Question

What is the molarity of a solution containing 14.6 g of KCl in 281 mL of KCl solution?

Answer 1

0.698 M.

Step-by-step explanation:

Let's remember the concept of molarity: The molarity (M) of a solution is the number of moles of solute dissolved in one liter of solution. To calculate the molarity of a solution, divide the moles of solute by the volume of the solution expressed in liters, like this:

`Molarity\text{ \lparen M\rparen=}\frac{moles\text{ of solute}}{liter\text{s of solution}}=(mol)/(L).`

To find the moles of solute (KCl, in this case) we have to convert 14.6 g of KCl to moles using its molar mass which is 74.5 g/mol, like this:

`14.6\text{ g KCl}\cdot\frac{1\text{ mol KCl}}{74.5\text{ g KCl}}=0.196\text{ moles KCl.}`

Now, let's convert 281 mL to L. Remember that 1 L equals 1000 mL:

`281\text{ mL}\cdot\frac{1\text{ L}}{1000\text{ mL}}=0.281\text{ L.}`

The final step is to replace the data that we obtained in the molarity formula:

`Molarity=\frac{0.196\text{ moles}}{0.281\text{ L}}=0.698\text{ M.}`

The answer would be that the molarity of the solution is 0.698 M.