Midterm Solution

Problem 1

Describe the difference between a first order and a second order phase transition. Give examples of each type. (10 points)

When determining the type of phase transition you must look at the change in the physical quantities of the material. If the change is sudden, a discontinuity in the first derivative of the free energy, then you have a first order phase transition. Examples of this would be water going from a liquid state to a gaseous state. A second order phase transition is continuous in the first derivative of the free energy and displays discontinuity only in the second derivative. With this fact, second order phase transitions will experience spontaneous symmetry breaking. Examples of a second order phase transition includes ferromagnetism, antiferromagnetism, and superconductivity.