3. gaseous state

Force exerted per unit area
SI units: Pascals (Pa), Nm^-2

atm: 101 325 Pa
bar: 100 000 Pa

The volume occupied by a gas at a specified temperature and pressure

At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure.

Graphs:
1. P against V: y = 1/x
2. P against 1/V: y = mx

At constant pressure, the volume if a fixed mass of gas is directly proportional to its absolute temperature in K

V against T/K: y = mx
V against T/°C: y = mx + c, x intercept being -273 (due to K to °C conversion)

At constant temperature and pressure, the volume of a gas is directly proportional to the number of moles of a gas present

V against n: y = mx

PV=nRT

R = 8.31 J K^-1 mol^-1

A gas that follows the ideal gas equation PV = nRT exactly, under all conditions of pressure,volume and temperature.

PV = (m/Mr)RT

(P1V1)/T1 = (P2V2)/T2

useful for gas systems where the total moles of gas remains constant

1. Draw a vertical line
2. At the value of x, compare y values and find eason for the difference

If a mixture of a gas is confined in a container, each gas occupies the same volume of the container and exerts its own pressure on the walls of the container as if it were the only gas present.

P(gas) = (n(gas)/n(total)) x P(total)
Hence, partial pressure of any individual gas is directly proportional to its mole fraction in the mixture

Negligible volume
Negligible IMF between gas particles
Collisions are perfectly elastic; no KE lost

1. Low pressures: gas particles will be far apart, for negligible volume and IMF
2. High temperatures: for high KE that will overcome IMF

1. Pressure of molecules

2. Strength of dispersion forces; stronger = more deviation
E.g., CO2 vs NH3. As CO2 has a larger electron cloud, there are stronger dispersion forces between CO2 molecules than NH3 molecules, and have greater deviation

3. For molecules with similar dispersion forces, compare other intermolecular forces

High pressure = volume of container decreases and molecules are pushed closely together, taking up a significant portion of container volume. Not negligible, hence deviate.

Close together = non-negligible IMF

Low temperatures = KE decreases and particles move more slowly, hence IMF increases. no longer negligible. Collisions also inelastic.

Eventually, particles can no longer overcome IMF and will liquefy below its boiling point.

intermolecular forces of attraction is the main factor in effect.
As pressure increases, gas molecules are closer to each other, resulting in stronger intermolecular forces, and decreasing the observed P, hence decreasing PV

non-negligible volume compared to the volume of the container, hence increasing the observed V value and increasing PV, causing deviation from ideal gas.

Heavier molecules travel slower and vice versa.

Note that replacing molecular speed with kinetic energy would result in the same shape

Alternatives to fraction of molecules: number of gas particles, proportion of particles

Peak of the curve represents the most probable speed

All curves start at (0,0) for no of particles against temp graphs

Asymptote at the end ! no maximum speed because there is no theoretical limit