CHEE2015 - Phase Equilibria of Pure Fluids

From the phase diagram of pure component, a non-condensable gas is found at

• Above the critical point.

• Below the critical point.

• On the critical point.

• On the equilibrium line.

Incorrect statement about a phase diagram of pure substance is

• Phase diagram are based on equilibrium conditions.

• Phase diagrams enable to view the properties of two or more phases as a function of temperature, pressure and other variables.

• For phase equilibrium, it is assumed that the phase remain invariant.

• The degree of freedom for liquid phase equals to 1.

If the vapour and liquid of a pure component are in equilibrium, the equilibrium pressure is called

• partial pressure.

• vapour pressure.

• liquid pressure.

• none of the mentioned.

Water will _______ on melting process and has the fusion curve with a _______ slope.

• contracts, negative

• contracts, positive

• expands, negative

• expands, positive

The vapor pressure of carbon tetrachloride (CCl₄) at 40.0 °C is found to be 213 mmHg and 836 mmHg at 80.0 °C. What is the enthalpy of vaporization in kJ/mol?

(R = 8.314 J/mole K)

• 31.4

• 3.14

• 0.314

• 314

The molar enthalpy of vaporization of hexane (C₆H₁₄) is 28.9 kJ/mol, and its normal boiling point is 68.73 °C. What is the vapor pressure of hexane at 25 °C?

(R = 8.314 J/mole K)

• 17.1 torr

• 760 torr

• 171 torr

• 780 torr

Below are the assumptions used in the Clausius - Clapeyron equation, except:

• Molar volume of liquid is much smaller than vapour.

• Vapour phase is an ideal gas.

• Heat of vapourization is independent of temperature.

• It only applicable for vapor pressure curve.

Find the incorrect statement about fugacity for pure component:

• The fugacity for a single-component ideal gas is equal to its pressure.

• Fugacity is an extensive variable, so it depends on the amount of the phase.

• The fugacity for a single-component liquid is equal to its saturation pressure if pressure is low enough that the gasphase is ideal.

• The fugacity of a liquid or solid does not change much as pressure increases.

What is the fugacity of water at 80^oC?

• 1 bar

• 0.4736 bar

• 4.736 bar

• 0.7011 bar

Which of the following increases the fugacity of a component A?

• Change phase (conversion) from solid to liquid.

• Change phase (conversion) from liquid to solid.

• Decreasing pressure.

• None of the mentioned.