the first solution (C1) = 0.1 mol/L

Ion concentration of the second solution (C2) = 0.01 mol/L