A student prepares four aqueous solutions at and records the partial data shown below
CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases
Problem
A student prepares four aqueous solutions at 25∘C and records the partial data shown below.
Solution
Reported quantity
I
pH=3.25
II
[OH−]=4.7×10−9M
III
pOH=6.12
IV
[H3O+]=2.0×10−7M
Because laboratory space is limited, the instructor asks the student to characterize each solution fully before continuing the investigation.
(1) For each solution, determine the numerical values of all four of the following quantities to the correct number of significant figures: pH, pOH, [H3O+], and [OH−]. Show your work.
(2) Classify each solution as acidic, basic, or neutral at 25∘C. Justify every classification quantitatively.
(3) Rank the four solutions from most acidic to most basic. Support your ranking with a clear argument based on ionic concentrations rather than pH values alone.
(4) Each solution is then diluted by a factor of 10 with distilled water at 25∘C. Predict whether the acidic/basic/neutral classification of any solution will change after the dilution and explain your reasoning without performing additional numerical calculations.