Practice Problem 3

At 25^oC, a saturated solution of chlorine in water can be prepared by dissolving 5.77 grams of Cl₂ gas in enough water to give a liter of solution. Calculate the molarity of this solution.

Solution

The key to solving this problem is recognizing that we need to know the number of moles of solute in a solution and the volume of the solution before we can calculate the molarity of the solution. The number of moles of solute in this solution is easy to obtain.

We now know the number of moles of solute (0.0814 mol Cl₂) and the volume of the solution (one liter). The concentration of Cl₂ in this solution is therefore 0.0814 moles per liter, or 0.0814 molar.