Sketch and interpret energy profile diagrams with reaction coordinate on the x axis and potential energy on the y axis, marking reactants, products, activation energy and ΔH, and link the relative stability of reactants and products to the sign of ΔH.
Tę umiejętność sprawdza 19 zadań wzorowanych na arkuszach IB z lat 2022–2026.
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…
Which classification is correct for this reaction? 2 Mg(s) + CO2(g) → 2 MgO(s) + C(s), heat is released A. Endothermic; temperature decreases; reactants more stable B. Exothermic; temperature decreases; products more stable C. Exothermic; temperature…
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…
The diagram shows the energy profile of a reaction. Which expression could give the enthalpy change, ΔH, of this reaction in kJ mol−1? A. +87 − 215 B. −215 + 87 C. +215 − 87 D. −215 − 87
Which of the following processes are exothermic? I. K(g) → K+(g) + e− II. H2O(g) → H2O(l) III. Ag+(g) + Cl−(g) → AgCl(s) A. I and II only B. I and III only C. II and III only D. I, II and III
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…
The energy profile below was recorded for a reaction. Which pair of statements is consistent with it? In each option the first statement compares the enthalpy of the products with that of the reactants and the second gives the sign of ΔH. A. products…
Which row correctly describes an endothermic reaction? A. The temperature of the surroundings rises and the products are more stable than the reactants. B. The temperature of the surroundings falls and the products are more stable than the reactants. C. The…
The potential energy profile of a reaction is shown. Which reaction has this energy profile? A. Cl2(g) → 2 Cl(g) B. CaCO3(s) → CaO(s) + CO2(g) C. N2O4(g) → 2 NO2(g) D. 2 Mg(s) + O2(g) → 2 MgO(s)
The enthalpy change of a reaction is ΔH = +58 kJ mol−1. Which statement about this reaction is correct? A. The reaction is endothermic and the products are less stable than the reactants. B. The reaction is endothermic and the products…
The diagram shows the energy profile of a reaction. P, Q and R are energies measured from the baseline of the potential energy axis. Which combination gives the activation energy of the forward reaction and the activation energy of the reverse reaction? A.…
(i) Draw the Lewis (electron dot) structure of carbonyl chloride. (ii) Mark the bond polarities on your Lewis structure using the symbols δ+ and δ−. (iii) Explain the shape of the carbonyl chloride molecule and whether it is polar. (iv) Outline…
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,…
Solid sodium hydroxide, NaOH, is dissolved in water and the temperature of the solution increases. Which diagram shows the enthalpy change for dissolving the solid in water? A. Diagram A B. Diagram B C. Diagram C D. Diagram D
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
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 diagram shows the enthalpy profile of an exothermic reaction. Arrows I, II and III show energy differences on the profile. Which expression gives ΔH for the forward reaction? A. II − I B. I − II C. I + II D. III − II
Ethane reacts with iodine vapour. C2H6(g) + I2(g) → C2H5I(g) + HI(g) (i) Calculate the enthalpy change of the reaction, ΔH, using section 12 of the data booklet. (ii) Draw and label an enthalpy level diagram for this reaction on the axes below.
The potential energy profile of a reaction is shown. Which statement correctly describes the reaction? A. Endothermic; the products have a lower potential energy than the reactants B. Endothermic; the products are less stable than the reactants C. Exothermic;…
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