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CHM 101 CHM 101 Past Questions Objective Question
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Question

Which statement is true for the combustion of ethanol? C₂H₅OH (l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l) with ΔH = -1370 kJ
Options
A The enthalpy change would be the same if gaseous water were produced.
B The enthalpy of the products is lower than the potential energy of the reactants.
C The products occupy a smaller volume than the reactants.
Correct Answer
D The reaction is endothermic.
Correct Answer

Option C is the correct answer.

Detailed Explanation

Comparing the moles of gas: reactants have 3 moles of gas (O₂), products have 2 moles of gas (CO₂). Thus, the products occupy a smaller volume. ΔH is negative, so the reaction is exothermic, meaning the products have lower enthalpy. If H₂O(g) were produced, the enthalpy change would be less negative because energy is required to vaporize the water.

Hint

Count the moles of gaseous reactants and products and consider the sign of ΔH.

Question Info

Course: CHM 101
Topic: CHM 101 Past Questions
Type: Objective
Difficulty: Not specified
Question 976 of 1872
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