Fundamental Chemistry Concepts & Laws

Mol

The unit of amount of substance in the SI. It is the amount of substance that contains as many basic entities as there are atoms in 12 g of the isotope carbon-12.

Avogadro's Number (NA)

One mole contains Avogadro's number of particles: NA = 6.022045 × 10²³.

Molar Mass (M)

Mass of one mole of atoms or molecules. The numerical value of molar mass in grams matches the value of the mass in amu of its formula.

Molar Volume

Volume of 1 mole of a substance at a certain temperature (the temperature must be stated), whether solid, liquid, or gas.

Following Avogadro's principle, 1 mole of gas occupies the same volume when measured under the same conditions of pressure (p) and temperature (T), irrespective of the gas. Under standard conditions (0 °C and 1 atm), all gases considered ideal in behavior have the same volume: 22.4 L.

Dispersions

Systems formed by the interposition of small particles of two or more substances within another substance.

According to the dispersed particle size, dispersions are defined as:

Suspensions

• Particle diameter: 10^-4 - 10^-7 m.
• Properties: Cloudy, sediment, do not crystallize, and are separated by ordinary filtration.

Colloids

• Particle diameter: 10^-7 - 10^-9 m.
• Properties: Appearance is clear, no sediment, do not crystallize, and are separated by membrane filtration.

Solutions

• Particle diameter: 10^-9 - 10^-11 m.
• Properties: Looking clear and transparent, are crystallizable, do not settle, and are not separated by filtration.

Solubility

Concentration in the state of saturation; i.e., maximum concentration possible at a given temperature. Solubility depends on the chemical nature of the solute and solvent, temperature, pressure, and the presence of other substances.

Ideal Gas Laws

General Ideal Gas Equation

p₁v₁/t₁ = p₂v₂/t₂

Ideal Gas Law (Equation of State)

p · V = n R · T

Kinetic Theory of Gases

Gas molecules occupy no volume, move randomly with velocities whose mean depends on temperature, and collide elastically between themselves and the vessel walls, causing pressure.

Boyle's Law

p₁ · V₁ = p₂ · V₂

At constant temperature, the volume occupied by a gas is inversely proportional to the pressure it is under.

Charles's and Gay-Lussac's Laws

At constant pressure, the volume occupied by a gas is directly proportional to the absolute temperature.

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

Dalton's Law of Partial Pressures

The total pressure of a gas mixture equals the sum of the partial pressures of the constituent gases.

Amagat's Law of Partial Volumes

The total volume of a gas mixture equals the sum of the partial volumes of the constituent gases.