4
QuizMultiple Choice

Enthalpy of Reaction

Question 4 • Foothill-B Period-Chemistry-26/27B

How should the enthalpy of an intermediate step be manipulated when used to produce an overall chemical equation?

Answer
A
Multiply the enthalpy by 1 if the chemical equation is reversed.
B
Multiply the enthalpy by –1 if the chemical equation is reversed.
C
Add 2 to the enthalpy if the coefficients must be doubled.
D
Add 2 to the enthalpy if the coefficients must be cut in half.

Explanation

When you reverse a chemical equation, the reaction proceeds in the opposite direction, so its enthalpy change changes sign. Therefore, multiply the enthalpy by −1. The correct choice is “Multiply the enthalpy by –1 if the chemical equation is reversed.”

AI-written and checked against the verified answer.

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