Practice Hess’s Law (5.4) - Unit 5: Energetics and Thermochemistry

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6 sample questions

Question 1.
Define Hess's Law.
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Consider how enthalpy relates to the path of a reaction.
Question 2.
What is a state function?
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Think about properties like temperature or pressure.
3Question 3.
What does Hess's Law state?
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Think about the relationship between path and state.
4Question 4.
When applying Hess's Law, should the enthalpy change sign when a reaction is reversed?
- True
- False
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Consider what happens to energy in reverse reactions.
Question 5.
Determine the overall enthalpy change for a reaction given two pathways: A → B (ΔH = -45 kJ) and B → C (ΔH = +30 kJ). What is the enthalpy change for A → C?
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Focus on adding the enthalpies of the path taken.
Question 6.
Using Hess's Law, if the enthalpy changes for C to D is +50 kJ, and D to E is +30 kJ, what is the total for C to E if the path is reversed?
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Remember to flip the signs of any reversed processes.

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