Question

How much Sr(OH)2 • 8 H2O (M = 265.76) is needed to prepare 250.0 mL of solution in which [OH–] = 0.100 M?

Answer 1

There are a number of ways to express concentration of a solution. This includes molarity. Molarity is expressed as the number of moles of solute per volume of the solution. We do as follows:

Molarity = mol / L = 0.100 mol OH / L

0.100 mol OH / L ( .250 L ) ( 1 mol  Sr(OH)2 • 8 H2O / 2 mol OH ) ( 265.76 g / 1 mol ) = 3.322 g Sr(OH)2 • 8 H2O needed