A student prepares 100.0 mL of 0.200 M CuSO in a volumetric flask
CHEMISTRY · Single correct · A Level · Chemistry · Amount of substance · Amount of substance
Problem
A student prepares 100.0 mL of 0.200 M CuSO4 in a volumetric flask. Before storing the solution, the student rinses the flask walls with small portions of distilled water and combines the rinse with the main solution. Which of the following best explains how this practice affects the concentration of CuSO4 in the combined solution?
(a) The concentration increases because additional CuSO4 crystals are washed from the flask walls into roughly the same volume.
(b) The concentration decreases because adding rinse water increases the total volume while the amount of CuSO4 remains constant.
(c) The concentration remains 0.200 M because adding distilled water does not change the number of moles of CuSO4 present in the solution.
(d) The concentration becomes approximately 0.100 M, assuming the rinse water doubles the original volume and thereby halves the molarity.