Unit 4 Section 3: Modeling Phase Changes

Unit 4 Section 3 Modeling Phase Change

Multiple Choice

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

• Phase Energy

• Kinetic energy
• Potential energy
• Electric energy

Multiple Choice

PSI, torr, mmHG, atm all are units for....

• temp

• vol

• pressure

• weather

Fill in the Blank

1,976 torr is how many atmospheres? (atm)

Multiple Choice

At higher temperatures

• particles in an object have less energy

• particles in an object have more energy

• a gas contracts

• a.     particles in an object break apart.

Multiple Choice

Which of the following states of matter has the LOWEST level of energy?

• Solid

• Liquid

• Gas

• Plasma

Multiple Choice

As the particles increase in movement, they begin to _____ and move faster.

• move closer

• spread out

Multiple Choice

Which type of solid has low melting points and covalently bonded atoms?

• Amorphous solids
• Ionic solids
• Molecular solids
• Metallic solids

Drag and Drop

​

Placeholder

are a type of covalent network solid that are made up of different physical forms of the same element.

Drag these tiles and drop them in the correct blank above

Allotropes

Molecules

Ionic compounds

Metals

Alloys

Polymers

Match

Match the description to the correct particle motion

• The particle moves around an axis

• The particle stays in one place while moving

• The particle moves in space

Rotation

Vibration

Translation

• Rotation

• Vibration

• Translation

Lesson Objectives

• Summarize how variations in kinetic energy among particles result in changes in state

• Relate Intermolecular forces to the energy needed to change states of matter.

• Differentiate between the properties of various types of solids

​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

​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

​Heating a Liquid

• In the liquid state, particles have vibrational 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​

  • Liquids turn into a gas both at the surface and within the liquid

  • Maintaining requires constant energy

  • Can be predicted by looking at intermolecular forces

    • Compounds with Stronger forces have higher boiling points

​Evaporation

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

• Every particle in a liquid has a different energy level

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

• 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

Evaporation

​Condensation

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

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

​Vapor Pressure

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

  • If those particles collide with the wall of the container, it produces pressure on the container that can cause them to condense back into a liquid

• Vapor Pressure: the pressure of gas above a liquid​ that leads to an equilibrium, where some particles evaporate while others condense, so overall the state does not change

​Vapor Pressure and Boiling

• The boiling point is the temperature at which the vapor pressure is equal to the external pressure on a fluid

• Changing the pressure on a liquid can change its boiling point

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

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

• At higher pressures, liquids boil at higher temperatures

  • Pressure cookers use vapor pressure to speed up cooking

    • Increasing the pressure increases the temperature to higher and higher point

Multiple Choice

TRUE OR FALSE: Matter can switch between the three phases of solid, liquid, and gas by gaining or losing energy as heat

• True
• False

Multiple Choice

Condensation is . . . .

• gas to liquid
• liquid to gas
• gas to solid
• solid to liquid

Multiple Choice

As the temperature of an object increases, the energy will increase at the exact same rate

• True

• False

Multiple Select

Select all that apply.

In the process of evaporation.....

• particles at the surface that have enough energy can escape the liquid and enter the gas phase.

• some of the molecules in a gas will have lower energy than the rest and can transition to the liquid phase

• it happens at the surface of liquids and its one type of vaporization

• increasing the temperature of a liquid results in more particles having enough energy to evaporate

Multiple Choice

True or False: Increasing the temperature of a liquid results in more particles having enough energy to evaporate

• False

• True

Multiple Choice

The change from Liquid to Gas is...

• Vaporization

• Condensation
• Freezing
• Melting

Melting & Freezing

• Particles in a solid have vibrational energy.

• With enough energy, the intermolecular forces between particles can no longer contain them, and they break free from each other and change to a liquid phase

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

• As you remove energy, the particles slow back down and return to the solid state.

• Freezing Point: The point at which a liquid chages into a solid.

​Sublimation

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

• If the temperature and/or pressure are too low for the liquid state to exist, 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

• Deposition: The change of state directly from a gas to a solid

• These changes give some solids' vapor pressure

​Phase Diagrams

• Phase Diagram: a graph that describes the conditions of temperature and pressure at which a substance exists as a solid, liquid, or gas

• Triple point: a point on a phase diagram where all three states of matter can exist in equilibrium with each other.

• Critical Point: a temperature or pressure at which a substance can not exist in the liquid state

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

Sublimation is the change of a

• Solid to a liquid

• Liquid to a solid

• Gas to a solid

• Solid to a Gas

• Gas to a Liquid

Multiple Choice

This image is called a

• Pressure map

• phase diagram

• transitional chart

• Melting table

Multiple Choice

Change of a gas directly into a solid

• Sublimation

• Condensation

• Evaporation

• Deposition

Multiple Choice

A gas...

• has a definite shape but no definite volume

• has a definite volume but no definite shape

• has fast-moving molecules

Multiple Choice

Which of the following terms identifies the change from a liquid to solid?

• Melting

• Condensation

• Vaporization

• Freezing