Energy transfer and enthalpy
What students will learn
Track energy across a stated system boundary and use heat, phase and reaction ledgers to explain measured and calculated enthalpy changes.
Before this topic
- Moles, reacting proportions and limiting reactants
- Particle motion and interparticle interactions
- Temperature differences and units
Read and connect
Read: Endothermic and Exothermic Processes →
Choose the system boundary and explain heat-transfer signs without equating temperature with stored energy.
Read: Energy Diagrams →
Draw initial/final energy levels and a correctly signed change; a level diagram alone gives no reaction time.
Read: Heat Transfer and Thermal Equilibrium →
Explain thermal contact and a heat-capacity-weighted final temperature through energy conservation.
Read: Heat Capacity and Calorimetry →
Read a thermometer and build a heat balance including solution, cup and any external recipients.
Read: Energy of Phase Changes →
Account separately for warming/cooling and fixed-pressure phase-transition energy.
Read: Introduction to Enthalpy of Reaction →
Scale reaction heat with the balanced equation and distinguish reaction energy from the surroundings’ warming.
Read: Bond Enthalpies →
Count broken and formed bonds and state the gas-phase average-bond-enthalpy approximation.
Read: Enthalpy of Formation →
Use coefficient-weighted formation values with the correct phase and reference-state convention.
Read: Hess’s Law →
Construct a Hess accounting path by reversal, scaling and cancellation with energy conservation.
Supporting reading: Intramolecular Force and Potential Energy →
Revisit bond dissociation as energy input; bond length, energy and force have different meanings.
Supporting reading: Solids, Liquids, and Gases →
Revisit intact particles and changing phase arrangements when choosing heat-transfer terms.
Further study: Laws of Thermodynamics →
Further study: the original single-section thermodynamics overview, with accepted revisions; its heading does not establish comprehensive thermodynamics coverage.
Before this connection: Energy transfer and enthalpy; Entropy and standard free energy.
Check understanding
Use the complete prompt to make student reasoning visible, then consult the separate worked reasoning and criteria. A reading completion tick records reading history.
Read instruments and account for both heat recipients →
Estimate thermometer readings, calculate solution and cup heat, infer dissolution enthalpy, and justify precision and uncertainty.
Supplied instrument scales and data; no experiment is performed by completing this task.
Build and justify a Hess path →
Reverse and scale complete equations, show cancellation including phases, and connect the summed heat to energy conservation.
Standards and earlier reading lists
These topic placements organize reading. Edition-qualified Standards mappings and the existing complete unit task sets retain their reviewed scope.