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Rates, equilibrium and pH

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Question 1

Nitrogen monoxide and hydrogen react at high temperatures according to the following equation:

2NO(g)+2H2(g)→N2(g)+2H2O(g) 2\text{NO}(\text{g}) + 2\text{H}_2(\text{g}) \rightarrow \text{N}_2(\text{g}) + 2\text{H}_2\text{O}(\text{g}) 2NO(g)+2H2​(g)→N2​(g)+2H2​O(g)
a.

Explain how increasing the temperature increases the rate of this reaction. In your answer, describe what a labelled sketch using Boltzmann distributions would show (stating the labels for both axes and how the distribution curve changes with a temperature increase).

[5]
b.

The rate of this reaction is investigated by carrying out three experiments at a constant temperature. The results are shown in the table below:

Experiment[NO(g)] / mol dm−3[\text{NO}(\text{g})] \ / \ \text{mol dm}^{-3}[NO(g)] / mol dm−3[H2(g)] / mol dm−3[\text{H}_2(\text{g})] \ / \ \text{mol dm}^{-3}[H2​(g)] / mol dm−3Initial rate  / mol dm−3s−1\ / \ \text{mol dm}^{-3}\text{s}^{-1} / mol dm−3s−1
12.50 × 10-33.00 × 10-34.50 × 10-4
25.00 × 10-33.00 × 10-31.80 × 10-3
31.00 × 10-29.00 × 10-32.16 × 10-2

Determine the orders with respect to NO\text{NO}NO and H2\text{H}_2H2​, the rate equation, and the value of the rate constant, kkk, including its units. Explain your reasoning.

[5]
c.

Nitrogen dioxide and ozone react according to the following equation:

2NO2(g)+O3(g)→N2O5(g)+O2(g) 2\text{NO}_2(\text{g}) + \text{O}_3(\text{g}) \rightarrow \text{N}_2\text{O}_5(\text{g}) + \text{O}_2(\text{g}) 2NO2​(g)+O3​(g)→N2​O5​(g)+O2​(g)

The rate equation for this reaction is:

rate=k[NO2(g)][O3(g)] \text{rate} = k[\text{NO}_2(\text{g})][\text{O}_3(\text{g})] rate=k[NO2​(g)][O3​(g)]

Suggest a possible two-step mechanism for this reaction, where the first step is much slower than the second step.

[3]

Rates, equilibrium and pH Questions

  1. A Level
  2. /Chemistry
  3. /Rates, equilibrium and pH