Chem. - Ch.13 Phase Changes Review

Enthalpy of Fusion

The energy required to melt 1 gram of a substance at its melting point

Enthalpy of Vaporization

The energy required to vaporize 1 gram of a substance at its boiling point

Melting Point

The freezing point of a liquid is the same as the _____ of a solid for a particular substance

Vapor Pressure

The higher the temperature, the higher the _____ of a gas

Atmospheric Pressure

The lower the _____, the lower the boiling point

Critical Pressure

The only pressure which will cause a gas to liquefy at critical temperature

Phase Diagram

A graph of pressure versus temperature that shows in which phase a substance exists under different conditions of temperature and pressure

Boiling

A process which occurs when the vapor pressure of a liquid is equal to the atmospheric pressure

⇌

A reaction at equilibrium is represented by _____

Melts

A solid _____ when the patterned arrangement of the solid breaks down

Decrease

An increase in vapor pressure causes a _____ in volume

1. Heat energy disrupts hydrogen bonds 2. The amount of energy required depends on the strength of the bonds 3. The melting point is the temperature at which the forces holding its crystal lattice together are broken and it becomes a liquid 4. The melting point of amorphous substances may be unspecified

Describe the Process of Melting:

1. Many solids can become gases without first becoming a liquid 2. Some solids sublime at room temperature 3. The process of freeze drying is an example of sublimation

Describe the Process of Sublimation:

1. In liquid water, some particles have more energy 2. Particles that escape from liquid enter the gas phase 3. When vaporization occurs only at a surface it is called evaporation 4. The pressure exerted by a vapor over liquid is called vapor pressure 5. The temperature at which vapor pressure equals atmospheric pressure is called the boiling point

Describe the Process of Vaporization:

Throughout The Liquid

The difference between evaporation and boiling point is that evaporation occurs only on the surface of a liquid, while boiling occurs _____

Critical Point

For water, it is the point that indicates the critical pressure and critical temperature above which water cannot exist as a liquid (Water vapor will not change into a liquid)

Molasses, Glycerol

Give some examples of Nonvolatile Substances:

Rubbing Alcohol, Ether

Give some examples of Volatile Substances:

Le Chatelier's Principle

If stress is applied to a system of equilibrium, the system will tend to readjust so that the stress is reduced

Dynamic Equilibrium

In _____, molecules escape & return to the solid or liquid surface continuously, and at the same rate

Evaporation

Is when vaporization occurs only at the surface of a liquid

Liquid/Vapor Equilibrium

Liquid & Vapor phases coexist and Vaporization & Condensation occur on this line

Critical Temperature

Low _____ means there are weak forces between molecules

1. Deposition & Sublimation 2. Melting & Freezing 3. Vaporization & Condensation

Name 3 Opposing Processes:

Melting, Vaporization, Sublimation; Freezing, Condensation, Deposition

Name 3 Phase Transitions that are Gaining Energy; Name 3 that are Losing Energy

Dry Ice (Solid Carbon Dioxide), Moth Balls (Naphthalene), Solid Iodine

Name substances that Sublime:

Melting Point

Of a crystalline solid, this is the temperature at which the forces holding its crystal lattice together are broken and it becomes a liquid

Condensation

Phase Transition that involves "Gas to Liquid"

Deposition

Phase Transition that involves "Gas to Solid"

Vaporization

Phase Transition that involves "Liquid to Gas"

Freezing

Phase Transition that involves "Liquid to Solid"

Sublimation

Phase Transition that involves "Solid to Gas"

Melting

Phase Transition that involves "Solid to Liquid"

Condensation

Process by which a gas or vapor becomes of liquid

Vaporization

Process by which a liquid changes to a gas or vapor (Opposite of Condensation)

Sublimation

Process by which a solid changes directly to a gas without first becoming a liquid

Deposition

Process by which a substance changes from a gas or vapor to a solid without first becoming a liquid

Opposing Processes

Processes with a relationship where one is gaining energy and the other is losing energy

Solid/Liquid Equilibrium

Solid & Liquid phases coexist and Melting & Freezing occur on this line

Solid/Vapor Equilibrium

Solid & Vapor phases coexist and Sublimation & Deposition occur on this line

Volatile Substance

Substances that boil at a low temperature and evaporate quickly at room temperature

Nonvolatile Substances

Substances that evaporate slowly at room temperature and have a high boiling point

Lower Melting Points

Substances with Weak Intermolecular Forces have _____ than substances with Strong Intermolecular Forces

Strong Intermolecular Forces; Weak Intermolecular Forces

Substances with low vapor pressure have _____; And those with high vapor pressure have _____

Vapor

The _____ form of a substance is the gaseous form of a solid or a liquid at room temperature (25°C)

Triple Point

The point on a phase diagram that represents the temperature and pressure at which 3 phases of a substance can coexist

Liquefaction

The process of changing a gas to a liquid

Critical Temperature

The temperature above which no pressure will liquefy a gas

Freezing Point

The temperature at which a liquid is converted into a crystalline solid

Melting Point

The temperature when the vapor pressure for a solid equals the vapor pressure of a liquid

1. Cooling the temperature 2. Increasing the pressure

What are 2 ways to Liquefy a Gas?

101.325 kPa, 760 mmHg, 760 torr, 14.7 lb/in²(psi), 1.01325 Bar

[This is most likely given on Graphs] Name the Measurements for Standard Atmospheric Pressure (1 atm):

Ionic Compounds

_____ do not exert a significant vapor pressure because the inter-ionic forces are too strong to be overcome