Temperature + Thermal properties of matter

Question 1

Fixed points

Answer 1

Temperatures that are easily producible and remain the same at given conditions.

Question 2

Thermal equilibrium

Answer 2

Thermal equilibrium occurs when both substances are of the same temperature, and there is no net flow of thermal energy.

Question 3

Explain transfer of heat using kinetic energy.

Answer 3

The temperature of a substance is related to the kinetic energy (KE) of the molecules. A higher temperature means a higher average KE of the molecules. When two substances of different temperature are placed beside each other in contact, molecules with higher KE will collide and transfer some of their KE to slower-moving molecules. In this way we can see that thermal energy flows from a hotter region (higher temperature) to a cooler region (lower temperature).

Question 4

Thermometric property

Answer 4

A physical property which varies continuously with temperature. (MIGHT NOT BE LINEARLY)

Question 5

Measurement of thermometric properties

Answer 5

Volume: liquid in glass (mercury thermometer)
Electromotive force: thermocouple
Electrical resistance: Platinum resistance thermometer
Pressure: Constant volume gas thermometer

Question 6

Advantages of a thermocouple thermometer

Answer 6

1. It can operate over a wide range of temperatures (from −200 °C to 1700 °C), unlike a laboratory thermometer which is restricted by its boiling or melting point.
2. It can measure extremely high temperatures.
3. It can measure temperature at a specific point for large objects.
4. It can respond quickly to measure rapidly changing temperatures.

Question 7

Internal Energy, U

Answer 7

Sum of the kinetic energy of gas particles by virtue of their movements and vibrations and sum of the potential energy of the gas particles due to the intermolecular attraction between them.

Question 8

Heat Capacity, C

Answer 8

The amount of thermal energy required to raise the temperature of the body by 1 K or 1 °C.

Question 9

Specific heat capacity, c

Answer 9

The amount of thermal energy required to raise the temperature of 1 kg (or: unit mass) of the material by 1 K or 1 °C.

Question 10

Melting

Answer 10

A process where thermal energy supplied changes the state of a substance from solid state to liquid state without a change in temperature.

Question 11

Latent heat of fusion, Lf

Answer 11

The amount of thermal energy required in changing a substance from a solid into a liquid state (or vice versa), without a change in temperature.
Lf=Q

Question 12

Specific latent heat of fusion, lf

Answer 12

The amount of thermal energy required in changing 1 kg (or: unit mass) of substance from a solid into a liquid state (or vice versa), without a change in temperature.
Q= mlf

Question 13

Boiling

Answer 13

A process whereby energy supplied changes the state of a substance from liquid state to gaseous state, without a change in temperature.

Question 14

Latent heat of vaporization, Lv

Answer 14

The amount of thermal energy involved in changing a substance from a liquid into a gaseous state (or vice versa), without a change in temperature.

Question 15

Specific latent heat of vaporization, lv

Answer 15

The amount of thermal energy involved in changing 1 kg (or: unit mass) of substance from a liquid into a gaseous state (or vice versa), without a change in temperature.