DE_Unit5_Phase Transitions_F2021

Water exists as a _____________ at 700 mmHg and 50 °C.

• solid
• liquid
• gas
• supercritical fluid

The pressure is increased on a sample of water at 0 °C from 0 mmHg to 800 mmHg.  In order, what changes occur?

• deposition, melting
• sublimation, melting
• condensation, freezing
• deposition, freezing

What is true regarding CO₂ for temperatures above 31 °C?

• It can never be liquified.
• It decomposes.
• It has a high pressure.
• It is a plasma.

What change occurs from F to E?

• sublimation
• deposition
• melting
• condensation

What is the normal boiling point of this substance?

• 150 °C
• 100 °C
• -50 °C
• 0 °C

Between which two points is Heat of Vaporization?

• A <----> B

• B <----> C

• C <----> D

• D <----> E

• E <----> F

Between which two points is the solid melting?

• A <---- B

• B <----> C

• C <---- D

• D <----> E

• E <---- F

What is the vapor pressure of water at 45°C. The normal boiling point (at 1atm) is 100°C and the ΔH_vap= 40.7 kJ/mol. R = 8.314 J/mol∙K

• 0.10 atm

• 2.27 atm

• 0.65 atm

• 0.061 atm

Estimate the enthalpy of vaporation for methane if the vapor pressure at 67°C is 362 atm and the normal boiling point is -161°C. R= 8.314 J/mol∙K

• 8.18 kJ/mol

• 26.5 kJ/mol

• 12.0 kJ/mol

• -33.5 kJ/mol

Between which points is the temperature of the substance remaining constant?

• A-B only. 
• A-B, C-D, E-F
• B-C only. 
• B-C, D-E