Lecture 04

Question 1

What are the two laws of Ideal Gases?

Answer 1

1. At constant temperature, pV = constant (Boyle’s Law).
2. Adiabatic throttling causes no temperature change (JouleKelvin experiment)

Question 2

What is the “Ideal Gas Law”

Answer 2

The Ideal Gas Law: pV = nRT

p is Pressure, V is Volume, n is the number of moles of gas present, R is the universal gas constant, and T is absolute temperature.

Question 3

What is the Ideal Gas convention?

Answer 3

pV/T = mR or pv/T/R

where m is the mass of the gas, and R is a gas constant,
dependent on the type of gas considered (see Databook).

R relates to the universal gas constant (R₀) according to:

R = R₀ / M where M is the molecular weight of the gas.

Question 3

What are the 3 rules of Ideal Gases?

Answer 3

1. No intermolecular forces - Ideal gas molecules do not experience
   repulsive or attractive forces.
2. Ideal gas molecules take up no volume - If molecules occupied space, then the more we added, the less space they have to expand into, so the volume would decrease.
3. Gas particle collisions are perfectly elastic - No kinetic energy is lost when gas particles collide.

Question 4

What is the ratio of heat capacities?

Answer 4

The ratio of heat capacities at constant pressure (Cₚ) and
constant volume (Cᵥ) is useful in predicting the properties
of a fluid. This is given by the symbol 𝛾 where:

𝛾 = Cₚ/Cᵥ=

Question 5

Define enthalpy.

Answer 5

Enthalpy is defined as:

H = U + pV where H is enthalpy, U is internal energy, p is pressure and V is volume.

Question 6

Define entropy.

Answer 6

Entropy is defined as the amount of disorder in a