Moles & Stoichiometry

A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion
Types of chemical formulas include empirical, molecular, and structural
The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound
It many be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound
In all chemical reactions there is a conservation of mass, energy, and charge
The molar mass (gram formula mass) of a substance equals one mole of that substance
The percent composition by mass of each element in a compound can be calculated using these gram formula masses

Moles
1 mole = gram formula mass
1 mole = 6.02x10^23 particles
1 mole = 22.4L of any gas at STP

Types of Equations

Combustion: A combustion reaction is when oxygen combines with another compound to form water and carbon dioxide. These reactions are exothermic. 
C₁₀H₈ + 12 O₂ ---> 10 CO₂ + 4 H₂O

Synthesis: When two or more simple compounds combine to form a more complicated one. These reactions come in the general form of: A + B ---> AB

Decomposition: A complex molecule breaks down to make simpler ones. AB ---> A + B

Single replacement: When one element trades places with another element in a compound. 
A + BC ---> AC + B

Double replacement: When the anions and cations of two different molecules switch places, forming two entirely different compounds. AB + CD ---> AD + CB
Identify the precipitate using Table F

Moles Regents Questions