ChE 122 LE 2

• In a polytropic process, if k=1,  it’s an isothermal process (constant temperature).
• In a polytropic process, if k = γ (the adiabatic index), it’s an adiabatic process (no heat transfer).
• In a polytropic process, if k = 0, it’s an isobaric process (constant pressure).
• B^0 = 0.083 - 0.422/T_r^ 1.6
• B^1 = 0.139 - 0.172 / T_r ^ 4.2
• Ideal-gas-state heat capacities increase smoothly with increasing temperature
• The state postulate

  The state of a simple compressible system is completely specified by two independent, intensive properties
• gibbs phase rule

  F = 2 - pi + N
• degrees of freedom of the system is given by the phase rule of J. Willard Gibbs
• Pure Substance - a substance that has a fixed chemical composition throughout (the mixture is homogeneous)
• SUBCOOLED LIQUID: A substance that is not about to vaporize.
• SATURATED LIQUID: A liquid that is about to vaporize
• SATURATED LIQUID-VAPOR MIXTURE: The liquid & vapor is at equilibrium
• SATURATED VAPOR: A vapor that is about to condense
• SUPERHEATED VAPOR: A vapor that is not about to condense
• That is, the temperature at which water starts boiling depends on the pressure; therefore, if the pressure is fixed, so is the boiling temperature.
• At a given pressure, the temperature at which a pure substance changes phase is called the saturation temperature Tsat.
• Likewise, at a given temperature, the pressure at which a pure substance changes phase is called the saturation pressure Psat.
• a substance at higher pressures boils at higher temperatures (Tsat increases with Psat)
• Critical point is the point at which the saturated liquid and saturated vapor states are identical.