Thermodynamics
Nine topics on the energy of chemical change. Endothermic and exothermic processes and their energy diagrams, how heat transfers to thermal equilibrium, calorimetry and the energy of phase changes, the enthalpy of reaction, and three ways to find it: bond enthalpies, formation enthalpies, and Hess’s law.
Topics
Equations For every problem in this unit
Sign convention
endothermic ΔH > 0 (absorbs); exothermic ΔH < 0 (releases)
Calorimetry
q = mcΔT (mass × specific heat × temperature change)
Thermal equilibrium
heat flows warm → cool until temperatures are equal
Enthalpy of reaction
ΔH = heat at constant pressure; scales with amount
Phase-change plateau
energy breaks intermolecular forces at constant temperature
Fusion vs vaporization
boiling costs more energy than melting
Bond enthalpies
ΔH ≈ bonds broken − bonds formed (breaking costs energy)
Formation
ΔH = ΣΔHf(products) − ΣΔHf(reactants); elements = 0
Hess's law
ΔH is a state function; sum steps (reverse flips sign, scale multiplies)
Unit 1 tools
Challenge bank
60 open-ended problems.
Read the question, work it out, then flip the card to compare your reasoning to the worked solution. Mark each card so you can return to the ones that still bite.
Question
Tap card to reveal explanation
Worked solution
Tap card to return to question
Nothing here yet.
Switch to All, work through some cards, and tag them as Got it or Revisit.
Cumulative assessment
Test the unit.
Twenty mixed items pulled from across all 9 topics. Identifies which misconceptions still bite when you cannot see which topic the question came from.
20questions
9topics
17codes covered