- The acid‑base character of the oxides of elements depends on their position in the periodic table.
(a)
(i) State one environmental problem caused by sulfur dioxide, SO₂. [1]
(ii) Write an equation to show how sulfur dioxide reacts in the atmosphere to produce a secondary pollutant. [1]
(b) A solution was prepared by dissolving 0.100 mol of sodium oxide in distilled water and making the total volume up to 1.00 dm³.
(i) Write the equation for the reaction between sodium oxide and water. [1]
(ii) Calculate the pH of the solution. [2]
(c) Hydrocyanic acid, HCN(aq), has Kₐ = 6.17 × 10⁻¹⁰.
(i) Determine the pH of a 0.202 mol dm⁻³ aqueous solution of hydrocyanic acid. [3]
(ii) State one assumption made for your calculation in (c)(i). [1]
(iii) State the composition of a buffer solution containing hydrocyanic acid. [1]