Chemical Engineering Thermodynamics II Assignment Help & Online Tutoring

Chemical Engineering Thermodynamics II usually covers solution thermodynamics, partial molar properties, chemical potential, fugacity and activity coefficients, vapour–liquid and liquid–liquid equilibrium, activity-coefficient models such as Margules, Van Laar and Wilson, and chemical reaction equilibria, including equilibrium constants, the effect of temperature and equilibrium conversion.

Fugacity is a corrected pressure that describes the escaping tendency of a component in a real system. For an ideal gas it equals the partial pressure. In real systems, the fugacity coefficient corrects for non-ideality. At phase equilibrium, the fugacity of each component is equal in every phase, which is the basis of phase equilibrium calculations.

An activity coefficient measures how far a component in a liquid mixture departs from ideal-solution behaviour. A value of one means ideal behaviour, a value above one means positive deviation, where molecules repel each other more than in the pure liquids, and a value below one means negative deviation. It appears in the modified Raoult's law.

Raoult's law states that the partial pressure of a component above an ideal liquid mixture equals its liquid mole fraction multiplied by its saturation pressure. Combined with Dalton's law, it gives yᵢP = xᵢPᵢˢᵃᵗ. It works well for similar molecules, such as benzene and toluene, at low pressure.

Raoult's law applies to a component present at high concentration, or to mixtures of similar substances, and uses the pure component's saturation pressure. Henry's law applies to a dilute solute, such as a gas dissolved in a liquid, and uses Henry's constant instead. In a dilute binary solution, the solvent follows Raoult's law and the solute follows Henry's law.

For a liquid of known composition at a given temperature, bubble-point pressure is the sum of each component's mole fraction multiplied by its saturation pressure, including activity coefficients if the mixture is non-ideal. Vapour mole fractions then follow from each component's contribution divided by the total pressure.

The bubble point is the temperature or pressure at which the first bubble of vapour forms from a liquid. The dew point is the temperature or pressure at which the first drop of liquid forms from a vapour. Between them, a mixture exists as two phases, which is the region used in flash calculations.

An azeotrope is a mixture whose vapour and liquid have the same composition at equilibrium, so it cannot be separated further by simple distillation. Positive deviations from Raoult's law can give minimum-boiling azeotropes, such as ethanol and water, while negative deviations can give maximum-boiling azeotropes.

The Gibbs–Duhem equation relates changes in the partial molar properties of components in a mixture at constant temperature and pressure. In phase equilibrium it is used to check the thermodynamic consistency of activity-coefficient data and to calculate one component's activity coefficient from the other's in a binary system.

The Margules equation is an activity-coefficient model that expresses ln γ as a function of composition. The two-suffix form, ln γ₁ = A x₂² and ln γ₂ = A x₁², suits simple, symmetric systems. The three-suffix form uses two parameters for asymmetric systems. Parameters are fitted from experimental VLE data.

The van 't Hoff equation shows that the natural log of the equilibrium constant changes with temperature in proportion to the standard enthalpy of reaction. For exothermic reactions, K falls as temperature rises, reducing equilibrium conversion. For endothermic reactions, K rises with temperature, so higher temperatures favour products.

Relative volatility compares how easily two components vaporise. It equals the ratio of their K-values, or y over x for each. For an ideal mixture it equals the ratio of saturation pressures. A value well above one makes separation by distillation easy, while a value near one makes it difficult and needs many stages.

Yes. Thermodynamics is a regular part of GATE Chemical Engineering, and questions often come from VLE calculations, fugacity, activity coefficients, partial molar properties and reaction equilibria. Practising numericals with careful units and iteration, rather than memorising formulas alone, gives the best results.

Yes. A chemical engineering tutor explains the derivations behind each equation, works through VLE, activity-coefficient and reaction-equilibrium numericals with you, and shows how to set up iterative calculations in Excel or Python. You solve the problems yourself, so you can handle university exams and GATE independently.