MCAT General Chemistry Review - Alexander Stone Macnow, MD 2019-2020

Thermochemistry
Equations to Remember

(7.1) First law of thermodynamics: ΔU = QW

(7.2) Heat transfer (no phase change): q = mcΔT

(7.3) Heat transfer (during phase change): q = mL

(7.4) Generalized enthalpy of reaction: ΔHrxn = HproductsHreactants

(7.5) Standard enthalpy of reaction: ΔH°rxn = Σ ΔH°f,products − Σ ΔH°f,reactants

(7.6) Bond enthalpy: ΔH°rxn = Σ ΔHbonds broken − Σ ΔHbonds formed = total energy absorbed − total energy released

(7.7) Entropy: Image

(7.8) Second law of thermodynamics: ΔSuniverse = ΔSsystem + ΔSsurroundings > 0

(7.9) Standard entropy of reaction: ΔS°rxn = Σ ΔS°f,products − Σ ΔS°f,reactants

(7.10) Gibbs free energy: ΔG = ΔHTΔS

(7.11) Standard Gibbs free energy of reaction: ΔG°rxn = Σ ΔG°f,products − Σ ΔG°f,reactants

(7.12) Standard Gibbs free energy from equilibrium constant: ΔG°rxn = —RT ln Keq

(7.13) Gibbs free energy from reaction quotient: Image