Zadanie 4e
Ethene reacts with water in the presence of an acid catalyst at room temperature. C2H4(g) + H2O(l) → C2H5OH(l) ΔH⊖ = −44 kJ mol−1 (i) Calculate the change in entropy, ΔS⊖, for this reaction in…
Gibbs energy change calculations
Apply ΔG = ΔH - TΔS to calculate any of the four quantities, converting units consistently (ΔS in J per K per mol, ΔH in kJ per mol, T in kelvin) with thermodynamic data from the data booklet.
Tę umiejętność sprawdza 19 zadań wzorowanych na arkuszach IB z lat 2022–2026.
Zadania sprawdzające tę umiejętność: 19 Otwórz w wyszukiwarce z filtrami
Zadanie 4b
Propane undergoes complete combustion. C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l) (i) Calculate the standard enthalpy change of reaction, ΔH⊖, in kJ mol−1, for the combustion of propane. Use section 13 of the data booklet. (ii)…
Zadanie 5a
(i) Calculate, in kJ mol−1, the standard enthalpy change of this hydrogenation reaction using the enthalpy of combustion data in section 14 of the data booklet. (ii) The standard entropy change for this reaction is…
Zadanie 24
A reaction is spontaneous at low temperatures but becomes non-spontaneous when the temperature is raised. Which combination of signs of ΔH and ΔS is consistent with this behaviour? A. ΔH > 0 and ΔS > 0 B. ΔH < 0 and…
Zadanie 3d
(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…
- Materiał graficzny
Zadanie 3g
At 1200 K, calculate ΔG⊖ for the forward reaction and the value of the equilibrium constant, K. Use sections 1 and 2 of the data booklet. If you were unable to obtain an answer for 3f, use 230 J K−1, but this is not the correct…
Zadanie 3h
Determine the minimum temperature, in K, at which the forward reaction is spontaneous. Use section 1 of the data booklet. If you were unable to obtain an answer for 3f, use 230 J K−1, but this is not the correct value.
Zadanie 15
The decomposition of calcium carbonate is not spontaneous at low temperatures but is spontaneous at high temperatures. CaCO3(s) → CaO(s) + CO2(g) What are the signs of ΔH⊖ and ΔS⊖ for this reaction?…
Zadanie 30
For a reaction in a voltaic cell, both ΔH⊖ and ΔS⊖ are negative. Which statement is correct? ΔG⊖ = ΔH⊖ − TΔS⊖ and ΔG⊖ = −nFEcell⊖ A.…
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…
- Tabela do uzupełnienia
Zadanie 17
Which combination of the signs of ΔH⊖ and ΔS⊖ describes a reaction that is spontaneous only at low temperature? The options list the sign of ΔH⊖ first. A. positive, positive B. positive, negative C. negative,…
Zadanie 18
Which combination of signs of ΔH and ΔS belongs to a reaction that is not spontaneous at low temperatures but becomes spontaneous at high temperatures? A. ΔH positive and ΔS positive B. ΔH negative and ΔS…
Zadanie 18
A reaction is not spontaneous at low temperatures but becomes spontaneous when the temperature is raised sufficiently. What are the signs of ΔH and ΔS for the reaction? A. ΔH positive, ΔS positive B. ΔH negative, ΔS negative C. ΔH positive, ΔS…
Zadanie 3c
The standard free energy change, ΔG⊖, for the production of methanol is −44.0 kJ at 298 K and the standard enthalpy change, ΔH⊖, is −114 kJ. (i) State, with a reason, whether the production of methanol is spontaneous at 298 K.…
- Materiał graficzny
Zadanie 4d
Consider the formation of gaseous nitrogen dioxide from liquid dinitrogen tetroxide. N2O4(l) → 2 NO2(g) ΔH⊖ = +85.9 kJ mol−1 (i) Calculate the entropy change of the reaction, ΔS⊖, in…
- Tabela do uzupełnienia
Zadanie 15
Which row gives the signs of ΔH and ΔS for a reaction that is spontaneous at low temperatures but non-spontaneous at high temperatures? A. ΔH < 0, ΔS < 0 B. ΔH < 0, ΔS > 0 C. ΔH > 0, ΔS < 0 D.…
Zadanie 17
Dividing both sides of the equation ΔG⊖ = ΔH⊖ − TΔS⊖ by −T gives −ΔG⊖/T = −ΔH⊖/T + ΔS⊖. Which term represents the entropy change of the surroundings? A. −ΔG⊖/T…
Zadanie 1d
A student investigates the dissolution of ammonium chloride in water as the basis of an instant cold pack, in which solid ammonium chloride is kept apart from water by a thin membrane. The enthalpy change when one mole of solid ammonium chloride dissolves in…
Zadanie 17
A reaction has a negative ΔH and a negative ΔS. Which statement about the spontaneity of the reaction is correct? A. It is spontaneous at all temperatures B. It is spontaneous only at high temperatures C. It is spontaneous only at low…