Question

Like most substances, bromine exists in one of the threetypical phases. Br₂ has a normal melting point of -7.2⁰Cand a normal boiling point of 59C. The triple point foris and 40 torrs, and the critical point is and 100 atm. Using this information, sketch a phase diagram for bromine indicating the points described above. Based on your phase diagram, order the three phases from least dense to most dense. What are the stable phase of Br₂ at room temperature and 1 atm? Under what temperature conditions can liquid bromine never exist? What phase changes occur as the temperature of a sample of bromine at 0.10 atm is increased from$\mathbf{-}{\mathbf{50}}^0\mathbf{C}$ to ${\mathbf{200}}^0\mathbf{C}$ ?

Short answer

In this question, the phase diagram and density order of the phase of Br₂ and sample is shown in steps.

Step-by-step solution

Drawing the phase diagram of   Br2

Describing the order of phases from more dense to less dense

From the above phase diagram, the slope of solid-liquid phase equilibrium has a positive slope.

The density of phases in decreasing order of Br₂ at room temperature is given as

Solid > liquid > gas

Describing the temperature conditions can liquid bromine never exist

Above the critical point and below the triple point,${\mathrm{Br}}_2$ cannot exist in the liquid phase.

From the phase diagram, we can interpret that the temperature and pressure of the Br₂sample must be less than -7.3⁰C (triple temperature) and greater than 32⁰C(critical temperature). In this region, the Br₂ sample does not exist in the liquid phase.

Describing the phase changes that occur as the temperature of a sample of bromine at 0.10 atm is increased from -500Cto 2000C

The phase changes in the Br₂ sample when heated from -50⁰C to 200⁰C at 0.1 atm are demonstrated as

a. In the range of -50⁰C to -7.2C temperature, the phase will be the solid phase.

b. In the range of -7.2C to 59C temperature, the phase will be the liquid phase.

c. In the range of 59⁰C to 20⁰C temperature, the phase will be the gas phase.