Chemical Engineering Thermodynamics
From PVT behaviour and property relations to phase equilibria and reaction equilibria.
Systems, properties, and the First Law
Thermodynamics begins by defining what you are studying (the system) and what surrounds it (the surroundings). Every subsequent calculation is anchored to this choice. The First Law — conservation of energy — governs all energy exchanges between a system and its surroundings, whether as heat or work.
The system is the region of space chosen for analysis. Everything outside is the surroundings. The boundary separates them and may be real or imaginary, fixed or moving.
Mass cannot cross the boundary, but energy (as heat Q or work W) can. A sealed piston-cylinder is a closed system. The system mass is fixed, so mole/mass balances are trivial. CN2104 Week 1 starts here.
Fluid streams enter and leave. Turbines, pumps, heat exchangers, and nozzles are all open systems analysed as steady-state control volumes. The steady-state energy balance introduces shaft work Ws and enthalpy H in place of internal energy U.
Neither mass nor energy crosses the boundary. Useful as a conceptual limit: the universe as a whole is isolated. Total energy and total entropy of an isolated system are constant and can only increase, respectively.
State functions (U, H, S, G, A) depend only on the current thermodynamic state, not how you got there. Path functions (heat Q and work W) depend on the process path. This distinction drives the power of the thermodynamic property framework.
Q1.Applying the Gibbs Phase Rule F = C − P + 2 to a single-component (C=1), two-phase (P=2) system at equilibrium gives F =