Determining molarity - given grams and volume

Question

What is the molarity of a sodium chloride solution that contains 10.05 g of the solid dissolved in 385 mL of water?

Answer 1

We are looking for the molarity of the solution. Molarity or a type of concentration in chemistry, is defined as moles of solute divided by liters of solution.

M = moles of solute / L solution

In this case we are given grams and mL. We will need to convert grams into moles with the molar mass of sodium chloride (NaCl) and convert the mL into L.

The molar mass of NaCl is 58.44 g/mol. To convert grams into moles, we can divide by the molar mass.

10.05 g / 58.44 g/mol = 0.17197125 mol NaCl

To convert the mL into L, we can divide the given mL by 1000 as 1 L = 1000 mL.

385 mL / 1000 L/mL = 0.385 L

To Calculate our molarity, we can divide the moles we just found by the liters we just found.

0.17197125 moles NaCl / 0.385 L = 0.467 M NaCl

Save all your rounding until the very end to ensure the most accurate answer.