Question

Determine the molarity of a solution prepared by dissolving 65 grams of calcium chloride in 500 mL of solution

Answer 1

Molarity corresponds to the number of moles of solute in a liter of solution. So, we have the following expression:

`\text{Molarity = }\frac{\text{Mol of calcium chloride}}{\text{Liters of solution}}`

We will use molecular weight (MW) to calculate the moles present in 65 g of calcium chloride.

MW= 110.98 g/mol

`\begin{gathered} \text{Mol of calcium chloride =}\frac{\text{ Mass of calcium chloride}}{\text{Molecular weight}} \\ \text{Mol of calcium chloride }=\text{ }\frac{\text{65g}}{110.98\text{ g/mol}} \\ \text{Mol of calcium chloride }=0.58mol \end{gathered}`

So, molarity will be:

Volume: 500mL = 0.5 L

`\text{Molarity = }\frac{\text{0.58 mol}}{0.5\text{ L of solution}}=1.2M`

The answer will be 1.2 M