KMT and Phase Change

Kinetic Molecular Theory

Review

The states of matter : All matter is composed of tiny particles that are always in motion. ​

​The Kinetic Molecular Theory​

Multiple Choice

The kinetic theory states

• Particles won't move if you don't apply energy to it.

• Particles only move in liquids and gases.

• Particles are always in motion.

• At the same temperature the object that has the most mass heats quicker.

1. ​Definition Shape

2. Definite Volume

3. Little movement

​

​Example:

ICE​

Solids

Multiple Choice

Solids are described as having a 

• definite shape and indefinite volume

• indefinite shape and indefinite volume

• definite shape and definite volume

• indefinite shape and definite volume

1. ​NO Definition Shape

   1. Takes the shape of the container.​

2. Definite Volume

3. Molecules have a "FLOW"

   1. Medium Kinetic Energy​

​

​Example:

Water

Liquids

Multiple Choice

Liquid has a definite ___________, but a variable _____________.

• shape, volume

• mass, area

• smell, taste

• volume, shape

Multiple Choice

To make a solid become a liquid, you must increase its________________.

• mass

• density

• kinetic energy

• potential energy

1. ​NO definition Shape

   1. Takes the shape of the container.​

2. NO definite Volume

   1. Fills the volume of the container​

3. Molecules move FAST and Random

   1. High Kinetic Energy​

​

​Example:

Steam

Gas

Change the TEMPERATURE!​

How do we move from one state to the next?

​High Kinetic Energy

​Low Kinetic Energy

Multiple Choice

The energy of an object as it is in motion is defined as

• Kinetic Theory

• Kinetic energy

• Potential energy

• Electric energy

Multiple Choice

In which state of matter are the particles moving the least random

• Gas

• Liquid

• Solid

• Plasma

Multiple Choice

In which state of matter are the particles only vibrating?

• Gas

• Liquid

• Solid

• Plasma

Multiple Choice

Of these three states of matter, which one has the most kinetic energy? 

• Solid 

• Liquid 

• Gas

Multiple Choice

As the _________________ of a gas increases, the kinetic energy of the particles increases. The particles move farther apart, and volume increases.

• speed

• height

• temperature

• area

Multiple Choice

Gases assume the volume and shape of their containers

• TRUE

• FALSE

Multiple Choice

State of matter that can fill containers with no fixed shape or volume.

• Solid state

• Liquid state

• Gas state

• Plasma state

Multiple Choice

State of matter in which materials have a definite shape and volume.

• Solid state

• Liquid state

• Gas state

• Plasma state

​Energy & Phase Changes

• Phase Change: the transformation from one state of matter to another

• Adding energy to a material increases the temperature of that material

  • At certain points, the temperature stops increasing​ while the substance changes state

    • Energy is used to either break or form intermolecular bonds

Experience Chemistry | Lesson 4.2

​Types of Phase Changes

• Some types of phase changes we experience on a daily basis

  • Solid → Liquid= Melting

  • Liquid → Solid= Freezing

  • Liquid → Gas= Vaporization

  • Gas → Liquid= Condensation

• Other types are less common in our everyday lives

  • Solid ​→Gas= Sublimation

  • Gas → Solid= Deposition

• The properties of a material can change at different states even if the particles are the same

Experience Chemistry | Lesson 4.2

​Heating a Liquid

• In the liquid state, particles have vibrational movement and rotational movement

  • still held together by intermolecular forces

• Heating a liquid adds energy to the particles, allowing them to break those forces holding them together and become a gas

• Boiling Point: the temperature at which intermolecular forces break in a liquid​

  • Can be predicted by looking at intermolecular forces

    • Stronger forces have higher boiling points

Experience Chemistry | Lesson 4.2

​Evaporation

• A liquid doesn't have to boil for vaporization to occur

• Below the boiling point, most particles do not have enough kinetic energy to vaporize into a gas, but a few do​

  • Every Particle has different energy levels

• Evaporation: The process by which particles at the surface of a liquid have enough energy to escape intermolecular forces​ and enter the gas phase

• Increasing the temperature can increase the evaporation rate, even if it is not raised to the boiling point

Experience Chemistry | Lesson 4.2

​Condensation

• In the process of condensation, some particles have a lower energy level, that allows them to enter the liquid phase

• Cooling the temperature reduces the energy or particles, which allows particles to return to a liquid state​

Experience Chemistry | Lesson 4.2

​Vapor Pressure

• When Liquid is in a container, some particles will evaporate

• When those particles collide with the wall of the container, it produces pressure on the container

• Vapor Pressure: the pressure of gas above a liquid​

  • Vapor pressure leads to a an equilibrium, where some particles evaporate while others condenses

Experience Chemistry | Lesson 4.2

​Vapor Pressure and Boiling

• Boiling point is the temperature of where the vapor pressure is equal to the external pressure on a fluid

• In a system of variable vapor pressure, different factors affect the boiling point of the liquid

  • Pressure: At sea level, warmer temperatures are needed to reach the boiling point

    • At higher altitudes with lower pressure, liquids boils at a lower temperature

    • At higher pressures, liquids boil at higher temperatures

Experience Chemistry | Lesson 4.2

​Heating a Solid

• particles in a solid gain vibrational energy

• With enough energy, the particles can no longer contain it, and break free from each other

  • As they break free, they change to a liquid phase

• Melting Point: the temperature at which a solid becomes a liquid

Experience Chemistry | Lesson 4.2

​Sublimation

• Solids generally melt into a liquid at a gradual temperature change

• In some cases, solids change to the vapor state without passing through the liquid phase

• Sublimation: The change from a solid to a gas state

  • Occurs at STP with substances that have extremely weak intermolecular bonds

  • Gives some solids vapor pressure

Experience Chemistry | Lesson 4.2

Match

Match the phase change to it's name

• Condensation

• Vaporization

• Melting

• Freezing

Gas → liquid

Liquid → Gas

Solid → Liquid

Liquid → Solid

• Gas → liquid

• Liquid → Gas

• Solid → Liquid

• Liquid → Solid

Multiple Choice

What state of matter would this substance be between points A & B?

• Solid

• Liquid

• Gas

Multiple Choice

What state of matter would this substance be between points C & D?

• Solid

• Liquid

• Gas

Multiple Choice

When does condensation occur?

• When liquid water changes into water vapour

• When water vapour changes into liquid water

Multiple Choice

The characteristic temperature at which a pure solid changes to a liquid is its __________ point.

• melting

• boiling

• Schaffer

• pressure

Phase Change Lab

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