Practice Enthalpy Of Formation (δh_f°) (1.4.1) - Unit 5: Energetics and Thermochemistry

Practice: Enthalpy of Formation (ΔH_f°)

Lesson 1.4.1Unit 5: Energetics and Thermochemistry

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9 questions

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Exercise
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6 sample questions

Question 1.
What is the standard enthalpy of formation for elements in their standard state?
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Remember the definition of standard enthalpy of formation.
Question 2.
Write the reaction equation for the formation of water.
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Think of what elements combine to form water.
3Question 3.
What is the enthalpy of formation of elements in their standard state?
- 0 kJ/mol
- 100 kJ/mol
- Negative value
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Think about the baseline for enthalpy.
4Question 4.
Is the enthalpy of formation for water negative or positive?
- True
- False
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Recall what happens during process energy release.
Question 5.
Acetylene (C₂H₂) undergoes combustion to form CO₂ and H₂O. Given ΔH_f° is -1,203 kJ/mol for C₂H₂, -393.5 kJ/mol for CO₂, and -285.8 kJ/mol for H₂O, calculate the ΔH for the combustion reaction.
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Balance the reaction before plugging in enthalpy values.
Question 6.
Use Hess's law to find ΔH for the reaction 2NH₃(g) + 3O₂(g) → N₂(g) + 3H₂O(l). Given provided formation values, calculate and show steps.
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Break it down into multiple known reactions to build it out stepwise.

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