Chemistry
Gases and acids–bases
Ideal gas, pH, and buffers.
Basics
Ideal gas
A model that ignores molecular volume and attractions. Real gases approach it at high T and low P. Partial pressure is proportional to mole fraction (Dalton).
Acids and bases
Brønsted–Lowry: acids donate H⁺, bases accept H⁺. For water, K_w = [H⁺][OH⁻] = 1.0×10⁻¹⁴ at 25 °C. Strong acids ionize essentially completely.
Buffer
A weak acid plus its conjugate base (or weak base plus conjugate acid) resists pH change. Henderson–Hasselbalch estimates pH.
Formulas
Ideal gas law
Links pressure, volume, amount, and temperature.
Symbols
-
Ppressure (Pa or atm) -
Vvolume (m³ or L) -
namount (mol) -
Rgas constant -
Tabsolute temperature (K)
pH
Negative log of hydrogen-ion concentration. 7 is neutral at 25 °C.
Symbols
-
[H⁺]hydrogen-ion concentration (mol/L)
Ion-product of water
If one ion rises, the other falls.
Symbols
-
[OH⁻]hydroxide concentration
Henderson–Hasselbalch
pH of a weak-acid buffer. If [A⁻]≈[HA], then pH≈pK_a.
Symbols
-
pK_a−log of the acid dissociation constant -
[HA]weak acid -
[A⁻]conjugate base
Key table
| R (L·atm) | 0.082057 L·atm·mol⁻¹·K⁻¹ |
|---|---|
| R (SI) | 8.314 J·mol⁻¹·K⁻¹ |
| Strong acids | HCl, HBr, HI, HNO₃, H₂SO₄ (first H), HClO₄ |
In this field
Atoms and the periodic table
Atomic structure, nucleus and electrons, periods and groups.
Chemical bonding
Ionic, covalent, and metallic bonds, plus molecular shape.
The mole and stoichiometry
Moles, molar mass, empirical formulas, and yield.
Thermo, equilibrium, kinetics
Enthalpy, Gibbs energy, K, and rate laws.
Electrochemistry and organic basics
Oxidation numbers, cells, Nernst, functional groups.
Nuclear chemistry
Radioactivity, half-life, binding energy.
Solutions and kinetics
Concentration, colligative properties, rate laws.
Analytical chemistry
Titration, spectroscopy, and chromatography — measuring what is present and how much.
Polymers and solids
Crystals and glasses, metal–ionic–covalent solids, polymer chains and the glass transition.
Coordination compounds
Ligands, coordination number, crystal field, colour, and an 18-electron sketch.
Electrochemical cells
Galvanic versus electrolytic, Nernst, Faraday, and a corrosion sketch.
Phase equilibria and diagrams
Gibbs phase rule, unary diagrams, eutectics, and the lever rule.