Question

For the chemical reaction Ca (s) + ½ O₂ (g) → CaO (s) ΔH° = -635 kJ/mol. What is the molar enthalpy (in kJ/mol) for the reaction 2 CaO (s) → 2 Ca (s) + O₂ (g)?

A) -635
B) 635
C) -1270
D) 1270

Answer 1

The molar enthalpy for the reaction 2 CaO (s) → 2 Ca (s) + O₂ (g) is 1270 kJ/mol.

Step-by-step explanation:

To find the molar enthalpy for the reaction 2 CaO (s) → 2 Ca (s) + O₂ (g), we can use the enthalpy change for the given reaction Ca (s) + ½ O₂ (g) → CaO (s), which is -635 kJ/mol. Since the given reaction is exothermic and the enthalpy change is negative, the enthalpy change for the reverse reaction is 635 kJ/mol. Now, for the reaction 2 CaO (s) → 2 Ca (s) + O₂ (g), which is double the given reaction, the molar enthalpy is double as well. Therefore, the molar enthalpy for the reaction 2 CaO (s) → 2 Ca (s) + O₂ (g) is 1270 kJ/mol (Choice D).