A chemical waste repository contains four unlabeled aqueous samples maintained at

CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases

Problem

A chemical waste repository contains four unlabeled aqueous samples maintained at 25∘C25^{\circ}\text{C}. Analysis of each sample yields the following single piece of information. • Sample W: pOH=8.15\text{pOH}=8.15 • Sample X: [H3O+]=1.3×10−10  M[\text{H}_3\text{O}^+]=1.3\times10^{-10}\;\text{M} • Sample Y: pH=12.04\text{pH}=12.04 • Sample Z: [OH−]=3.2×10−2  M[\text{OH}^-]=3.2\times10^{-2}\;\text{M} (1) Calculate the pH of each sample to two decimal places. (2) Classify each sample as acidic, basic, or neutral at 25∘C25^{\circ}\text{C}. Support every classification with appropriate quantitative evidence. (3) If the temperature of the repository were raised to 60∘C60^{\circ}\text{C} (where Kw>1.0×10−14K_w>1.0\times10^{-14}), identify any sample whose classification might change even if its hydronium and hydroxide ion concentrations remained numerically constant. Provide a brief explanation.

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