Question

You dissolve 0.74 g of potassium chloride (KCl) in 500 mL of water.

What is the molarity of the solution?

Use a periodic table.

Responses

0.1 M
0.1 M

0.5 M
0.5 M

0.01 M
0.01 M

0.02 M
0.02 M

Answer 1

To determine the molarity of the potassium chloride (KCl) solution, we need to follow these steps:

1. Calculate the molar mass of KCl.
- Potassium (K) has an atomic mass of approximately 39.1 g/mol.
- Chlorine (Cl) has an atomic mass of approximately 35.5 g/mol.
- Therefore, the molar mass of KCl = 39.1 g/mol + 35.5 g/mol = 74.6 g/mol.

2. Calculate the number of moles of KCl in 0.74 g.
- Moles = mass (g) / molar mass (g/mol).
- Moles of KCl = 0.74 g / 74.6 g/mol ≈ 0.0099 moles.

3. Convert the volume of the solution from milliliters to liters.
- 500 mL = 0.5 L.

4. Calculate the molarity (M) of the solution.
- Molarity (M) = moles of solute / liters of solution.
- Molarity of KCl = 0.0099 moles / 0.5 L = 0.0198 M.

Thus, the molarity of the solution is approximately 0.02 M.

The correct response is **0.02 M**.