Gaseous state

Question 1

Avogadro’s Law

Answer 1

Equal volumes of all gases, under the same temperature and pressure, contain the same number of particles

Question 2

Mole

Answer 2

One mole contains exactly 6.02 x 10^23 elementary entities

Question 3

Assumptions about Idea gases

Answer 3

1. Gas particles have negligible volume compared to the volume of the container
2. The intermolecular forces of attraction between gas particles are negligible
3. Collisions between gas particles, and their collisions with the walls of the container, are perfectly elastic.

Question 4

Conditions for real gases to behave ideally

Answer 4

1. Low pressures
   At low pressures, the gaseous molecules are relatively far apart. The volume of the molecules themselves is negligible compared to the volume of the container. Thus, real gas molecules at low pressure can be approximated to have negligible volume. Also, intermolecular forces are negligible as the particles are far apart. Hence, their behaviour at low pressures would approach that of ideal gases
2. High temperatures
   At high temperatures, gas particles have enough kinetic energy to overcome intermolecular forces which can thus be considered insignificant. As such, the behaviour of real gases approach ideal gas behaviour at high temperatures.

Question 5

Explain deviations of gas at high pressure

Answer 5

At high pressure, the volume of the container decreases, The molecules are pushed closely together and take up a significant portion of the container volume, resulting in less space in which the molecules can move. Thus it is no longer valid to assume that its volume is negligible compared to the container volume, and so the gas deviates from ideal behaviour.

Question 6

Explain deviations at low temperatures

Answer 6

As temperature is lowered, the kinetic energy of the gas particles decreases, causing them to move more slowly and intermolecular forces to become more significant. This also causes collisions to become inelastic. Eventually, it reaches a point where the particles can no longer overcome the intermolecular forces, at which point real gases liquefy.