So the voltage due To The concentration difference between Some ion x is Equal To The negative of RT divided by ZF, where R is the gas constant, t is the temperature in Kelvin, z is the charge on that ion, and F is Sarah d's constant. We multiply this ratio by the natural log of the ratio of the concentration of the inside to the concentration of the outside. So this is the equation that we can use to actually calculate what the voltage difference is at the equilibrium point for each one of these two ions. So let's begin with sodium. So for sodium. So the gas constant.