Question

chemist must prepare of hydrochloric acid solution with a pH of at . He will do this in three steps: Fill a volumetric flask about halfway with distilled water. Measure out a small volume of concentrated () stock hydrochloric acid solution and add it to the flask. Fill the flask to the mark with distilled water. Calculate the volume of concentrated hydrochloric acid that the chemist must measure out in the second step. Round your answer to significant digits.

Answer 1

Answer:

1.7mL of the stock solution

Explanation:

...Must prepare 550.0mL with a pH of 1.60 at 25°C

...Fill a 550.0mL volumetric flask

...Concentrated stock of 8.0M

... Round the answer to 2 significant digits

First, with pH we can solve [H⁺] = [HCl] concentration that we need to prepare the solution:

pH = -log[H⁺]

1.60 = -log[H⁺]

10^-1.60 = [H⁺]

0.0251M = [H⁺]

That means we need to dilute the concentrated solution from 8M to 0.0251M, that is:

8M / 0.0251M = 318.5 times

As the final volume of the solution is 550.0mL, the volume of the stock 8M HCl solution must be:

550.0mL / 318.5 times =

1.7mL of the stock solution