Heating Processes

Question 1

Kinetic particle model of matter

Answer 1

1. Particles are in constant, random motion
2. There are large gaps between molecules, and this is proportional to the potential energy of the particles
3. Collisions between particles are perfectly elastic.

Question 2

Thermal Energy

Answer 2

The internal energy of a system

Question 3

Heat

Answer 3

The process of transferring energy between systems.

Question 4

Temperature

Answer 4

The average kinetic energy of all the particles of a system

Change in Temperature= Change in Energy

Question 5

Internal energy

Answer 5

The total microscopic energy of the particles of a system

Question 6

Kinetic energy

Answer 6

The energy due to motion

Question 7

Conduction

Answer 7

Heat transfer through physical contact. Kinetic energy is transferred through particle vibrations between two substances of different energy

Question 8

Convection

Answer 8

Heat transfer through the physical movement of particles. it is large scale matter movement through a medium.

Question 9

Radiation

Answer 9

The transfer of heat through a vacuum via electromagnetic radiation.

Question 10

Specific heat capacity

Answer 10

The thermal energy required to raise the temperature of one kilogram of a substance by One-degree Celcius.

Question 11

The concept of proportionality

Answer 11

The specific heat capacity of a substance is specific to the substance and is related to objects chemical and physical properties, such as the size and strength of the intermolecular forces of that substance.

Question 12

Why does temperature remain constant in a phase change?

Answer 12

This is because it requires a large amount of energy to increase the potential energy of the particles. Instead of increasing the temperature, (or the average Kinetic energy), The energy goes into breaking the bonds between the atoms. Potential energy increases until all the bonds have been broken; only then can the kinetic energy and temperature of the particles increase. Internal energy remains constant during a phase change.

Question 13

Specific latent heat

Answer 13

The amount of thermal energy required to complete a phase change of a substance, either through vaporisation or fusion.

Question 14

Thermal equilibrium

Answer 14

A state where two substances in contact exchange no energy between them. Therefore, their kinetic energy is the same, and so is their temperature

Question 15

Zeroth Law of thermodynamics

Answer 15

Energy is exchanged until thermal equilibrium is reached. If a body is in thermal equilibrium with two other bodies that are in thermal equilibrium with each other, then they are all in thermal equilibrium.

Question 16

Is Heat equivalent to Work?

Answer 16

Essentially. A system with thermal energy can do work. Because thermal energy is a measure of internal energy, if energy is added, the temperature increases and so does the kinetic energy of the particles. It is this kinetic energy that can do work. Mechanical energy can be converted into thermal energy.

Question 17

Change of internal energy

Answer 17

The change in internal energy is equivalent to the energy added or removed and the work done on or by the system. This is a consequence of the First Law of thermodynamics.

Change in energy = Work + Thermal energy
Change in U = W + Q

Additionally, this can be explained by the conservation of energy, which states that energy cannot be created nor destroyed, only transferred and transformed.

Question 18

What are some disadvantages of energy transfers?

Answer 18

Energy transfers and transformations usually result in heat loss to the environment, consequently decreasing the amount of useable energy available.

Work = Loss of thermal energy
W = -Q

Question 19

Thermal efficiency

Answer 19

The ability of a machine to convert heat into useful energy, quantified by the ratio of energy output over energy input. The higher the percentage the greater the efficiency, and vice-versa.