(i) Explain why is hydrochloric acid a strong acid and acetic acid, a weak acid. How can it be verified?
(ii) Explain why aqueous solution of an acid conducts electricity.
(iii) You have four solutions A, B, C and D. The pH of solution A is 6, B is 9, C is 12 and D is 7.
(a) Identify the most acidic and most basic solutions.
(b) Arrange the above four solutions in the increasing order of H+ ion concentration.
(c) State the change in colour of pH paper on dipping in solution C and D.
(i) HCl is completely ionised in aqueous solution whereas acetic acid is partially ionised in aqueous solution. HCl gives dark red colour with pH paper whereas CH3COOH gives orange colour.
(ii) It is because acid ionises in aqueous solution and these ions conduct electricity.
(iii) (a) ‘A’ is most acidic and ‘C’ is most basic.
(b) C (10-12) < B (10-9) < D (10-7) < A (10-6)
(c) pH paper will become blue in ‘C’ and green in ‘D’.