Hess's law with formation and combustion data

Calculate the enthalpy change of a reaction with ΔH = sum of ΔHf(products) minus sum of ΔHf(reactants), or with ΔH = sum of ΔHc(reactants) minus sum of ΔHc(products), taking care with coefficients and the zero value for elements.

Zadania sprawdzające tę umiejętność: 6 Otwórz w wyszukiwarce z filtrami
Zadanie 8fPaper 2, maj 2025, TZ1
wzorowane6 pktobliczenioweśrednie (szac.)

trans-But-2-ene reacts with hydrogen in the presence of a nickel catalyst to form butane. CX4HX8(g)+HX2(g)CX4HX10(g)\ce{C4H8(g) + H2(g) -> C4H10(g)} (i) Calculate, in kJ, the enthalpy change of this reaction from the bond enthalpies in section 12 of the data booklet. (ii) Calculate,…

Zadanie 24Paper 1A, maj 2025, TZ1
wzorowane1 pktzamknięteśrednie (szac.)

The table shows standard enthalpies of combustion. Substance ΔHc\Delta H_\mathrm{c}^\ominus / kJmol1\mathrm{kJ\,mol^{-1}} CX4HX10(g)\ce{C4H10(g)} −2878 CX3HX6(g)\ce{C3H6(g)} −2058 CHX4(g)\ce{CH4(g)} −891 Which expression gives the enthalpy change, in kJmol1\mathrm{kJ\,mol^{-1}}, of the…

Zadanie 3dPaper 2, listopad 2025, TZ1
wzorowane15 pktobliczeniowetrudne (szac.)

(i) Calculate the enthalpy change, ΔH\Delta H, 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…

Zadanie 21Paper 1A, listopad 2025, TZ1
wzorowane1 pktzamknięteśrednie (szac.)

What is the enthalpy change, in kJmol1\mathrm{kJ\,mol^{-1}}, for the formation of methanol from carbon monoxide and hydrogen? CO(g)+2HX2(g)CHX3OH(l)\ce{CO(g) + 2H2(g) -> CH3OH(l)} Substance ΔHc\Delta H_\mathrm{c}^\ominus / kJmol1\mathrm{kJ\,mol^{-1}} CO(g)\ce{CO(g)} −283 HX2(g)\ce{H2(g)} −286…

Zadanie 5dPaper 2, specimen 2025
wzorowane9 pktobliczeniowetrudne (szac.)

Pentadecane can be cracked into smaller molecules. Consider the reaction: CX15HX32(g)3CX4HX8(g)+CX3HX8(g)\ce{C15H32(g) -> 3C4H8(g) + C3H8(g)} where CX4HX8\ce{C4H8} is but-1-ene. (i) Use the bond enthalpies in section 12 of the data booklet to determine ΔH\Delta H^\ominus for this reaction.…

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