Unit 3: Chemistry - Thermal Energy and Air Pressure

Question 1

Do all the states of matter expand and contract when heated and cooled?

Answer 1

Liquid = expands and contracts
ex. thermometer
Gas = expands and contracts
ex. balloon
Solid = expand and contract
ex. metal ball + ring

Question 2

What is the special case for liquids?

Answer 2

Expands when freezes because water molecules expand and form rings with air in middle

Question 3

Thermal Energy

Answer 3

Motion of all particles, distance, and attractions of particles

Question 4

Heat

Answer 4

Transfer of thermal energy from warm to cool

Question 5

Conductor

Answer 5

Easily transfers heat –> something feels colder but is the same temperature, that is a conductor

Question 6

Insulator

Answer 6

Does not transfer heat easily
ex. glass

Question 7

How does air pressure affect a marshmallow in a syringe?

Answer 7

High Pressure System = when syringe compressed –> fewer space for gas particles to move –> makes marshmallow shrink
Low Pressure System = when syringe expand –> more space for gas particles to move –> makes marshmallow expand
*amount of particles does not change

Question 8

What happens to the pressure when the temperature increases?

Answer 8

Temperature increases = pressure increases because particles move faster

Question 9

What happens to the pressure when the volume increases?

Answer 9

Volume increases = pressure decreases because particles have more space to move

Question 10

What happens to the pressure when mass increases?

Answer 10

Mass increases = pressure increases because more particles –> more collisions

Question 11

Thermal Contraction

Answer 11

Decreased temperature = decreased volume = decreased kinetic energy

Question 12

Thermal Expansion

Answer 12

Increased temperature = increased volume = increased kinetic energy

Question 13

Pressure

Answer 13

Pressure = Pressure –> gravity “wins”
Outside pressure > pressure –> can hold liquid (straw holding water because air pressure presses again water)
Gravity = more pressure near ground

Question 14

When a bottle is placed in an ice bath, it compresses, but when a bottle is placed in hot water, it expands. Why does this happen?

Answer 14

Compresses because pressure from outside presses again bottle
Expands because pressure from bottle fights against pressure from outside

Question 15

When water reaches its boiling point, why does the temperature remain steady?

Answer 15

Water molecule’s energy is to overcoming bonds to phase change to gas –> little energy to increasing temperature

Question 16

Condense

Answer 16

Gas to liquid (removes energy)

Question 17

Vaporization

Answer 17

Liquid to gas (add energy)
1. Boiling - throughout
2. Evaporization - only at surface

Question 18

Melting

Answer 18

Solid to liquid (add energy)

Question 19

Imploding Can Experiment

How do you remove air from the can?

Answer 19

Water boil because added energy –> water vapors form + push gas out of can because can is not closed system –> can filled with water vapors

Question 20

Imploding Can Experiment

Why did the can implode?

Answer 20

No gas in can, so when put in cold water, air pressire inside can was low –> pressire from outside crushed can

Question 21

Imploding Can Experiment

Why were there so much water?

Answer 21

Air pressire from outside pushed water from bath into can because there was not gas in can –> space in can

Question 22

Deposition

Answer 22

Gas to SOLID (removes energy)

Question 23

Sublimation

Answer 23

Solid to GAS (adds energy)

Question 24

Dry ice

Answer 24

Carbon dioxide as solid
Good example of sublimation
Doesn’t wet anything

Question 25

What happened when you put dry ice into water?

Uncertain

Answer 25

Bubbles rise up = gas
CO2 reaches surface –> touches air –> decreases energy = water vapor

Uncertain

Question 26

Why did the balloon inflate with the dry ice in the beaker?

Answer 26

Sublimation of CO2 pushes and fills beaker –> balloon inflates