Zadanie 1c
The final step can be summarized as: 3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g) ΔH⊖ = −138 kJ mol−1 (i) Sketch an energy profile for the overall reaction, indicating ΔH⊖ and the activation energy. (ii) Describe the…
- Materiał graficzny
Activation energy and Maxwell-Boltzmann curves
Define activation energy as the minimum energy for a successful collision, sketch Maxwell-Boltzmann energy distribution curves at two temperatures with correct axes and shape, and use the area beyond Ea to explain why rate rises steeply with temperature.
Tę umiejętność sprawdza 27 zadań wzorowanych na arkuszach IB z lat 2022–2026.
Zadania sprawdzające tę umiejętność: 27 Otwórz w wyszukiwarce z filtrami
Zadanie 2b
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…
- Materiał graficzny
Zadanie 3c
Pentan-2-ol can form by reacting pent-1-ene with water in the presence of an acid catalyst. CH2=CHCH2CH2CH3(g) + H2O(l) → CH3CH(OH)CH2CH2CH3(aq) ΔH⊖ = −84 kJ mol−1 (i) The first step of the mechanism for the formation of…
- Materiał graficzny
Zadanie 3c
Sodium reacts vigorously with water. (i) Write an equation, with state symbols, for the reaction of sodium with water. (ii) Describe one observation from the reaction in (i). (iii) Sketch, on the axes below, an energy profile for this reaction. Label the…
- Materiał graficzny
Zadanie 4d
Propene can be reduced to propane by hydrogen gas in the presence of a platinum catalyst at 50 °C. Outline how the catalyst increases the rate of this reaction.
Zadanie 23
What is the effect of decreasing temperature on this Maxwell-Boltzmann energy distribution curve? A. The curve maximum is higher and to the left of A. B. The curve maximum is lower and to the right of A. C. The curve maximum is higher and to the right of A. D.…
- Materiał graficzny
Zadanie 27
Which statements describe the activation energy of a reaction? I. The minimum energy that colliding particles must have in order to react II. The energy difference between the reactants and the transition state on an energy profile III. The energy difference…
Zadanie 3b
In moist air carbonyl dibromide is slowly hydrolyzed: Br2CO(g) + H2O(g) → CO2(g) + 2 HBr(g) (i) Suggest a method of monitoring the progress of this reaction at constant temperature so that its rate can be determined. (ii) Outline two reasons why a…
- Materiał graficzny
Zadanie 8b
Explain, using collision theory, why the rate of this reaction decreases when the temperature is lowered.
Zadanie 28
The Maxwell–Boltzmann distribution below was obtained for a sample of gas at temperature T1. The activation energy of a reaction is marked as Ea. Which graph shows the distribution for the same sample at a higher temperature, T2, together…
- Materiał graficzny
Zadanie 3f
(i) Sketch the Maxwell–Boltzmann energy distribution curve for the particles in this reaction mixture at 25 °C, marking on the diagram the activation energy both with and without the catalyst. (ii) On the same axes, sketch and label a second Maxwell–Boltzmann…
- Materiał graficzny
Zadanie 3c
(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…
- Materiał graficzny
Zadanie 28
Which reaction has the lowest activation energy? A. HBr(g) → H(g) + Br(g) B. 2 Cl(g) → Cl2(g) C. CH4(g) + Cl(g) → CH3(g) + HCl(g) D. HBr(g) → H+(g) + Br−(g)
Zadanie 26
In the energy profile of a reaction shown below, P, Q and R are energies measured from the same baseline. Which expressions give the activation energy of the forward reaction, Ea, and the enthalpy change of the forward reaction, ΔH? A. Ea = Q;…
- Materiał graficzny
Zadanie 27
Raising the temperature of a reaction mixture by 10 °C can double the rate of reaction, even though the collision frequency increases by only a few per cent. What is the main reason for the large increase in rate? A. The activation energy of the reaction is…
Zadanie 3c
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.
- Materiał graficzny
Zadanie 5c
Propenal can be made by the dehydration of propane-1,2,3-triol (glycerol). CH2(OH)CH(OH)CH2OH(l) → CH2=CHCHO(g) + 2 H2O(g) (i) Calculate the standard enthalpy change of this reaction, using ΔHf⊖ of propenal(g)…
Zadanie 6b
Explain, in terms of collision theory, why raising the temperature of the reaction mixture from 20 °C to 30 °C increases the rate of the reaction between D+ and OH−.
Zadanie 20
Two gases react very slowly even at 900 K and a high pressure. Which best explains the low rate of reaction? A. The frequency of collisions between the molecules is low B. A high fraction of the collisions has the correct orientation C. The reaction is…
Zadanie 4d
Sulfuryl chloride, SO2Cl2, is made industrially from sulfur dioxide and chlorine in the presence of an activated carbon catalyst. SO2(g) + Cl2(g) ⇌ SO2Cl2(g) ΔH⊖ < 0 (i) Sketch a potential energy profile for the forward reaction,…
- Tabela do uzupełnienia
Zadanie 17
Two samples of the same gas, at temperatures T1 and T2 where T2 > T1, have the Maxwell–Boltzmann distributions of kinetic energy shown. Which diagram is correct? A. Diagram A B. Diagram B C. Diagram C D. Diagram D
- Materiał graficzny
Zadanie 2e
The oxidation of sulfur dioxide in industry requires a catalyst. (i) State how a catalyst increases the rate of this reaction. (ii) Sketch a Maxwell-Boltzmann distribution curve showing the activation energies with and without a catalyst. (iii) Suggest how the…
- Materiał graficzny
Zadanie 6b
Explain how a catalyst such as manganese(IV) oxide increases the rate of this reaction.
Zadanie 21
The temperature of a reaction mixture is raised and the rate constant, k, increases. Which statement best explains why? A. The activation energy of the reaction decreases B. The reaction becomes more exothermic C. More particles are present in the same…
Zadanie 16
Which expression gives the enthalpy change, ΔH, of the forward reaction shown in the enthalpy profile? A. II − I B. I − II C. I − III D. III − II
- Materiał graficzny
Zadanie 19
How does a catalyst increase the rate of a reaction? A. It increases the average kinetic energy of the colliding particles. B. It lowers the activation energy so that a greater proportion of collisions are successful. C. It makes the reaction more exothermic.…
Zadanie 6b
(i) On the axes below, sketch Maxwell–Boltzmann energy distribution curves for the methanol molecules at two temperatures, T1 and T2, where T2 > T1. (ii) Explain the effect of increasing the temperature on the equilibrium yield of methanal.
- Materiał graficzny