Question

What is the concentration (M) of a NaCl solution prepared by dissolving 6.6 g of NaCl in sufficient water to give 225 mL of solution? Express your answer using two significant figures.

Answer 1

To find the molarity of a NaCl solution, we convert 6.6 g of NaCl to moles using the molar mass and then divide by the volume in liters. The concentration of NaCl is 0.50 M when rounded to two significant figures.

Step-by-step explanation:

To calculate the molarity (M) of a NaCl solution prepared by dissolving 6.6 g of NaCl in enough water to make 225 mL of solution, we first need to convert mass to moles using the molar mass of NaCl. Sodium chloride (NaCl) has a molar mass of 58.44 g/mol. Therefore:

• Moles of NaCl = mass (g) ÷ molar mass (g/mol) = 6.6 g ÷ 58.44 g/mol = 0.1129 mol

Since molarity is defined as moles of solute per liter of solution, the volume of the solution needs to be in liters:

• Volume of solution = 225 mL = 0.225 L

The molarity can be calculated by dividing the number of moles by the volume in liters:

• Molarity (M) = moles of solute / volume of solution (L) = 0.1129 mol / 0.225 L = 0.502 M

The final concentration of NaCl is therefore 0.502 M, which to two significant figures is 0.50 M.