# Question #2af68

Apr 20, 2017

Dilute it using water to lower the concentration. Use the formula ${c}_{i} {V}_{i} = {c}_{2} {V}_{2.}$ Assuming you have 1L of 0.40 M solution, you can solve for ${V}_{2} = \frac{{c}_{1} {V}_{1}}{c} _ 2 = \frac{\left(0.40\right) \left(1\right)}{0.20} = 2 L$ (Remember $V$ is always measured in litres.) Notice that this is two times the initial amount of $1 L$. You can deduce that to reduce the concentration or molarity of a solution from 0.40 M to 0.20 M, you must fill the solution with a volume of water that is equal to the volume of solution.

Good luck :).