AllChemicals — The Online Chemical Glossary | https://allchemicals.info/chemical/651-phase-diagram
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Quick Reference
Also Known As
Phase diagram, P-T diagram, state diagram, stability diagram
What is Phase Diagram?
A graph showing the physical states of a substance as a function of temperature and pressure. It contains regions for solid, liquid, and gas phases separated by boundary lines. The triple point is where all three phases coexist; the critical point is where liquid and gas become indistinguishable.
Properties & Characteristics
A phase diagram is a graph (usually pressure vs. temperature) that shows the stable state(s) of a substance or mixture under different conditions. Single-component phase diagrams show regions of solid, liquid, and gas, separated by phase boundaries. Key features: triple point (T_tp, P_tp: all three phases in equilibrium), critical point (T_c, P_c: liquid-vapour distinction disappears), and normal boiling/melting points (at 1 atm). The slopes of phase boundaries are determined by the Clausius-Clapeyron and Clapeyron equations.
Uses & Applications
Phase diagrams are used in: materials science (alloy phase diagrams guide heat treatment, solidification control), chemical engineering (design of distillation, extraction, crystallisation), supercritical fluid technology (CO₂ phase diagram guides SFE design), geology (mineral stability under crustal conditions), and food science (chocolate tempering uses the cocoa butter phase diagram).
Safety Information
Phase diagrams identify conditions where dangerous phase transitions occur: the ice-water-steam system explains steam explosions; CO₂ solid-gas transition explains dry ice handling (sublimation produces large volumes of CO₂ gas in confined spaces — asphyxiation hazard). Process engineers must design for all phases that may occur under operating conditions.
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
SynonymsPhase diagram, P-T diagram, state diagram, stability diagram
Frequently Asked Questions
A graph showing the physical states of a substance as a function of temperature and pressure. It contains regions for solid, liquid, and gas phases separated by boundary lines. The triple point is where all three phases coexist; the critical point is where liquid and gas become indistinguishable.
Phase diagrams are used in: materials science (alloy phase diagrams guide heat treatment, solidification control), chemical engineering (design of distillation, extraction, crystallisation), supercritical fluid technology (CO₂ phase diagram guides SFE design), geology (mineral stability under crusta…
Phase diagrams identify conditions where dangerous phase transitions occur: the ice-water-steam system explains steam explosions; CO₂ solid-gas transition explains dry ice handling (sublimation produces large volumes of CO₂ gas in confined spaces — asphyxiation hazard). Process engineers must design…
Editorial standards: Chemical data is sourced from peer-reviewed literature,
CAS Registry, NIST WebBook, and PubChem. Safety information reflects guidance from OSHA, ECHA,
and IAEA. For educational purposes only — always consult official SDS documentation and qualified
professionals before handling chemicals.
