Question

o Explain in your own words and without the use of jargon (a) the three ways of obtaining values of physical properties;

o (b) why some fluids are referred to as incompressible;

o (c) the “liquid volume additivity assumption” and the species for which it is most likely to be valid;

o (d) the term “equation of state”;

o (e) what it means to assume ideal gas behavior;

o (f) what it means to say that the specific volume of an ideal gas at standard temperature and pressure is 22.4 L/mol;

o (g) the meaning of partial pressure;

o (h) why volume fraction and mole fraction for ideal gases are identical;

o (i) what the compressibility factor, z, represents, and what its value indicates about the validity of the ideal gas equation of state;

o (j) why certain equations of state are referred to as cubic; and

o (k) the physical meaning of critical temperature and pressure (explain them in terms of what happens when a vapor either below or above its critical temperature is compressed). In addition, pick either a pure liquid or gas (i.e., ethanol, oxygen, eugenol, helium) that sparks your interest and provide some of its physical properties, its uses, and why you chose it. Enjoy!

Answer 1

The physical properties are those which can be observed or measured.Temperature,pressure,mass etc. Are all physical properties

Incompressible fluids are those fluids in which density does not change significantly with changes in pressure.

When liquid is assumed incompressible then the volume is additive and the expansion and contraction in volume is neglected.

Equation of state determines the relation between state variable under specified temp.,pressure etc.

Ideal gas behaviour states that the gas follows ideal gas law i.e. pv=nRT

Ideal gas law pv=nRT at standard conditions p= 1 atm, T=273 K and R= 8.314 J/K mol.

Partial pressure is the pressure exerted by a gas when present in a mixture of gas as if it occupied a volume equal to the volume of the mixture.

Molefraction and volume fraction The compressibility factor is used to make the correction in ideal gas behaviour so that it behaves like a real gas. Z=1 for ideal gas.Z<1 show volume less than ideal and Z>1 shows volume greater than ideal

Cubic equations of state have 3 roots for volume and compressibility. They are algebraic equations.

Critical temp. Is that temp above which the vapors cannot be liquified and critical pressure is the pressure required at critical temp to liquify a substance.