Core process

Chemical Engineering Thermodynamics

5 self-contained study topics — notes, diagrams, formulas, and worked examples for exams and GATE.

Topics

Properties of Pure Fluids
The state of a pure fluid is fixed by two independent intensive properties; from these you obtain all others through equations of state and the fundamental property relations, using the compressibility factor Z to correct the ideal-gas law for real behaviour.
Phase Equilibria
At equilibrium the fugacity of each species is equal in every phase; for vapour–liquid systems this reduces to modified Raoult’s law, y_iP = x_iγ_iP_i^sat, from which bubble points, dew points and K-values follow.
$Raoult: \gamma_{i} = 1 for ideal solution$
Equation of State
Equations of state relate P, V and T for real fluids; cubic forms like van der Waals and Peng-Robinson add a volume-correction b and an attraction term a fitted to critical properties, giving Z and fugacity where the ideal-gas law fails.
Fugacity and Activity
Fugacity is an effective pressure that makes the ideal-gas free-energy expression valid for real fluids; activity is its liquid-phase analogue. Equilibrium is stated as equal component fugacities, computed from fugacity coefficients φ (vapour) and activity coefficients γ (liquid).
$At equilibrium f_{i}^L = f_{i}^V for each component$
Thermodynamics of Solutions
Solution thermodynamics describes mixtures through partial molar properties and an excess Gibbs energy G_ex, whose composition derivative gives activity coefficients; an ideal solution has G_ex = 0, ΔH_mix = 0 and only entropic mixing.
$Ideal solution: \gamma_{i} = 1, \Delta H_{mix} = 0, \Delta S_{mix} = -R Σ x_{i} ln x_{i}$