Chemical Reactions (and Stoichiometry)

Chemical reaction

A process in which one set of substances, called reactants, is converted to a new set of substances, called products.

Chemical change

A chemical reaction is the process by which a _____ occurs.

Types of physical evidence

• Color change

• Formation of a solid (precipitate) within a clear solution

• Evolution of a gas

• Evolution or absorption of heat

Stoichiometry

Area of study that examines the quantities of substances consumed and produced in chemical reactions.

Chemical equations

Are how chemists represent chemical reactions on paper.

(g)

Gas

(l)

Liquid

(s)

Solid

(aq)

Dissolve in aqueous (water) solution

Types of Chemical Reactions

1. Combination/Synthesis Reaction

2. Analysis/Decomposition Reaction

3. Single Displacement Reaction

4. Double Displacement Reaction

5. Combustion Reaction

Synthesis Reactions

• The direct union or combination of two substances to form a single compound.

• General formula: A + B → AB

Decomposition Reactions

• A single substance broken into two or more different substances

• General formula: AB → A + B

Single Displacement Reactions

• In this type of chemical reaction, an element and compound react and form a different element and a different compound.

• Cation exchange: A + BC → B + AC

• Anion exchange: A + BC → C + BA

Activity Series

• If an element is more reactive than its counterpart, then it is more likely to “steal” another cation/anion

• Can either be cation exchange or anion exchange

Double Displacement

• This happens when the positive and negative ions in the two compounds switch places forming two new compounds

• General formula: AB + CD → AD + CB

Combustion Reactions

• A chemical reaction in which a substance combines with oxygen and releases energy.

• Always produce carbon dioxide and water

• General formula: CxHy + O2 → CO2 + H2O or CxHyOz + O2 → CO2 + H2O

Formula Weight

The sum of the atomic weights (AW) of the atoms in the chemical formula of the substance.

Mole (mol)

In chemistry, the counting unit for numbers of atoms, ions, or molecules in a laboratory-size sample

Avogadro’s number

6.02 x 10^23

Molar Mass

The mass of 1 mol of the substance (g/mol)