Science — AI-generated practice question

A strong acid completely ionises in water, producing a large number of H⁺ ions, while a weak acid partially ionises, producing fewer H⁺ ions.

Distinction: Using a universal indicator or pH paper, a strong acid shows a lower pH value than a weak acid of the same concentration.

Example: If we take 1 molar HCl (strong acid) and 1 molar acetic acid (CH₃COOH, weak acid), HCl produces more H⁺ ions and shows a lower pH, whereas acetic acid produces fewer H⁺ ions and shows a comparatively higher pH, even though both concentrations are the same.

Source: Chapter 2, Section 2.3; Chapter 4, Section 4.4.2

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• Examiners expect the definition of strong vs. weak acid in terms of degree of ionisation / number of H⁺ ions produced.
• The HCl vs. acetic acid example is directly from the textbook (Section 2.3) and must be included for full marks.
• Mentioning the pH/universal indicator as the method of distinction earns the "how to distinguish" mark.
• Do not simply say "strong acid has more H⁺" without linking it to pH or ionisation — that costs a mark.