Chemical Reactions

Chemical Reaction…

Not a Chemical Reaction…

What is a Chemical Reaction? A process in which new substances with new chemical and/or physical properties are formed. A burning piece of paper (Chemical Reaction): paper  ashes, water vapor, and carbon dioxide Dissolving salt in water (No Reaction): Salt + Water → Salt + Water

Parts of a Chemical Equation Na+ Cl → NaCl sodium and chlorine yields sodium chloride Reactants The substances that you start with. In this case: Sodium and Chlorine “Yields” This arrow tells you that the reactants become the products through a chemical reaction. Products The substances you end with. In this case: Sodium Chloride

Mg + O2 → MgO H2O → H2 + O2 C4H10 + O2→CO2 + H2O Chemical Equations magnesium and oxygen yields magnesium oxide H2O → H2 + O2 water yields hydrogen and oxygen C4H10 + O2→CO2 + H2O butane and oxygen yields carbon dioxide and water

Types of Chemical Reactions Type 1: Synthesis In a synthesis reaction, two (or more) simple substances form a more complex substance. Synthesis: Two Become One A + B → AB

Synthesis Example Na + Cl → NaCl sodium and chlorine yields sodium chloride

Types of Chemical Reactions Type 2: Decomposition In a decomposition reaction, a complex substance is broken down into two (or more) simpler substances. Decomposition: One Becomes Two AB → A + B

Decomposition Example H2O2 → H2O + O2 hydrogen peroxide yields water and oxygen

Types of Chemical Reactions Type 3: Single Replacement Reaction In a single replacement reaction, a single element replaces another element in a compound. Single Replacement: Start with one compound, end with a different compound.

A + BC B + AC Single Replacement Reaction

Single Replacement Example Zn + HCl → H2 + ZnCl2 zinc and hydrochloric acid yields hydrogen and zinc chloride

Types of Chemical Reactions Type 4: Double Replacement Reaction In a double replacement reaction, elements from two compounds switch places and form two new compounds. Double Replacement: Start with two compounds, end with two different compounds.

AB + CD CB + AD Double Replacement Reaction