Practice question · Put in order
Arrange these phases and states in order of increasing molar entropy for the same substance.
- Solid just below its melting point
- Liquid just above its melting point
- Gas at its boiling point
- Perfect crystalline solid at 0 K
Hints
- The third law fixes the bottom of the scale.
- Each phase change upward adds freedom of arrangement.
Show the answer
- Perfect crystalline solid at 0 K
- Solid just below its melting point
- Liquid just above its melting point
- Gas at its boiling point
Why
A perfect crystal at 0 K has exactly. Warming adds vibrational freedom, melting adds translational freedom, and vaporising adds a very large amount more, which is why entropies of vaporisation dwarf entropies of fusion.
Practise Physical Equilibria and Phase Diagrams
The app has 5 more questions on this lesson, and keeps your place in the course. Chemistry I is free to start.
More questions on Physical Equilibria and Phase Diagrams
- Match each feature of a phase diagram to what it marks.
- A solid melts at 250 K with an enthalpy of fusion of 5.0 kJ/mol. Compute its entropy of fusion in J/mol/K.
- Vapour pressure depends purely on temperature, yet doubling the surface area of a liquid doubles the rate of…
- Why does water boil at a lower temperature at high altitude?
- Which statements about vapour pressure are correct?
- A liquid boils at 350 K with an enthalpy of vaporisation of 35 kJ/mol. Compute its entropy of vaporisation in…