The rate and extent of chemical change

A student investigated how concentration affects the rate of reaction between magnesium and hydrochloric acid. Figure 5 shows a gas syringe. What is the volume of gas in the syringe?

Which two variables should the student keep the same to make the investigation a fair test? Select two options.

Table 5 shows the student's results for the experiment with hydrochloric acid of a lower concentration. Calculate mean value X in Table 5. Do not include the anomalous result in your calculation. Give your answer to 2 significant figures.

Plot the data from Table 5 on Figure 6. You should include your answer to Question 07.3. You do not need to draw a line of best fit.

Figure 7 shows results of the experiment with the hydrochloric acid of a higher concentration. Calculate the mean rate of reaction between 0 and 50 seconds. Use Figure 7 and the equation: mean rate of reaction = mean volume of gas collected / time taken

Describe how the rate of reaction changes between 0 and 160 seconds. Use Figure 7.

The student concludes that the rate of reaction is greater when the concentration of hydrochloric acid is higher. Why is the rate of reaction greater when the concentration of hydrochloric acid is higher? Select two options.

Give the approximate temperature and pressure used in the reactor.

Water molecules break down into hydrogen ions and hydroxide ions. The equation for the reaction is: H₂O ⇌ H⁺ + OH⁻ Which sentence describes this reaction at equilibrium?

One stage in the industrial production of sulfuric acid is the reaction of sulfur dioxide with oxygen to produce sulfur trioxide. This reversible reaction reaches dynamic equilibrium. Figure 7 shows the percentage yield of sulfur trioxide in this reaction at different temperatures. Which statement about the forward reaction is correct? Use Figure 7.

The equation for the reaction is: 2SO₂(g) + O₂(g) ⇌ 2SO₃(g) Explain why the percentage yield of sulfur trioxide in this reaction is greater if the pressure is higher.

In industry, the reaction is done at 450 °C and atmospheric pressure. Under these conditions the yield of sulfur trioxide is 86%. Suggest two reasons why a higher pressure is not used.

This reaction uses a catalyst to increase the rate of the reaction. The catalyst is a metal oxide. Which is the most likely metal in the metal oxide catalyst? Use the periodic table.

A student investigated the rate of the reaction between zinc and sulfuric acid. The equation for the reaction is: Zn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂(g). Figure 10 shows the apparatus. The method used is: 1. Pour 50 cm³ of sulfuric acid into the conical flask. 2. Add excess zinc to the conical flask. 3. Insert the stopper and start a timer. 4. Measure the volume of hydrogen collected in the 50 cm³ measuring cylinder every 20 seconds for 180 seconds. Explain why the volume of hydrogen collected in the 50 cm³ measuring cylinder is less than the volume of hydrogen produced.

A different student investigated how the concentration of sulfuric acid affected the rate of the reaction. The student did a different experiment using sulfuric acid of concentration 0.40 mol/dm³. The student calculated the number of moles of hydrogen collected after every 20 seconds. Figure 12 shows the results. Determine the rate of reaction at 45 seconds. You should draw a tangent on Figure 12. Give your answer in standard form.

The student repeated the experiment using 0.20 mol/dm³ sulfuric acid instead of 0.40 mol/dm³ sulfuric acid. Excess zinc was used in each experiment. Sketch a line on Figure 13 to show the results you would expect.