A student investigated the kinetics of the reaction between bromate(V) ions and bromide ions in acidic conditions.
(aq) + 5Br– (aq) + 6H+ (aq) → 3Br2(aq) + 3H2O(l)
In the first experiment, the student measured the initial rate of the reaction at five different concentrations of bromate(V) ions, . In each case, the initial concentrations of bromide ions and hydrogen ions were constant and in large excess. The results obtained are shown.
Initial concentration of bromate(V) ions / mol dm–3 |
Initial rate of reaction / mol dm–3 s–1 |
0.030 | 4.17 × 10–7 |
0.060 | 8.34 × 10–7 |
0.090 | 1.25 × 10–6 |
0.120 | 1.67 × 10–6 |
0.150 | 2.09 × 10–6 |
In the second experiment, the student determined the initial rates of the same reaction starting with different concentrations of the reactants.
Run | [] / mol dm–3 |
[Br–] / mol dm–3 |
[H+] / mol dm–3 |
Initial rate of reaction / mol dm–3 s–1 |
1 | 0.062 | 0.21 | 0.40 | 1.52 × 10–5 |
2 | 0.31 | 0.21 | 0.20 | 1.90 × 10–5 |
3 | 0.062 | 0.63 | 0.40 | 4.56 × 10–5 |
(2)
H+ ions.................................................................................................................
(1)
(3)
The presence of bromate(V) ions in drinking water is harmful to humans.
Bromate(V) ions can be converted to less harmful bromide ions by passing the water through palladium with a reducing agent.
Describe how a heterogeneous catalyst, such as palladium, increases the rate of a reaction.
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