Science (086) — AI-generated practice question

(a) Solution X (pH = 2) is strongly acidic in nature. Solution Y (pH = 12) is strongly basic (alkaline) in nature. Values less than 7 indicate acidic solutions and values greater than 7 indicate basic solutions.

(b) Solution Y (pH = 12) has a higher concentration of OH⁻ ions. As pH value increases from 7 to 14, it represents an increase in OH⁻ ion concentration.

(c) The resulting solution will be acidic. Solution X (pH = 2) is a strong acid with very high H⁺ concentration, while Solution Y (pH = 12) is a strong base. Since equal volumes are mixed but the acid's H⁺ concentration (10⁻² M) exceeds the base's OH⁻ concentration (10⁻² M) — actually they are equal — the solution will be neutral (pH ≈ 7), as H⁺ and OH⁻ ions neutralise each other: H⁺(aq) + OH⁻(aq) → H₂O(l).

Source: Chapter 2, Section 2.3

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• pH 2 and pH 12 are equidistant from 7 — pH 2 means [H⁺] = 10⁻² M and pH 12 means [OH⁻] = 10⁻² M. Equal volumes → equal moles of H⁺ and OH⁻ → neutral solution. Examiners expect students to reason through the neutralisation, not just guess "acidic."
• For part (b), remember: higher pH above 7 = more OH⁻ ions.
• Use the phrase "neutralisation reaction" and the ionic equation H⁺ + OH⁻ → H₂O for full marks on part (c).