OCR A Level Chemistry A
OCR A Level Chemistry A Enthalpy, Entropy and Free Energy Exam Questions
Free OCR A Level Chemistry A exam questions on Enthalpy, Entropy and Free Energy, with mark schemes. Covers lattice enthalpy, Born-Haber cycles, entropy and Gibbs free energy.
Enthalpy, Entropy and Free Energy exam questions
1 question pack of real past exam questions with its mark scheme. Answer every question without notes, then mark your answers line by line against the mark scheme.
StemUp mark scheme flashcards
OCR A Level Chemistry A H432 Flashcards (Anki & Quizlet)
Every answer is written in mark scheme wording, so you learn exactly what examiners give marks for. Use them on Anki or Quizlet, then test yourself with the questions on this page.
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About OCR A Level Chemistry A Enthalpy, Entropy and Free Energy
This topic covers energetics and feasibility.
What you need to know
- Lattice enthalpy Born-Haber cycles.
- Hydration Enthalpy of solution and hydration.
- Entropy ΔS calculations.
- Free energy ΔG = ΔH − TΔS.
Common mistakes in Enthalpy, Entropy and Free Energy
- Sign errors in Born-Haber cycles.
- Not converting J to kJ.
- Saying feasible means fast.
Try three Enthalpy, Entropy and Free Energy exam-style questions
1. State the condition for feasibility. (1 mark)
Show the mark scheme answer
ΔG ≤ 0.
2. Explain why entropy increases on melting. (1 mark)
Show the mark scheme answer
Particles become more disordered.
3. Explain how ionic charge affects lattice enthalpy. (1 mark)
Show the mark scheme answer
Higher charge gives stronger attraction and more exothermic lattice enthalpy.
Enthalpy, Entropy and Free Energy FAQs
What does this topic cover?
Lattice enthalpy, entropy and free energy.
How is the feasibility temperature found?
Set ΔG = 0, so T = ΔH/ΔS.
Why can endothermic reactions be feasible?
A large positive ΔS can make ΔG negative.
Revise this topic with flashcards: OCR A Level Chemistry A H432 Flashcards, with mark scheme answers for Anki and Quizlet.
