Adsorption Terms:

• Adsorption: Accumulation of adsorbate molecules at the surface of the adsorbent
• Adsorbent: The solid (or liquid) on whose surface adsorption occurs (e.g., activated charcoal)
• Adsorbate: The gas/liquid that gets adsorbed (e.g., $N_{2}$ gas, organic vapor)
• Adsorption isotherm: Relationship between amount adsorbed $\frac{x}{m}$ and pressure P at constant temperature
• Desorption: Reverse of adsorption — adsorbate molecules leave the surface

Colloid Terms:

• Colloidal dispersion: Heterogeneous system with particle size 1–1000 nm
• Dispersed phase: The substance divided into small particles (distributed)
• Dispersion medium: The continuous medium in which particles are dispersed
• Lyophilic: Solvent-loving colloid (stable, reversible, self-stabilizing)
• Lyophobic: Solvent-hating colloid (unstable, irreversible, needs stabilizer)
• Critical Micelle Concentration (CMC): Minimum concentration at which micelles form
• Kraft temperature: Minimum temperature at which micelles form
• Peptization: Converting freshly prepared precipitate into colloidal particles using an electrolyte
• Zeta potential: Electrokinetic potential at slipping plane; measure of colloidal stability
• Gold number: mg of protective colloid per 10 mL gold sol protected; lower = better protection
• Tyndall effect: Scattering of light by colloidal particles; distinguishes colloid from true solution
• Coagulation value / flocculation value: Minimum electrolyte concentration to cause coagulation

Catalysis Terms:

• Catalyst: Substance that increases reaction rate without being consumed
• Homogeneous catalysis: Catalyst and reactants in same phase
• Heterogeneous catalysis: Catalyst and reactants in different phases
• Active sites: Specific sites on catalyst surface where chemisorption and reaction occur
• Promoter: Substance that enhances catalyst activity (not itself a catalyst)
• Catalyst poison: Substance that reduces/destroys catalyst activity
• Enzyme: Biological catalyst (protein); follows lock-and-key model with Michaelis-Menten kinetics
• Inhibitor (competitive): Binds to active site, blocks substrate; overcome by excess substrate
• Inhibitor (non-competitive): Binds to allosteric site, changes enzyme shape; not overcome by excess substrate