5 - Chapter Summary and Key Concepts
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Practice Questions
Test your understanding with targeted questions
What is the definition of enthalpy?
💡 Hint: Think about the relationship between heat and the energy of the system.
Describe what an exothermic reaction is.
💡 Hint: Consider the temperature changes in the surroundings during such reactions.
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Interactive Quizzes
Quick quizzes to reinforce your learning
What does a negative ΔH signify?
💡 Hint: Consider how temperature might change in the surroundings.
True or False: Hess's Law allows you to calculate reaction enthalpy regardless of the reaction pathway.
💡 Hint: Consider what Hess's Law helps in determining.
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Challenge Problems
Push your limits with advanced challenges
Determine the enthalpy change for the reaction 3 H₂(g) + N₂(g) → 2 NH₃(g) using standard enthalpy of formation values:
ΔH_f°[NH₃(g)] = –45.9 kJ/mol
ΔH_f°[H₂(g)] = 0
ΔH_f°[N₂(g)] = 0
💡 Hint: Think about how to apply the standard enthalpy of formation equation in practice.
Using bond enthalpies, estimate ΔH for the reaction:
C₂H₄(g) + H₂(g) → C₂H₆(g). Assume average bond enthalpies are:
C=C = 614 kJ/mol,
C–C = 347 kJ/mol,
C–H = 413 kJ/mol.
💡 Hint: Use average bond energies for the calculations involved.
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