Hydrogen has its triple point at 13.8 K and 7.04 kPa. The normal (at 101.325 kPa) melting and boiling temperatures are 14.05 K and 20.28 K. Its critical temperature and pressure are 32.98 K and 1293 kPa. With these values, sketch (axes not necessarily to scale) the phase diagram for hydrogen. At 101.325 kPa, does hydrogen have a stable liquid state?

Which of the following diagrams depicts the distinction between the phase boundaries of a pure solvent and a solution?

A.

B.

C.

Consider the diagram below showing the vapor pressure curves for two solutions with equivalent concentrations. Solution A contains a nonvolatile solute while Solution B contains a volatile solute with a vapor pressure of around half of the vapor pressure of the pure solvent at a certain temperature.

Approximate the vapor-pressure curve for the pure solvent and determine its normal boiling point.

At standard pressure, iodine (I₂) has a melting point of 113.7°C and a boiling point of 184.3°C. Its liquid phase has a density of 3.96 g/cm³ and its solid phase has a density of 4.93 g/cm³. Its critical temperature and pressure are 546°C and 115 atm while its triple point is at 114°C and 0.12 atm. Starting from a point at 75°C and 5.0 atm the following changes were made:

Step 1: The temperature is increased to 200°C at a constant pressure.

Step 2: The pressure is decreased to 0.500 atm at a constant temperature.

Step 3: The temperature is decreased to 115°C at a constant pressure.

Step 4: The pressure is decreased to 0.050 atm at a constant temperature.

Identify the starting phase and final phases of I₂.

Which label is not correct for the phase diagram of a nonliquid crystalline substance?