# Solutions of calcium hydroxide and sodium hydroxide are prepared in water at equivalent concentrations. For which solution will [HO^-] be greater?

$\text{Concentration}$ is a measure of the number of particles in solution. You have equal strength concentrations of calcium hydroxide and sodium hydroxides with respect to the metal. Calcium hydroxide, however, delivers twice the hydroxide ion concentration as does sodium hydroxide. The calcium hydroxide solution contains more ions in solution.