Question

How do you calculate the concentration of a solute?

Answer 1

The concentration of a solute is calculated using Molarity. Molarity (M) = moles of solute/Liters solution.

For example: A 5.0 L aqueous solution contains 20. grams of NaCl. Calculate the Molarity of the solution.

The solute is the NaCl. First, find the number of moles of solute by multiplying the amount of NaCl by the molar mass:
20. grams NaCl x 1 mol NaCl/58 grams NaCl = .34 mole NaCl

Then, divide the number of moles of the solute by the liters of the solution:
.34 mole/5.0 L = .068 M