Glossary
Absolute Zero
The theoretical temperature (0 Kelvin or -273.15°C) at which an ideal gas would have zero pressure and its particles would have minimal kinetic energy.
Example:
Scientists use liquid helium to cool materials to temperatures very close to Absolute Zero to study quantum phenomena.
Boltzmann constant (k_B)
A proportionality constant relating the average kinetic energy of particles in a gas to the gas's absolute temperature, used in the PV=NkT form of the ideal gas law.
Example:
To find the kinetic energy of a single gas molecule at a certain temperature, you would use the Boltzmann constant.
Boyle's Law
States that for a fixed amount of gas at constant temperature, pressure and volume are inversely proportional.
Example:
Squeezing a syringe with the end blocked demonstrates Boyle's Law as the volume decreases and the pressure of the trapped air increases.
Charles' Law
States that for a fixed amount of gas at constant pressure, volume and absolute temperature are directly proportional.
Example:
A hot air balloon rising as the air inside is heated is a classic demonstration of Charles' Law.
Combined Gas Law
A law that combines Boyle's, Charles', and Gay-Lussac's laws, relating the initial and final states of pressure, volume, and temperature for a fixed amount of gas.
Example:
If a weather balloon ascends, experiencing changes in both temperature and pressure, the Combined Gas Law can predict its new volume.
Elastic Collisions (Ideal Gas Assumption)
An assumption of the ideal gas model stating that collisions between gas particles and with container walls conserve total kinetic energy.
Example:
When billiard balls bounce off each other without losing energy, they demonstrate elastic collisions, similar to ideal gas particles.
Ideal Gas
A theoretical gas model based on assumptions that simplify gas behavior, useful for approximating real gas properties under many conditions.
Example:
While no gas is perfectly Ideal Gas, helium at room temperature and atmospheric pressure behaves very closely to one.
Ideal Gas Law
A fundamental equation describing the behavior of an ideal gas, relating its pressure, volume, temperature, and the number of particles.
Example:
The Ideal Gas Law helps engineers predict how much air to pump into a car tire to reach a specific pressure at a given temperature.
Ideal gas constant (R)
A proportionality constant used in the ideal gas law (PV=nRT) that relates energy to temperature and amount of substance.
Example:
When calculating the pressure of a gas given its moles, volume, and temperature, you'll use the ideal gas constant R.
No Intermolecular Forces (Ideal Gas Assumption)
An assumption of the ideal gas model stating that gas particles do not exert attractive or repulsive forces on each other, except during collisions.
Example:
The reason an ideal gas doesn't condense into a liquid at typical temperatures is because there are no intermolecular forces between its particles.
Number of atoms (N)
The total count of individual atoms or molecules present in a gas sample.
Example:
The number of atoms in a small helium balloon is enormous, even though helium is a light gas.
Number of moles (n)
A unit of measurement for the amount of substance, representing Avogadro's number of particles (6.022 x 10^23).
Example:
A chemist might measure out 0.5 number of moles of a gas for an experiment.
Pressure (P)
The force exerted per unit area by gas particles colliding with the walls of their container.
Example:
When you inflate a balloon, the increasing pressure inside pushes the rubber outwards.
Random Motion (Ideal Gas Assumption)
An assumption of the ideal gas model stating that gas particles move continuously and unpredictably in all directions.
Example:
The way perfume scent quickly spreads across a room is due to the random motion of its vapor molecules.
Real Gases
Gases that deviate from ideal gas behavior, especially at high pressures and low temperatures, due to the significant volume of particles and presence of intermolecular forces.
Example:
Water vapor at high pressure and low temperature behaves more like a Real Gas than an ideal gas, as its molecules start to attract each other.
Temperature (T)
A measure of the average kinetic energy of the gas particles, always expressed in Kelvin for gas law calculations.
Example:
Heating a pot of water increases the temperature of the air above it, causing the air molecules to move faster.
Tiny Particles (Ideal Gas Assumption)
An assumption of the ideal gas model stating that the volume occupied by the gas particles themselves is negligible compared to the total volume of the container.
Example:
In a large balloon, the individual air molecules are considered tiny particles relative to the balloon's overall volume.
Volume (V)
The three-dimensional space occupied by a gas.
Example:
A scuba tank holds a large volume of compressed air.