Final answer:
To prepare 100 ml of a 0.10 M solution from a 0.20 M solution, 50 ml of the 0.20 M solution must be diluted.
Step-by-step explanation:
To find out what volume of 0.20 M solution must be diluted to give 100ml of a 0.10 M solution, one can use the dilution formula M1V1 = M2V2, where M1 and V1 are the molarity and volume of the concentrated solution, and M2 and V2 are the molarity and volume of the diluted solution. Given that M2 equals 0.10 M and V2 equals 100 ml, we can rearrange the equation to solve for V1, the volume of the 0.20 M solution needed for dilution.
By substituting our values into the equation: (0.20 M) × (V1) = (0.10 M) × (100 ml), and solving for V1, we determine that the required volume is 50 ml. Hence, 50 ml of a 0.20 M solution is needed to prepare 100 ml of a 0.10 M solution after dilution.