Question

You dissolve 0.37 g of potassium chloride (KCI) in 500 mL of water.

Answer 1

Answer: 0.01 M

Explanation:

Molarity is moles of solute/liters of solution.

To find moles, we need to convert 0.37 g of KCl into moles.

30.098g/mol K + 35.45 g/mol Cl = 65.548 g/mol KCl

$0.37 g*\frac{mol}{65.548g} =0.00564 mol$

Now that we have moles, we need to convert 500 mL to L.

500 mL = 0.5 L

With our moles and liters, we can find molarity.

$\frac{0.00564mol}{0.5L} =0.011289M$

Significant figures is important. Our answer should be 0.01 M.

Answer 2

Answer:

A. 0.01 M

Explanation:

Molar mass (KCl) = 39.1 + 35.5 = 74.6 g/mol

0.37 g KCl * 1 mol/74.6 g = 0.004960 mol

500 mL = 0.5 L

Molarity = mol solute/L solution = 0.004960 mol/0.5 L = 0.01 M