Question

The number of independent intensive variables that need to be specified to determine the thermodynamic state of a ternary mixture at vapor-liquid-liquid equilibrium is:

• A. 0
• B. 1
• C. 2
• D. 3

Hint:

Remember, the phase rule provides a quick way to determine the number of variables required to define a system’s state in thermodynamics, especially useful in complex phase equilibrium problems.

Answer 1

The Correct Option is C

Step 1: Apply the phase rule.
The phase rule in thermodynamics is given by: \[ F = C - P + 2 \] where \(F\) is the number of degrees of freedom, \(C\) is the number of components, and \(P\) is the number of phases. 
Step 2: Identify the components and phases.
For a ternary mixture at vapor-liquid-liquid equilibrium:
\(C = 3\) (ternary mixture implies three components),
\(P = 3\) (one vapor phase and two distinct liquid phases).
Step 3: Calculate the degrees of freedom.
Substituting the values into the phase rule: \[ F = 3 - 3 + 2 = 2 \] Thus, two independent intensive variables need to be specified to fully describe the system.