A student has two solutions of a substance; Solution-1:25M, 400ml and Solution-2:30M, 300M. What is the molarity of the final solutions if these two solutions are mixed?

The molarity of the final solution is 1.7 M

Explanation:

The parameters given are;

First solution = 400 ml of 1.25 M

Second solution = 300 ml of 2.30 M

Therefore, we have;

First solution contains 400/1000 * 1.25 moles = 0.5 moles of the substance

Second solution contains 300/1000 * 2.30 moles = 0.69 moles of the

Hence the sum of the two solutions contains 0.5 + 0.69 = 1.19 moles of the substance

The volume of the sum of the two solutions = 400 ml + 300 ml = 700 ml

Hence we have the concentration of the final solution presented as follows;

700 ml contains 1.19 moles of the substance

Therefore;

1000 ml will contain 1000/700 * 1.19 = 1.7 moles

The molarity of the final solution = The number of moles per 1000 ml = 1.7 M.