Heat

Question 1

What is the kinetic molecular theory?

Answer 1

The theory that describes the motion of molecules or atoms in a substance in terms of kinetic energy. Kinetic energy causes particles to be in a state of constant motion.

Question 2

Define thermal energy?

Answer 2

The total quantity of kinetic and potential energy possessed by the atoms or molecules of a substance. The amount of thermal energy within an object determines how fast it’s particles move (vibrate) therefore how hot/cold it is.

Question 3

What does an object do when it absorbs thermal energy?

Answer 3

The object warms up.

Question 4

What does an object do when it releases thermal energy?

Answer 4

The object cools down.

Question 5

How can thermal energy be transferred?

Answer 5

Thermal energy can be transferred from warm object to cool but not from cool to warm.

Question 6

Define temperature

Answer 6

A measure of the average kinetic energy of particles in a substance. It is measured using a mercury or alcohol thermometer.

Question 7

What are the 3 different temperature scales?

Answer 7

Celsius, Fahrenheit, Kelvin

Question 8

What is the Celsius scale?

Answer 8

This scale is based on the boiling point and freezing point of water. It freezes at O and boils at 100.

Question 9

What is the Fahrenheit scale?

Answer 9

This scale is based on the boiling point and freezing point of brine. It freezes at 32 and boils at 212.

Question 10

What is a melting point?

Answer 10

It is the temperature at which a solid changes to a liquid; equal to freezing point for given substances.

Question 11

What is a freezing point?

Answer 11

It is the temperature at which a liquid changes to solid; equal to the melting point for a given substance.

Question 12

What is a boiling point?

Answer 12

It is the temperature at which a liquid changes into a gas; equal to the condensation point for the given substance.

Question 13

What is a condensation point?

Answer 13

It is the temperature in which a gas changes into a liquid; equal to the boiling point for the given substance.

Question 14

Define heat

Answer 14

Heat is the transfer of thermal energy from a substance of high temperature to a substance of low temperature.

Question 15

What are the 3 methods of transferring thermal energy?

Answer 15

Conduction, Convection and Radiation

Question 16

What is conduction?

Answer 16

Conduction occurs when warmer objects are in physical contact with colder objects. The fast moving particles collide with the slow moving particles. (eg. placing a cold spoon in a hot cup of coffee)

Question 17

What is convection?

Answer 17

Convection is the transfer of thermal energy through a fluid (liquid, gas). This occurs with colder, more dense fluid falls and pushes up warmer, less dense fluid.

Question 18

What is a convection current?

Answer 18

A convection current occurs when a fluid is continuously heated. (eg. water boiling in a pot)

Question 19

What is radiation?

Answer 19

Radiation is the movie of thermal energy as electro-magnetic waves. Radiation waves can travel through air, glass or empty space.

Question 20

Define conductor

Answer 20

A conductor is a material which allows thermal energy to pass through it quickly and easily. (eg. metals)

Question 21

Define insulator

Answer 21

An insulator is a material that is a poor conductor of thermal energy. (eg. wood)

Question 22

What is the best insulator?

Answer 22

The best insulator is a vacuum because there are no particles. (eg. thermos bottle)

Question 23

Define specific heat capacity

Answer 23

Specific heat capacity (c) is the amount of energy required to increase the temperature by 1kg of a substance by 1 degree Celsius.

Question 24

Define quantity of heat

Answer 24

The total amount of thermal energy transferred from a warmer substance to a colder substance is called the quantity of heat (Q).

Question 25

If a substance absorbs energy, what is delta T?

Answer 25

Delta T or the change in temperature is positive.

Question 26

If a substance releases energy, what is delta T?

Answer 26

Delta T or the change in temperature is negative.

Question 27

What is the principal of thermal energy exchange?

Answer 27

The principal of thermal energy exchange states that when a warmer substance comes into contact with a colder one, thermal energy is transferred from the warmer object to the colder one until all of the thermal energy is evenly distributed (same final temperature for both substances).

Question 28

Define latent heat

Answer 28

Latent Heat (Q) is the total thermal energy absorbed or released when a substance changes state.

Question 29

Define latent heat of fusion

Answer 29

Latent Heat of Fusion is the amount of energy that is required to change state from solid into liquid (melt/freeze).

Question 30

Define latent heat of vaporization

Answer 30

Latent Heat of Vaporization is the amount of energy that is required to change state from liquid into gas (condensing/boiling).