States of Matter & Gas Laws — 60 Terms Defined

Absolute Zero States of Matter & Gas Laws K The lowest possible temperature, at which particles retain only their irreducible quantum zero-point motion. 0 K = −273.15 °C

Amorphous Solid States of Matter & Gas Laws Dimensionless A solid whose particles lack long-range order, showing only the short-range regularity characteristic of a frozen liquid.

Anisotropy States of Matter & Gas Laws Dimensionless The dependence of a physical property on the direction in which it is measured.

Average Kinetic Energy States of Matter & Gas Laws J The mean translational kinetic energy of the particles in a sample, dependent only on absolute temperature. KE = (3/2)kT per molecule

Avogadro's Law States of Matter & Gas Laws L/mol Equal volumes of all gases at the same temperature and pressure contain equal numbers of molecules. V ∝ n

Body-Centred Cubic States of Matter & Gas Laws Dimensionless A cubic arrangement with particles at the eight corners plus one at the centre of the cell. 2 atoms per cell, 68% packing

Boiling Point States of Matter & Gas Laws °C The temperature at which the vapour pressure of a liquid equals the external pressure acting on it. p_vap = p_external

Boyle's Law States of Matter & Gas Laws Pa·m³ At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure. p₁V₁ = p₂V₂

Capillary Action States of Matter & Gas Laws m The spontaneous rise or fall of a liquid in a narrow tube, driven by the balance between adhesion and cohesion. h = 2γcosθ / ρgr

Charles's Law States of Matter & Gas Laws m³/K At constant pressure, the volume of a fixed mass of gas is directly proportional to its absolute temperature. V₁ / T₁ = V₂ / T₂

Combined Gas Law States of Matter & Gas Laws Various The relation linking pressure, volume and temperature for a fixed amount of gas undergoing a change of state. p₁V₁ / T₁ = p₂V₂ / T₂

Compressibility Factor States of Matter & Gas Laws Dimensionless The ratio of the actual molar volume of a gas to that predicted by the ideal gas law. Z = pV / nRT

Condensation States of Matter & Gas Laws kJ/mol The change of a substance from the gaseous to the liquid state, accompanied by the release of latent heat.

Critical Point States of Matter & Gas Laws K, Pa The unique combination of temperature and pressure at which the liquid and gas phases of a substance become indistinguishable. (T_c, p_c)

Critical Temperature States of Matter & Gas Laws K The temperature above which a gas cannot be liquefied by pressure alone, however great. T_c = 8a / 27Rb

Crystal Defect States of Matter & Gas Laws Dimensionless Any irregularity that interrupts the perfectly ordered arrangement of particles in a crystal.

Crystalline Solid States of Matter & Gas Laws Dimensionless A solid in which the constituent particles are arranged in a regular, repeating three-dimensional pattern extending over long distances.

Dalton's Law of Partial Pressures States of Matter & Gas Laws Pa The total pressure of a gas mixture equals the sum of the pressures each component would exert alone in the same volume. p_total = p₁ + p₂ + p₃ …

Deposition States of Matter & Gas Laws kJ/mol The direct conversion of a vapour into a solid without an intermediate liquid phase.

Diffusion States of Matter & Gas Laws m²/s The spontaneous spreading of one substance through another as a result of random molecular motion. J = −D (dc/dx)

Effusion States of Matter & Gas Laws mol/s The escape of gas molecules one at a time through a hole much smaller than the mean free path. rate ∝ 1 / √M

Evaporation States of Matter & Gas Laws kJ/mol The escape of molecules from the surface of a liquid into the vapour phase below the boiling point.

Face-Centred Cubic States of Matter & Gas Laws Dimensionless A cubic arrangement with particles at the eight corners and at the centre of each of the six faces. 4 atoms per cell, 74% packing

Freezing Point States of Matter & Gas Laws °C The temperature at which a liquid becomes a solid, numerically identical to the melting point of the pure substance. ΔT_f = K_f × m