Question

The concentration of the stock solution will be approximately 7.50 x 10-5 M. How many milliliters of this stock solution is needed to prepare 50.0 mL of a 1.20 x 10-5 M solution? (Express your answer in the correct number of significant figures.

Answer 1

You want to dilute it 7.50/1.20 times (6.25 times). That means one part original, and 5.25 parts water. What is one part? 50ml/6.25= 8 ml of stock solution. Check significant figures.