THERMAL ENERGY AND MATTER

Ch 16.1

True False Statement True False

Heat, which is the flow of thermal energy, always flows from cold

objects to hot objects

Absolute zero is a reference point using the Kelvin scale, used to

measure temperature

Thermal energy depends on mass, temperature and phases of the

object

An object will expand in hot temperatures, and shrink in colder

temperatures called thermal expansion/contraction

Specific heat is how much heat is needed to raise the temperature of an object, and is the same for all

objects

Work and Heat

Heat- transfer of thermal energy from 1 object to another due to temperature difference

Heat flows from hot objects to cold objects

Temperature

Temperature- measure of how hot or cold an object is compared to a reference point °C=

boiling/freezing point of water

Absolute zero- reference point in K, which is 0K

Temperature relates to the kinetic energy of particles hot= faster

particles cold= slower

particles

Thermal Energy

Depends on: Mass Temperature Phase- solid, liquid, gas

of an object

Thermal Contraction and Expansion

Thermal Expansion- increase volume due to temperature increase Particles move farther apart

Thermometers Increase temp. = alcohol moves/expands =

temperature you read

Specific Heat

Specific Heat- amount of heat needed to raise the temperature of 1g of material by 1°C

The lower the SH, the more the temp. rises when a given amount of energy is absorbed by a given mass

Specific Heat

Q = m c ΔT

Q- heat absorbed by material, J

M- mass, gC- specific heat, J/g°CΔT- change in temp. °C

Specific Heat Practice

An iron skillet has a mass of 500g. Its specific heat is 0.449 J/g°C. How much heat must be absorbed to raise the temperature by 95C?

Given:

Formula:

Solve:

Math Practice pg 477

2.

4.

3.

5.

Measuring Heat Changes

Calorimeter- sealed instrument used to measure changes in thermal energy

Uses principle that hot energy flows to cold, until they equal the same temperature.

HEAT AND THERMODYNAMICS

Ch. 16.2

True False Statement True False

Conduction transfers thermal energy when 2 objects touch

Convection transfers thermal energy through moving fluids

Radiation is the transfer of energy through space

The 1st law of thermodynamics state energy is not created or destroyed

The 3rd law of thermodynamics state you must reach absolute zero

Conduction

Transfer of thermal energy between 2 touching objects, with no overall transfer of matter

Slower in gases due to particles colliding less often

Conduction

Conducts thermal energy well

Can be hot or cold

Ex: Cu, Al Tile vs Wood

Conducts thermal energy poorly

Can be hot or cold

Ex: Air, plastic, wool

Thermal Conductors Thermal Insulators

Convection

Transfer of thermal energy when particles of a fluid move from 1 place to another Hot moves to cold

Convection Current- fluid circulates in a loop as it alternatively heats up and cools down Oven, heaters Naturally- ocean currents, weather, molten

rock

Radiation

Transfer of energy by waves moving through space Heat lamps

All objects radiate energy- as temperature increases the rate it radiates energy increases

Conduction, Convection or Radiation Heating?

Thermodynamics

Study of conversions between thermal energy and other forms of energy

James Joule, 1800’s

Energy is conserved

Thermodynamics1st Law of Thermodynamics

Thermodynamics

Thermal energy can flow from cold to hot objects ONLY if work is done to the system

Heat engine- device converts heat into work

Waste heat- thermal energy not converted into heat

Absolute zero cannot be reached

2nd Law of Thermodynamics4th Law of Thermodynamics

USING HEAT

Ch. 16.3

True False Statement True False

Heat engines can be internal or external, but neither are very

efficient

Hot water, steam and electric, and forced air heating all use conduction

and radiation to heat

Heat pumps reverse the normal flow of thermal energy, which is hot to

cold

Refrigerators and air conditioners are cooling systems, that don’t require

heat pumps

Refrigerants vaporize and condense over and over again

Heat Engines

Engine that burns fuel outside the engine Steam engine

Engine that burns fuel inside the engine Cars

External Combustion Engine

Internal Combustion Engine

Heating Systems

Central Heating Systems Heats many rooms from 1 central location Most use convection to distribute thermal

energy

Heating Systems

Conduction and radiation using water

Conduction and radiation using steam

Hot Water Heating Steam Heating

Heating Systems

Conduction and radiation using electrical energy

Convection using fans

Electric Baseboard Heating

Forced Air Heating

Cooling Systems

Heat pumps Device that reverses the normal flow of

thermal energy Circulates refrigerant through tubing

Refrigerant- fluid that vaporizes and condenses inside the tubing of a heat pump

Cooling Systems

Transfers thermal energy from the inside to the outside

Cools inside, releases hot air

Refrigerators Air Conditioners