How much water had to be added to 50.0 mL of the first solution to obtain the second solution?

Question

Quizplus · Accepted Answer

Since the second solution has half the concentration of the first solution, it means that half of the 50.0 mL must be the solute (assuming that the volume of the solution didn't change when water was added). Therefore, the solute is present in 25.0 mL of the first solution. To make the second solution, we need to dilute the solute with an equal amount of solvent (water). So, we need to add 25.0 mL of water to the 50.0 mL of the first solution, which gives a total volume of 75.0 mL for the second solution. To check that the concentration has halved, we can see that the same amount of solute (represented by 25.0 mL) is now dissolved in 75.0 mL of solution rather than 50.0 mL. 25/75 = 1/3 = 0.333, which is half of the initial concentration of 0.666 M. Therefore, we need to add 25.0 mL of water to the 50.0 mL of the first solution, giving a total volume of 75.0 mL for the second solution. This means that 33.3 mL of water was added to the first solution.

How Much Water Had to Be Added to 50