General Chemistry 2 — Quiz 2

What is a phase diagram?

• A graph that shows the phases of a system under different conditions

• A representation of chemical bonds in a molecule

• A diagram that depicts atomic structures

• A chart showing only temperature variations

What are the typical axes in a phase diagram?

• Volume and temperature

• Pressure and volume

• Pressure and temperature

• Temperature and time

What happens at the triple point of a substance?

• Solid turns directly into gas

• Solid, liquid, and gas phases coexist in equilibrium

• The critical temperature is reached

• The substance is only in the gas phase

Why does water’s solid-liquid phase line have a negative slope?

• Ice has a higher density than liquid water

• Ice has a lower density than liquid water

• Water does not expand upon freezing

• The boiling point of water is very high

At what temperature and pressure does water reach its critical point?

• 100°C and 1 atm

• 374°C and 22.064 MPa

• 0°C and 1 atm

• -78°C and 5.11 atm

What phase change occurs at the sublimation line?

• Solid to liquid

• Liquid to gas

• Solid to gas

• Gas to liquid

Which of the following best describes a supercritical fluid?

• A solid that cannot melt

• A state where liquid and gas phases are indistinguishable

• A substance at absolute zero

• A gas that behaves like a solid

Why is solid CO₂ called "dry ice"?

• It sublimates without forming a liquid

• It melts at a very high temperature

• It remains solid at room temperature

• It absorbs moisture from the air

At what pressure does CO₂'s triple point occur?

• 1 atm

• 5.11 atm

• 10 atm

• 0.01 atm

What phase changes occur when a system moves along the fusion curve?

• Liquid to gas

• Solid to liquid

• Gas to solid

• Liquid to vapor