A chemist combines 30.0 mL of 0.500 M hydrochloric acid with 70.0 mL of 0.200 M…
CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance
Problem
A chemist combines 30.0 mL of 0.500 M hydrochloric acid with 70.0 mL of 0.200 M hydrochloric acid in a reaction flask. After thorough mixing, the chemist adds 50.0 mL of distilled water to the resulting solution.
Answer the following questions.
(a) Calculate the number of moles of HCl contributed by each of the two original solutions.
(b) Determine the molarity of HCl in the reaction flask immediately after the two original solutions are mixed but before any water is added.
(c) Compute the molarity of HCl after the additional 50.0 mL of water is added to the flask.
(d) Show that the final molarity obtained in part (c) can also be arrived at by applying a single weighted-average calculation based on total moles and total final volume, and verify that both methods give the same result.