# The Mole and Equations

## Basic Concepts

• Mole: A unit defined as the amount of a substance that contains as many entities (atoms, molecules, ions, etc.) as there are in 12 grams of carbon-12.
• Avogadro’s Number: The number of entities in one mole, approximately 6.022 x 10^23.
• Molar Mass: The mass of one mole of a substance, typically expressed in g/mol.

## Stoichiometry and Balancing Equations

• Equations must be balanced to reflect the Law of Conservation of Mass.
• Stoichiometry refers to the relationship between the amounts of reactants and products in a chemical reaction.
• Mole Ratios: The ratio of moles of one substance to the moles of another substance in a balanced chemical equation.

## Types of Reactions

• Combination Reactions: Two or more substances combine to form a new compound.
• Decomposition Reactions: A compound breaks down into two or more simpler substances.
• Oxidation-Reduction (Redox) Reactions: A transfer of electrons between substances. The substance losing electrons is oxidised, and the substance gaining electrons is reduced.
• Acid-Base Reactions: An acid donates a proton (H+) and a base accepts.

## Calculations Using the Mole

• Molar Volume: The volume occupied by one mole of any gas at standard temperature and pressure (STP), approximately 22.4 liters.
• Empirical Formula: The simplest whole-number ratio of atoms in a compound.
• Molecular Formula: The actual number of atoms in a molecule. -Determining empirical and molecular formulas requires mass spectrometry data and involves the concept of the mole.

## Equilibrium and Le Chatelier’s Principle

• Chemical Equilibrium: The state in which both reactants and products are present in concentrations which have no further tendency to change with time.
• Le Chatelier’s Principle: When a system at equilibrium is subjected to change, it will adjust in a way to counteract that change.
• Applications include adjusting conditions to favour the production of a desired product in industry.