Question

phase diagram
pressure (atmospheres)
2.00
1.75
1.50
1.25
1.00
0.75
0.50
0.25
0.00
-200 -100 0 100 200 300 400 500 600 700 800 900
temperature (degrees c)
part a
at 0.50 atm, which phase change can occur?
a freezing
b condensation
c sublimation
d melting
part b
at 500 c, which phase change can occur?
a freezing
b deposition
c boiling
d melting
part c
at 1.5 atm and 400c, the substance is...

Explanation:

Part A

To determine the phase change at 0.50 atm, we analyze the phase diagram. Sublimation is the transition from solid to gas, which can occur at low pressures (like 0.50 atm) when temperature conditions allow. Freezing (liquid to solid), condensation (gas to liquid), and melting (solid to liquid) typically require different pressure - temperature relationships that don't align with 0.50 atm as well as sublimation in this context.

At 500°C, we look at the phase diagram. Boiling is the transition from liquid to gas, and at 500°C, the pressure - temperature conditions are suitable for boiling. Freezing (liquid to solid) occurs at lower temperatures, deposition (gas to solid) is not typical at 500°C, and melting (solid to liquid) also has different temperature - pressure requirements that don't match 500°C as well as boiling.

Answer:

C. Sublimation

Part B