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.
Catalysts and alternative reaction pathways
Explain how a catalyst provides an alternative pathway with lower activation energy, sketch energy profiles with and without a catalyst for exothermic and endothermic reactions, and show on a Maxwell-Boltzmann curve why more particles can react; enzymes are biological catalysts.
Tę umiejętność sprawdzają 22 zadania wzorowane na arkuszach IB z lat 2022–2026.
Zadania sprawdzające tę umiejętność: 22 Otwórz w wyszukiwarce z filtrami
Zadanie 15
Manganese(IV) oxide is added to a solution of hydrogen peroxide, which then decomposes much faster. Which quantity on the energy profile of the decomposition is the same with and without the catalyst? A. The activation energy of the forward reaction B. The…
Zadanie 2b
When potassium thiocyanate solution is added to a pale yellow solution containing iron(III) ions, the following equilibrium is established. [Fe(H2O)6]3+(aq) + SCN−(aq) ⇌ [Fe(SCN)(H2O)5]2+(aq) + H2O(l) [Fe(H2O)6]3+(aq) is pale yellow and…
- Materiał graficzny
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 4a
In the first step, manganese(III) ions formed from the manganate(VII) are complexed by ethanedioate ions. [Mn(H2O)6]3+(aq) + 2 C2O42−(aq) → [Mn(C2O4)2(H2O)2]−(aq) + 4 H2O(l) (i) Adding a small amount of manganese(II) sulfate, MnSO4(s), at the…
Zadanie 2b
(i) Oil of vitriol, spirit of hartshorn and wood alcohol are old trivial names still occasionally used for chemical substances, and names like these can be a source of confusion in international scientific communication. Outline how the modern system of naming…
- Materiał graficzny
Zadanie 3b
(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…
- Materiał graficzny
Zadanie 3b
The forward reaction is endothermic, uses platinum as a catalyst, and takes place at 800 K. Sketch the reaction's energy profile both with and without the catalyst present, labelling the activation energies and ΔH.
- Materiał graficzny
Zadanie 21
Which of the following correctly describes the effect of a catalyst on a reaction? A. It increases the frequency of collisions between reactant particles B. It increases the proportion of collisions with energy greater than or equal to the activation energy C.…
Zadanie 3d
The Maxwell-Boltzmann distribution for the uncatalysed reaction at temperature T1 is shown below. Add annotations to show how a catalyst changes the situation.
- Materiał graficzny
Zadanie 3d
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,…
Zadanie 2d
Sulfur trioxide is manufactured industrially by the oxidation of sulfur dioxide. 2 SO2(g) + O2(g) ⇌ 2 SO3(g) ΔH⊖ = −198.0 kJ mol−1 (i) Outline what is meant by dynamic equilibrium. (ii) Deduce the Kc expression for this…
- Materiał graficzny
Zadanie 6b
Explain how a catalyst such as manganese(IV) oxide increases the rate of this reaction.
Zadanie 16
The solid curve in the enthalpy profile below is for a reaction carried out under one set of conditions. The dashed curve is obtained when the same reaction is carried out with one change. Which change is represented by the dashed curve? A. A higher…
- Materiał graficzny
Zadanie 17
The potential energy profile of an exothermic reaction is shown. The vertical arrows I, II and III show three energy changes. Which energy changes would be affected by adding a catalyst? A. I and II only B. I and III only C. II and III only D. I, II and III
- Materiał graficzny
Zadanie 2e
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.…
- Materiał graficzny
Zadanie 2e
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…
- Materiał graficzny
Zadanie 17
Which statement correctly explains why a reaction is faster when a catalyst provides an alternative reaction pathway? A. It raises the average kinetic energy of the reacting particles. B. It lowers the activation energy, so a greater proportion of collisions…
Zadanie 17
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 2c
Methanol is manufactured from carbon monoxide and hydrogen. The reaction involves the equilibrium: CO(g) + 2 H2(g) ⇌ CH3OH(g) (i) Deduce the expression for the equilibrium constant, Kc, for this equation. (ii) Explain why an increase in pressure…
Zadanie 3a
Outline how the presence of the silver catalyst affects the rate of the reaction, and explain why.
Zadanie 2e
Compound P can be synthesized by reacting 4,6-dichloroquinazoline with another reactant, B. (i) Deduce the structure of B. (ii) The reaction can be catalysed by copper(I) iodide, CuI. State the ground-state electron configuration of the Cu+ ion.…
- Materiał graficzny