S1.5: Ideal Gases

Question 1

Define the term ideal gas: (2)

Answer 1

• A hypothetical gas (1)
• That obeys the gas laws and the kinetic-molecular theory. (1)

Question 1

Describe the rules of the kinetic molecular theory: (5)

Answer 1

• Particles of an ideal gas are in constant, random straight line motion. (1)
• Collisions between particles of an ideal gas are elastic meaning that total kinetic energy is conserved. (1)
• The volume occupied by the particles of an ideal gas is negligible relative to the volume of the container. (1)
• There are no intermolecular forces acting between particles of an ideal gas. (1)
• The average kinetic energy of the particles of an ideal gas is directly proportional to the absolute temperature in kelvin. (1)

Question 2

Describe how real gases deviate from ideal gas behaviour (4)

Answer 2

• Real gases have a finite, measurable volume (1)
• Real gases have intermolecular forces that act between the particles. (1)
• Real gases showcase ideal behaviour at relatively high temperatures and low pressures. (1)
• They deviate the most from ideal behaviour at low temperatures and high pressures. (1)

Question 3

State what PV/RT is equal to when there is one mole of an ideal gas. (1)

Answer 3

1 (1)

Question 4

State the value of PV/RT when there is low pressure of a real gas: (1)

Answer 4

• Less than 1 (1)