(a)
Interpretation: The enthalpy change for the formation of 1 mole of a compound is to be calculated.
Concept Introduction: The standard enthalpy of formation is the amount of energy released or consumed when one mole of a substance is formed under standard conditions from its pure elements.
The standard enthalpy of formation of a pure substance in its elemental form or pure state is zero.
(a)
Answer to Problem 65A
The enthalpy change for the formation of 1 mole of aluminum oxide is
Explanation of Solution
The given
To get the required reaction of the formation of aluminum oxide, the reaction has to be reversed and thus, the sign of enthalpy change will also be reversed.
Now, to get the reaction of the formation of 1 mole of aluminum oxide, the reaction has to be multiplied by half and thus the value of enthalpy change will also be halved.
(b)
Interpretation: Whether the reaction is endothermic or exothermic is to be found.
Concept Introduction:
Endothermic reactions are the reactions in which heat is absorbed and thus the enthalpy change for the endothermic reaction is positive. Exothermic reactions are the reactions in which heat is released and thus, the enthalpy change for the exothermic reaction is negative.
(b)
Answer to Problem 65A
The reaction is exothermic.
Explanation of Solution
As the chemical reaction for the formation of 1 mole of aluminum oxide involves a negative sign of enthalpy change, it means the reaction is exothermic.
Chapter 17 Solutions
Chemistry 2012 Student Edition (hard Cover) Grade 11
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