Predict and explain, using collision theory, how concentration, pressure, surface area, temperature and a catalyst change the rate of a reaction, separating the effect of more frequent collisions from the effect of more energetic collisions.
Tę umiejętność sprawdza 29 zadań wzorowanych na arkuszach IB z lat 2022–2026.
The graph shows the maximum rate of decrease in light intensity for each run, plotted against temperature. (i) Draw the best-fit curve on the graph. (ii) Suggest two possible conclusions that can be drawn from the investigation.
An ‘iodine clock’ experiment can be based on two reactions that occur at the same time. S2O82−(aq) + 2 I−(aq) → 2 SO42−(aq) + I2(aq) slow 2 S2O32−(aq) + I2(aq) → S4O62−(aq) + 2 I−(aq) fast The iodine formed in the slow reaction is removed at…
The oxidation of sulfur dioxide to sulfur trioxide is an equilibrium reaction. 2 SO2(g) + O2(g) ⇌ 2 SO3(g) (i) State the equilibrium constant expression, K, for the reaction. (ii) Explain, with a reason, how compressing the gas mixture at constant…
Which of these changes will increase the time taken for this reaction to go to completion? Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g) A. Increase the temperature B. Increase the concentration of H2SO4 C. Use powdered zinc instead of zinc granules D.…
Which changes would make the initial rate higher when 50 cm3 of 1.0 mol dm−3 hydrochloric acid reacts with excess marble chips? CaCO3(s) + 2 HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g) I. Raising the temperature by 10 K II. Using 100 cm3 of 1.0 mol…
The rate of the reaction can be followed by measuring the volume of carbon dioxide collected as time passes. The graph shows the results obtained at 20 °C. Sketch, on the same axes, the curve you would expect if the experiment were repeated with the acid at a…
Which changes increase the rate of the reaction? CaCO3(s) + 2 HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g) I. Grinding the calcium carbonate into a fine powder II. Using a larger volume of hydrochloric acid of the same concentration III. Warming the…
(i) Sketch the Maxwell–Boltzmann energy distribution curve for the particles in this reaction mixture. Label the activation energy with and without the catalyst on the diagram. (ii) On the same axes, sketch and label a second Maxwell–Boltzmann curve for this…
(i) Sketch the Maxwell–Boltzmann distribution curve for 298 K on the same axes as the 800 K curve. (ii) On the graph, annotate the position corresponding to the activation energy, Ea. (iii) With reference to the graph, explain why a lower…
Which changes would increase the rate of the reaction between nitrogen and hydrogen? N2(g) + 3 H2(g) → 2 NH3(g) I. Lowering the temperature of the gas mixture II. Compressing the gas mixture into a smaller volume at constant temperature III. Adding an…
The dotted line shows the volume of hydrogen produced when an excess of magnesium ribbon is added to 50 cm3 of 2.0 mol dm−3 hydrochloric acid. Which curve shows the volume of hydrogen produced when the same excess of magnesium ribbon…
Identify two controlled variables in this investigation.
The rate of the reaction between hydrogen and iodine vapour increases markedly when the temperature is raised from 500 K to 550 K. What is the main reason for this increase? A. The activation energy of the reaction is lowered. B. Molecules collide more…
The student hypothesized, from theory, that doubling the mass of CuO would double the rate of the catalysed reaction. (i) Suggest why it is important to state a hypothesis before an experiment is carried out. (ii) Explain how collision theory could…
Explain why a higher temperature speeds up this reaction, with the help of annotations that you add to the Maxwell-Boltzmann distribution below, which is drawn for a temperature T1.
The student then followed the reaction with a spectrophotometer, which records the light absorbed by the mixture and so gives the concentration of the dye throughout the reaction. The graph shows [D+] against time for experiment 3. (i) Use the graph to…
Which change would decrease the rate of the reaction between zinc and dilute sulfuric acid? Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g) A. increasing the temperature of the acid from 20 °C to 30 °C B. grinding the zinc…
Excess zinc granules react with 40.0 cm3 of hydrochloric acid of concentration 1.00 mol dm−3 at 25 °C. The volume of hydrogen collected was measured over time and curve I was obtained. The experiment is repeated at the same…
(i) Bronze, an alloy of copper and tin, is used for ship propellers and bearings. Explain, by referring to its structure, why bronze is less malleable than pure copper. (ii) In a separate process, zinc is removed from a copper-zinc alloy by reaction with…
An excess of calcium carbonate lumps was added to a beaker of dilute hydrochloric acid, HCl(aq). Carbon dioxide escapes from the beaker, so the mass of the beaker and its contents was recorded against time to give curve 1. Which change could give curve…
Curve X (dashed) shows the volume of oxygen formed when 25 cm3 of 1.0 mol dm−3 hydrogen peroxide solution decomposes in the presence of a manganese(IV) oxide catalyst at 25 °C. 2 H2O2(aq) → O2(g) + 2 H2O(l) Which change would…
Ultraviolet (UV) light is being investigated as a way of killing micro-organisms in juice without heating it, so that less vitamin C is lost. The absorption spectrum of a dilute aqueous solution of sorbic acid, a preservative that is added to some bottled…
UV-C irradiation is an alternative to heat treatment that causes less loss of nutrients. The absorption spectrum of a solution of vitamin C is shown. (i) Deduce the type of electromagnetic radiation absorbed by vitamin C. Use section 5 of the data booklet.…
The reaction is usually carried out at a high temperature in the presence of a catalyst. (i) On the axes provided, sketch the energy profile of the reaction for the uncatalysed and for the catalysed pathway, and show ΔH and the activation energies.…
The conversion of carbon dioxide to methanol is usually carried out over a catalyst containing copper and zinc oxide. (i) Sketch energy profiles for the forward reaction, with and without the catalyst, on the axes shown. Label ΔH and the two activation…
Excess calcium carbonate reacts with 25 cm3 of hydrochloric acid of concentration 1.0 mol dm−3 in an open flask. The solid line shows how the decrease in mass of the flask and its contents changes with time. The experiment is…
Why does a powdered solid react faster with a dilute acid, at the same temperature, than a single lump of the same mass of the solid? A. Collisions between particles are more frequent. B. Collisions between particles are more energetic. C. The activation…
A student compares the rate of the reaction between magnesium ribbon and dilute hydrochloric acid at different temperatures by timing how long it takes for a piece of ribbon to dissolve completely. Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g) Suggest two…
Marble chips react with dilute hydrochloric acid. Which combination of changes would decrease the rate of reaction? A. Concentration of acid increased; marble chips replaced by larger chips B. Concentration of acid decreased; marble chips replaced by larger…
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