F n z eel

1 0

ε ε

β χ ( )

,Ψ (3.2)

where χ is a constant depending on the electrolyte type:

Type of Electrolyte 1-1 1-2 1-3 1-4 2-4

2-2 2-1 2-3 3-3

χ 2 3 6 10 16

Then, the contribution of electrostatic interactions with other ions for 1 mol of ions is expressed as

F = N n z eel

1 0

ε ε

β χ

⋅

( ) ,Ψ (3.3)

where NA−1.