Systems and state functions, the first law with one stated sign convention, the seven named enthalpies, Hess cycles and bond enthalpies, entropy, and ΔG = ΔH − TΔS with its four cases.
Unit 1 carries 17 of the 50 chemistry marks; with fourteen chapters sharing them, this one averages a little over one (MEC publishes weights by unit, not by chapter). Thermodynamics is the other heavy chapter of Physical chemistry alongside Electrochemistry, and it is the one that explains the rest: why a reaction happens at all, where the equilibrium constant of Chemical equilibrium comes from, and what the emf of a cell is measuring.
The MEC scope line runs: Systems and surroundings — open, closed and isolated; state of a system and state functions; internal energy, exothermic and endothermic processes, extensive and intensive properties; thermodynamic processes and the first law; enthalpy of reaction, solution, formation, combustion, neutralisation, fusion and vaporisation; Laplace's law and Hess's law; spontaneous and non-spontaneous processes, entropy and the second law; Gibbs free energy, prediction of spontaneity and its relation to the equilibrium constant; related numerical problems. The headings below are its points, in MEC's order.
Upgrade to unlock this and every premium study note, formula sheet and high-yield summary — plus unlimited mocks and full solutions.
See the plansMole Concept & Stoichiometry Made Simple
Avogadro's number, molar mass, molarity and the calculations that show up every year.
Basic Concepts in Chemistry: Masses, Radicals and Formulae
The vocabulary every other chemistry chapter assumes: valency, the carbon-12 mass scale, the radical charges you must know cold, and the two routines that turn a percentage into a formula.
Stoichiometry: The Mole, the Limiting Reagent and Ten Numericals
Dalton's postulates and where they fail, the five laws of combination, Avogadro's law and its uses, and every mole calculation the paper can ask, worked step by step.
Atomic Structure: From Bohr's Orbit to the Quantum Orbital
Rutherford's nucleus and why it could not survive, Bohr's three formulae, the hydrogen spectrum, de Broglie and Heisenberg, and the four quantum numbers that build every configuration.