For reactions in which the equilibrium constant is very large or very small, it can be difficult to measure the concentration of all species in solution in order to determine K. An alternative method is to measure the cell potential for a reaction and then to use Eq. 1b to obtain the equilibrium constant. Calculate the equilibrium constant at 25.00 °C for the reaction AgCl(s) → Ag⁺(aq) + Cl^–(aq). The equilibrium constant for this reaction is actually the solubility product, K_sp = [Ag⁺][Cl^–], for silver chloride (Topic 6I).

ANTICIPATE Because silver chloride is almost insoluble, you should expect Ksp to be very small (and E_cell° therefore to be negative).

PLAN Follow the procedure in Toolbox 6N.1.