Topic 3.1: Thermal Concepts

Question 1

Define temperature

Answer 1

o TEMPERATURE: A measurement of how hot an object is. A scalar quantity. If two objects have the same temperature, there will be no net heat flow between them.

Question 2

What does temperature determine in terms of thermal energy transfer?

Answer 2

• 3.1.1: State that temperature determines the direction of thermal energy transfer between two objects

Question 3

• 3.1.2: State the relation between the Kelvin and Celsius scales of temperature

Answer 3

o Temperature in Kelvin = Temperature in Celsius + 273

Question 4

Define absolute zero

Answer 4

o ABSOLUTE ZERO: The lowest temperature possible. -273.16°C or zero kelvin (0K). Kelvin is the absolute thermodynamic temperature scale.

Question 5

Define internal energy

Answer 5

• 3.1.3: State that the internal energy of a substance is the total potential energy and random kinetic energy of the molecules of the substance

Question 6

Where does the kinetic energy arise from?

Answer 6

o The kinetic energy of the molecules arises from their random/translational/rotational motion

Question 7

Where does the potential energy arise from?

Answer 7

o The potential energy of the molecules arises from the forces between the molecules

Question 8

• 3.1.4: Explain and distinguish between the macroscopic concepts of temperature, internal energy and thermal energy (heat)

Answer 8

o Thermal energy refers to the non-mechanical transfer of energy between a system and its surroundings

Question 9

Define mole

Answer 9

o MOLE: The amount of a substance that contains the same number of particles as there are atoms in 12g of carbon-12.

Question 10

Define molar mass

Answer 10

o MOLAR MASS: The mass of 1 mole of a substance. eg molar mass of water is 18g

Question 11

Define Avogadro’s constant

Answer 11

o AVOGADRO CONSTANT: The number of particles in a mole. A= 6.02 x 10^23