🌡️ Phase Diagram
A phase diagram maps the thermodynamic conditions (pressure P and temperature T) under which phases of matter are stable. Phase boundaries are coexistence curves where two phases are in equilibrium. All three curves meet at the triple point — the unique (P,T) at which all three phases coexist. Above the critical point, liquid and gas become indistinguishable (supercritical fluid). Water has an anomalous negative-slope melting curve because ice is less dense than liquid water. 🇺🇦 Українська
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Key Phase Boundaries
Melting curve (solid-liquid) — governed by the Clausius-Clapeyron equation dP/dT = ΔS/ΔV. For water, ΔV<0 (ice contracts on melting), giving a negative slope — unusual among substances. Sublimation curve (solid-gas) — follows the Antoine equation log P ≈ A − B/T. Below the triple point, solid sublimes directly to vapour. Vapour pressure curve (liquid-gas) — ends at the critical point (Tc, Pc). Above Tc, there is no distinction between liquid and gas; supercritical CO₂ is widely used as a green solvent in extraction processes.