(d) ideal gas molecules

how molecules in a gas have random motion (5.15)

the gas particles move very quickly in random directions, meaning that they frequently collide with other particles and the wall of the container they are in. the effect of the collisions with the container is the production of a net force acting at right angles to the container walls, which is detected as gas pressure

the pressure caused by a gas can be calculated using the equation pressure = force / area

absolute zero (5.16)

at absolute zero, particles have no thermal or kinetic energy, so they are completely unable of exerting any sort of force. absolute zero is 0 kelvin, or -273°C

what is kelvin (5.17 / 5.19)

1 degree kelvin is equivalent to 1 degree celsius, but each temperature in kelvin is 273 degrees more than the same temperature in celsius

e.g. 0 kelvin = -273 celsius, 100 celsius = 373 kelvin etc.

the kelvin temperature of a gas is proportional to the average kinetic energy of its molecules

an increase in temperature results in? (5.18)

an increase in average speed of gas molecules, because the higher the temperature of a gas, the higher the levels of kinetic energy of the gas particles, increasing the average speed

qualitative relationship between pressure and volume at constant temperature for a fixed amount of gas (5.20)

as a gas heats, the kinetic energy of the gas particles increases, and so does their average speed. this means that there are more collisions per second with the walls and they exert a larger force on the wall. this causes the total pressure being exerted by the particles to rise.

if the temperature of the gas is constant, the average speed of the particles is constant.

qualitative relationship between pressure and Kelvin temperature at constant volume for a fixed amount of gas (5.20)

if the same number of particles is placed in a container of smaller volume they will hit the walls of the container more often. more collisions per second means that the particles are exerting a larger force on the wall over the same time, so average force exerted on the walls has increased

relationship between the pressure and kelvin temperature of a fixed mass of gas at constant volume (5.21)

p₁ / T₁ = p₂ / T₂

relationship between the pressure and volume of a fixed mass of gas at constant temperature

p₁V₁ = p₂V₂