Formalizing Enthalpy and Thermochemical Equations: Walkthrough

Section role: supports the formalization of student findings from the cold pack and hand warmer challenge into rigorous thermodynamic language while the teacher leads a whole-class debrief. Slides: (1) Title — 'Formalizing Enthalpy: From Lab Data to Theory'; (2) Defining Enthalpy Change — equation ΔH = H(products) minus H(reactants) at constant pressure; (3) Exothermic Profiles — diagram showing release of heat, negative ΔH, and stability; (4) Endothermic Profiles — diagram showing absorption of positive ΔH; (5) The Activation Energy Barrier — labeling Ea and transition state on reaction profiles; (6) Writing Thermochemical Equations — step-by-step example with C + O2 -> CO2 + 393.5 kJ; (7) Common Misconceptions — clarifying why a hot hand warmer means the system lost enthalpy to surroundings; (8) Molecular Visualization — previewing bond breaking (absorbing energy) versus bond forming (releasing energy). Closing slide: 'How does the sign of ΔH tell us where the energy belongs in a chemical equation?' — hands control back to the teacher to verify understanding before the mastery check.

Lara from Teachy