Chapter 11 - Thermal Properties of Matter

Question 1

Define Heat Capacity

Answer 1

The amount of thermal requires to raise the temperature of a substance by 1 kelvin/ 1 degree celsius

Question 2

Heat capacity depends on Mass and ______ ?

Answer 2

Type of material

Question 3

Formula for heat capacity

Answer 3

Heat energy = Heat Capacity x Temperature Change

Question 4

S.I Unit for heat capacity

Answer 4

J/ Degree Celsius or Kelvin

Question 5

S.I Unit for Heat ENERGY

Answer 5

Joules (J)

Question 6

Why can changes in temperature can be given in either Kelvin or Degree Celsius?

Answer 6

When we talk about the change in temperature, the unit is not important, rather, the Value is the most important

Question 7

Heat energy absorbed by a body
=
_____ in the ______ energy of the molecules
=
_____ _____ due to movement of the molecules
+
_____ _____ due to the intermolecular forces

Answer 7

Increase in the internal energy
Kinetic Energy
Potential Energy

Question 8

A rise in temperature will take place if ?

Answer 8

ONLY the average kinetic energy of the molecule increase

Question 9

A CHANGE of state will occur if ?

Answer 9

ONLY the potential energy of the molecules changes

Question 10

Potential energy of the molecules is depend on which 2 condition?

Answer 10

Intermolecular forces

Space between intermolecular forces

Question 11

Define SPECIFIC heat capacity

Answer 11

The amount of thermal energy requires to raise the temperature of a unit mass of a substance by 1 Kelvin / 1 Degree Celsius

Question 12

S.I. Unit of Specific heat capacity

Answer 12

J/kg Kelvin or Degree Celsius

Question 13

Formula for specific heat capacity

Answer 13

Heat capacity = MASS x Specific heat capacity

Question 14

If Iron has a specific heat capacity of 460J/ kg Kelvin, what does it mean?

Answer 14

It means that 460 J of HEAT energy is required to raise the temperature of 1 kg of iron by 1 Kelvin

Question 15

Formula linking Heat ENERGY and SPECIFIC heat capacity

Answer 15

Heat energy = Mass x Specific Heat Capacity x Temperature Change

Question 16

What is the law of conservation of energy

Answer 16

Thermal energy lost = Thermal energy gained

Question 17

Formula of ENERGY

Answer 17

Energy = Power x Time

Question 18

Formula linking Power and Specific Heat capacity

Usually use in Qn that consist of a heater and a substance to find out the Specific Heat Capacity

Answer 18

Power x Time = Mass x Specific Heat Capacity x Temperature Change

Question 19

Explain how a sea breeze occur?

Answer 19

Due the land have a much smaller heat capacity than the water in the sea, the land heat up faster, causing a difference in temperature between the land and the sea. Due to convection, which hot air will rise up and cold air will rush in to replace the hot air, the sea breeze then occur as the movement of cold air. (Wind = movement of air)

Question 20

During the change of state, what happen to the temperature?

Answer 20

Remain constant

Question 21

Melting and Freezing only occur at a DEFINITE temperature provided that ?

Answer 21

The substance is pure

Question 22

Why during the change of state, the temperature of the substance is unchanged/

Answer 22

ALL thermal energy absorbed is used to BREAK the strong BONDS between particles.
The particles can MOVE OUT of their FIXED position
Hence they are further apart from one another
Thus the change of state occurs
Only the total INTERNAL POTENTIAL Energy is increased, not the kinetic energy

Question 23

Define latent heat of fusion

Answer 23

The amount of thermal energy required to change a substance from solid state to liquid state, WITHOUT a change in temperature

Question 24

S.I Unit for Latent heat of fusion/vaporisation

Answer 24

Joules (J)

Question 25

Define specific latent heat of fusion

Answer 25

The amount of thermal energy required to change a unit mass of substance from solid state to liquid state, WITHOUT a change in temperature

Question 26

S.I Unit for Specific Latent heat of fusion/vaporisation

Answer 26

J/Kg

Question 27

Formula linking Latent heat of FUSION and Specific latent heat of FUSION

Answer 27

Lf = Mass x &f

Question 28

Define latent heat of vaporisation

Answer 28

The amount of thermal energy required to change substance from LIQUID state to GASEOUS state, WITHOUT a change in temperature

Question 29

Define SPECIFIC latent heat of vaporisation

Answer 29

The amount of thermal energy required to change a unit mass of a substance from LIQUID state to GASEOUS state, WITHOUT a change in temperature

Question 30

Formula linking Latent heat of vaporisation and specific latent heat of vaporisation

Answer 30

Lv = Mass x &v

Question 31

During boiling, why the temperature of water remains constant even when thermal energy is continuously absorbed by the water molecules?

Answer 31

ALL the LATENT HEAT absorbed is used to break the strong intermolecular bonds between the water molecules. Also to overcome the atmospheric pressure in order to escape into the air. The molecules are then able to move further apart from each other. During the process, latent heat is only used to increase the total internal potential energy. When these happens, a change of state takes place, water become steam.

Question 32

How are pressure and impurities affects the boiling and melting points?

Answer 32

Impurities lowers the melting points
Impurities raise the boiling points

Pressure lowers the melting points
Pressure lowers the boiling points

Question 33

For condensation and freezing, what is lost from the substance?

Answer 33

Latent heat is lost

Question 34

What are the 6 differences between boiling and evaporation?

Answer 34

Boiling occurs at a fixed temperature
Evaporation occur at any temperature

Boiling take place throughout the liquid
Evaporation take place only on the surface of water

Boiling is a fast process
Evaporation is a slow process

Boiling requires an external thermal energy source
Evaporation does not require an external thermal energy source

Temperature remain constant during boiling
Temperature may change during evaporation

Bubbles are formed during boiling
No bubbles formed during evaporation

Question 35

What are the 2 similarities of boiling and evaporation?

Answer 35

It involves a CHANGE OF STATES from liquid to gas

Both requires LATENT HEAT

Question 36

4 factors affects rate of evaporation, Rate of evaporation increase if:

Answer 36

Temperature increases
Surface area increases
Humidity decreases
Speed of the movement of surrounding air increases
(wind)

Question 37

How evaporation caused cooling in the ETHER Experiment? What are the observation and explanation for the experiment?

Answer 37

After the experiment conducted for some time, the break sticks to the wooden block.
The water between the wooden block and the breaker freeze and form a thin layer of ice

As the ether evaporates, cooling takes place and cause the temperature of the ether to decrease.
When the temperature of ether is decreased to a value that is lower than the water, the heat energy is then flow from the pool of water to the ether. Eventually, the temperature of the water will fall to 0 degree celsius and thus freezing occurs.

Question 38

Using the kinetic theory, explain why evaporation cause cooling

Answer 38

According to the kinetic theory, the molecules in liquid moves in a continuous random motion. The molecules are moving at a DIFFERENT SPEED. The AVERAGE Kinetic energy of the molecule is proportional to the temperature of the liquid.
The fast moving molecules, especially the ones who are nearer to the surface of the liquid, will overcome the intermolecular force between itself and the neighboring molecule and escape into the air.
The liquid thus left with slower moving molecules and this causes the average kinetic energy of the molecule to decrease, results in a decrease in temperature of the liquid, and thus cooling takes place.