Apply Hess's law that the enthalpy change is independent of the route, and combine given equations (reversing, scaling and adding them) or construct an energy cycle to calculate the enthalpy change of a reaction that cannot be measured directly.
Tę umiejętność sprawdza 21 zadań wzorowanych na arkuszach IB z lat 2022–2026.
(i) Sulfur dioxide is oxidized to sulfur trioxide by nitrogen dioxide in the atmosphere. Determine the enthalpy change, ΔH⊖, in kJ mol−1, for the reaction SO2(g) + NO2(g) → SO3(g) + NO(g) given these reactions and enthalpy…
State the overall reaction of the cycle and determine its enthalpy change, in kJ mol−1.
Given the following data: CaO(s) + CO2(g) → CaCO3(s) ΔH = −p kJ 2 Ca(s) + O2(g) → 2 CaO(s) ΔH = −q kJ 2 CaCO3(s) → 2 Ca(s) + 2 C(s) + 3 O2(g) ΔH = +r kJ What is the ΔH of the…
(i) Calculate the enthalpy change, ΔH, for the overall synthesis of propyl ethanoate from propane and ethane shown above. Use section 12 of the data booklet. (ii) Two students each calculated the enthalpy change for the reaction between propan-1-ol and…
The standard enthalpy changes of two reactions are given below. N2(g) + O2(g) → 2 NO(g) ΔH⊖ = x kJ mol−1 2 NO(g) + O2(g) → 2 NO2(g) ΔH⊖ = y kJ mol−1 What is ΔH⊖, in…
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) Two related reactions were studied separately. Reaction 1:…
What is the enthalpy change of reaction, ΔH⊖ in kJ mol−1, for the partial hydrogenation of ethyne to ethene? C2H2(g) + H2(g) → C2H4(g) ΔH⊖ = ? C2H2(g) + 2 H2(g) → C2H6(g)…
Standard enthalpy changes of reaction are provided for the following reactions. C(s) + O2(g) → CO2(g) ΔH⊖ = −394 kJ…
Calcium reacts with water to form calcium hydroxide solution and hydrogen gas. Ca(s) + 2 H2O(l) → Ca(OH)2(aq) + H2(g) (i) Use the thermochemical equations in the table to calculate the enthalpy change, in kJ, when 8.00 g of calcium reacts completely…
Consider the following equations. H2(g) + Cl2(g) → 2 HCl(g) ΔH⊖ = −x kJ C(s) + 2 Cl2(g) → CCl4(g) ΔH⊖ = −y kJ 2 C(s) + H2(g) → C2H2(g) ΔH⊖ = +z kJ What…
Hydrogen sulfide, H2S, is removed from natural gas in the Claus process. Part of the hydrogen sulfide is burned in air to form sulfur dioxide, which then reacts with the remaining hydrogen sulfide to form sulfur. (i) Determine the enthalpy change, in…
What is ΔH, in kJ, for the following reaction? 2 CO(g) + 4 H2(g) → 2 CH3OH(l) Use the enthalpy changes of these reactions. A. +258 B. +314 C. -258 D. -3162
The enthalpy changes of two combustion reactions are ΔH⊖ = −549 kJ mol−1 ΔH⊖ = −518 kJ mol−1 Use…
The enthalpy changes of two reactions of the gases involved are known: ΔH1 = −548.8 kJ mol−1…
Which expression gives the value of ΔH⊖, in kJ, for the formation of one mole of NO2(g) from its elements, ? A. −180 + 114 B. 0.5 × (−180) + 0.5 × 114 C. 0.5 × 180 − 0.5 × 114 D. 0.5 × 180 + 0.5 × 114
Which calculation gives the standard enthalpy change of formation of nitrogen monoxide, in kJ, from the data below? A. (+66) + (−114) B. 0.5 × (+66) + 0.5 × (−114) C. (+66) − (−114) D. 0.5 × (+66) − 0.5 × (−114)
Whether a higher temperature favours the formation of methanol depends on the enthalpy change of the reaction CO(g) + 2 H2(g) → CH3OH(g) (i) Determine the enthalpy change, ΔH, for the production of methanol, in kJ, using bond enthalpies. Use…
The enthalpy changes of two reactions of nitrogen oxides are given. N2(g) + O2(g) → 2 NO(g) ΔH = +180 kJ 2 NO2(g) → 2 NO(g) + O2(g) ΔH = +114 kJ What is the enthalpy change, in kJ, of the following reaction?…
Which combination of ΔH1, ΔH2 and ΔH3 gives the enthalpy change of the reaction below? C2H5OH(l) + 3 O2(g) → 2 CO2(g) + 3 H2O(l) ΔH1: C(s) + O2(g) → CO2(g) ΔH2: …
Solid ammonium chloride decomposes when heated to form two gases, ammonia and hydrogen chloride. (i) Write the chemical equation for this decomposition. (ii) Calculate the volume of ammonia produced at STP when an 8.00 g sample of ammonium chloride decomposes.…
What is the enthalpy change of the reaction 2 C(s) + 3 H2(g) → C2H6(g), calculated from the enthalpy changes of the three reactions below? C(s) + O2(g) → CO2(g), ΔH = −394 kJ mol−1 ,…
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