Measuring enthalpy changes

Chemia IBPaper 2, maj 2026, TZ1wzorowane4 pktotwarteśrednie (szac.)

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

Chemia IBPaper 1B, maj 2026, TZ2wzorowane2 pktobliczenioweśrednie (szac.)

Zadanie 2c

Calculate the specific energy of ethanol for trial 5, in J g⁻¹. Use sections 1 and 2 of the data booklet. $\text{specific energy} = \dfrac{Q}{m_{\mathrm{fuel}}}$ m_water = 120.0 g

• Materiał graficzny

Chemia IBPaper 1B, maj 2026, TZ2wzorowane2 pktotwartełatwe (szac.)

Zadanie 2f

Suggest two ways in which the error in this experiment could be reduced.

• Materiał graficzny

Chemia IBPaper 2, maj 2026, TZ2wzorowane5 pktotwarteśrednie (szac.)

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

Chemia IBPaper 2, maj 2026, TZ3wzorowane5 pktotwarteśrednie (szac.)

Zadanie 4f

Ethanol can be used as a fuel. (i) Calculate the enthalpy change for the combustion of ethanol using section 12 of the data booklet. C₂H₅OH(g) + 3 O₂(g) → 2 CO₂(g) + 3 H₂O(g) (ii) The enthalpy of formation of ethanol is defined from its elements. State,…

Chemia IBPaper 1A, maj 2026, TZ1wzorowane1 pktzamkniętełatwe (szac.)

Zadanie 19

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…

Chemia IBPaper 1A, maj 2026, TZ2wzorowane1 pktzamknięteśrednie (szac.)

Zadanie 19

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

Chemia IBPaper 1A, maj 2026, TZ3wzorowane1 pktzamknięteśrednie (szac.)

Zadanie 19

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

• Materiał graficzny

Chemia IBPaper 2, maj 2025, TZ2wzorowane11 pktobliczeniowetrudne (szac.)

Zadanie 1b

In aqueous solution hydrogen cyanide behaves as a weak acid. (i) Write an equation for the ionization of hydrogen cyanide in water. (ii) Outline two ways in which a solution of 0.050 mol dm⁻³ HCN could be distinguished experimentally from…

• Materiał graficzny

Chemia IBPaper 1B, maj 2025, TZ3wzorowane4 pktotwarteśrednie (szac.)

Zadanie 1b

The sealed vessel was left for the reaction to proceed. Suggest two properties of the system, other than its colour, that could be measured to follow the progress of the reaction over time, and predict how each would change as the forward reaction proceeds.