A student measures the pH of pure water at and records a value of 7.00
CHEMISTRY · Single correct · A Level · Chemistry · Acids and bases · Acids and bases
Problem
A student measures the pH of pure water at 50∘C and records a value of 7.00. Based on this measurement, the water sample is best described as
(a) acidic, because Kw is larger at 50∘C than at 25∘C, so [H3O+]>[OH−] in pure water
(b) neutral, because a pH of 7 is defined as neutral regardless of temperature
(c) basic, because the pH that corresponds to neutrality at 50∘C is below 7
(d) indeterminate, because the pH scale itself changes with temperature, so acidity cannot be classified from pH alone