UNIT 6

Pressure

The force exerted by the gas particles per unit area on the walls of its container.

Dalton’s law of partial pressures

The total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of each individual gas.

Boyle’s Law

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

Charles’ Law

At constant pressure, the volume of a gas is directly proportional to its absolute temperature.

Gay-Lussac’s Law

At constant volume, the pressure of a gas is directly proportional to its absolute temperature.

Combined Gas Law

A relation between pressure, volume, and temperature for a fixed amount of gas.

Avogadro’s Law

Equal volumes of gases at the same temperature and pressure contain an equal number of molecules.

Ideal Gas Law

The equation that relates pressure, volume, temperature, and number of moles of an ideal gas: $PV = nRT$.

Ideal gas constant

The constant R in the ideal gas law, with a value of $0.0821 ext{ L atm} ext{K}^{-1} ext{mol}^{-1}$.

Soluble

The property of a substance to dissolve in a solvent.

Solution

A homogeneous mixture of two or more substances.

Suspension

A mixture in which particles are dispersed throughout a liquid or gas but are not dissolved.

Colloid

A mixture where tiny particles of one substance are evenly distributed within another without settling.

Electrolyte

A substance that dissociates into ions when dissolved in water, conducting electricity.

Non-electrolyte

A substance that does not dissociate into ions and does not conduct electricity in solution.

Absolute zero

Theoretically, the lowest temperature possible, at which molecular motion comes to a complete stop, measured as 0 Kelvin or -273.15 °C.

Saturated solution

A solution in which no more solute can dissolve at a given temperature.

Supersaturated solution

A solution that contains more dissolved solute than what is required to reach equilibrium at a given temperature.

Molarity

A concentration unit defined as the number of moles of solute per liter of solution (mol/L).

Ideal gas law calculations

Using the equation $PV = nRT$ to find pressure, volume, temperature, or moles.

Boyle's law calculation

Finding the final volume or pressure of a gas using the relation $P_1V_1 = P_2V_2$.

Charles' law calculation

Finding the volume or temperature of a gas using the relationship $V_1/T_1 = V_2/T_2$.

Relationship of kinetic molecular theory to gas laws

Gas laws derive from the kinetic theory, which describes gases as composed of tiny particles in constant, random motion.

Factors that increase solubility

Temperature, pressure, and nature of solute and solvent can increase solubility.

Kinetic molecular theory definition

A theory that explains the behavior of gases, stating that gas particles are in constant motion and the average kinetic energy is proportional to temperature.

Ideal gas assumptions

Gas particles have no volume, no intermolecular forces, and undergo elastic collisions.

Real gas vs. ideal gas

Real gases have interactions and occupy volume; ideal gases follow the gas laws perfectly without exceptions.

Solubility of gases and temperature/pressure

Gases are more soluble at higher pressure and lower temperatures.

Properties of solids, liquids, gases

Solids have fixed shape and volume, liquids have fixed volume but adapt to shape, and gases have neither fixed shape nor volume.

How a substance dissolves

Dissolving occurs when solute particles are surrounded by solvent molecules, breaking intermolecular forces and mixing.