Concentration cells and pH in code

You will write functions for the cells of this lesson. One gives the emf of a concentration cell. One turns an emf into a solubility. One gives a solubility product and one gives a pH. The checker tests them with new numbers.

The idea. For a concentration cell, $E = \dfrac{0.0591\ \text{V}}{n}\log\dfrac{c_{conc}}{c_{dil}}$. When one side is a saturated solution of concentration $s$, solve the same equation for $s$. A salt $\text{MX}_2$ has $K_{sp} = 4s^3$. For a hydrogen electrode and a reference electrode, $\text{pH} = \dfrac{E - E_{ref}}{0.0591\ \text{V}}$.

Your tasks.

1. Complete conc_cell_emf(c_dilute, c_conc, n) so that it returns the emf in volts.
2. Complete solubility_from_emf(emf, c_ref, n) so that it returns the saturated concentration $s$, in mol/L. The reference side has the concentration c_ref.
3. Complete ksp_mx2(s) so that it returns the solubility product of a salt of the type $\text{MX}_2$.
4. Complete ph_from_cell(emf, e_ref) so that it returns the pH.