Question

Sketch a generic phase diagram for a substance that has a more dense solid phase than a liquid phase. Label all regions, lines, and points.

Short answer

Begin by drawing a set of axes, with pressure (P) on the vertical axis and temperature (T) on the horizontal axis. Draw a solid-liquid phase transition line with a negative slope, a liquid-gas phase transition curve that approaches the pressure axis, and a solid-gas phase transition line that intersects with the liquid-gas curve at the triple point. Label the regions as "Solid," "Liquid," or "Gas," and identify and label the triple point and critical point on the diagram.

Step-by-step solution

1. Draw axes for pressure and temperature

Begin by drawing a set of axes, with pressure (P) on the vertical axis and temperature (T) on the horizontal axis. Label each axis accordingly.

2. Draw the solid-liquid phase transition line

Draw a line with a negative slope in the low pressure and low temperature region, starting from the temperature axis. This represents the boundary between the solid and liquid phase. Label this line as "Solid-Liquid."

3. Draw the liquid-gas phase transition line

Starting from a point above the right end of the solid-liquid line, draw a curve that initially has a positive slope but goes through an inflection point and approaches, but does not reach, the pressure axis. This represents the transition from the liquid to the gas phase. Label this curve as "Liquid-Gas."

4. Draw the solid-gas phase transition line

Draw a line with a positive slope that begins at the temperature axis at a point to the right of where the solid-liquid line begins. This line should intersect the liquid-gas curve at a point called the "triple point." Label this line as "Solid-Gas."

5. Label the regions on the diagram

Label the regions formed by the intersecting lines as follows: - The region to the left of the solid-gas line and below the solid-liquid line is the "Solid" phase. - The region between the solid-liquid and the liquid-gas lines is the "Liquid" phase. - The region to the right of the liquid-gas line and above the solid-gas line is the "Gas" phase.

6. Identify and label the triple point

Locate the point where the solid-liquid, solid-gas, and liquid-gas lines all intersect. This is the "triple point," where all three phases can coexist at equilibrium. Label this point as "Triple Point."

7. Identify and label the critical point

Find the point on the liquid-gas curve where the slope changes from positive to negative. This is the "critical point," which represents the highest temperature and pressure at which gas and liquid phases can coexist. Label this point as "Critical Point." The completed phase diagram should have labeled axes, phase transition lines, and critical and triple points, as well as labeled regions for solid, liquid, and gas phases.