Chemistry 5070 · O Level · Reversible reactions and equilibrium

Reversible reactions and equilibrium — practice question

Aqueous bromine exists as an equilibrium mixture. $\text{Br}_2(\text{aq}) + \text{H}_2\text{O}(\text{l}) \rightleftharpoons \text{OBr}^-(\text{aq}) + \text{Br}^-(\text{aq}) + 2\text{H}^+(\text{aq})$ Aqueous bromine is orange in colour. The species on the right side of the equation are colourless. Three separate portions of the equilibrium mixture are then each given a small amount of one substance. Which row indicates how the colour of the mixture changes when each substance is added?

  • Aadding sulfuric acid: darker orange; adding solid sodium bromide: darker orange; adding water: darker orange
  • Badding sulfuric acid: darker orange; adding solid sodium bromide: darker orange; adding water: paler orange
  • Cadding sulfuric acid: darker orange; adding solid sodium bromide: paler orange; adding water: darker orange
  • Dadding sulfuric acid: paler orange; adding solid sodium bromide: darker orange; adding water: paler orange

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