Classifying Chemical Reactions

Synthesis Reaction Two or more reactants form a single product Example: A + B  AB 2 Fe + 3 Cl 2  2FeCl 3

Combustion Reaction Oxygen combines with a substance and releases energy in the form of heat and light (water is a product) Examples: 2 H 2 + O 2  2 H 2 O CH 4 + 2O 2  CO H 2 O All reactions where a hydrocarbon reacts with oxygen will always form carbon dioxide and water as products

Decomposition Reaction Single compound breaks down into two or more elements or compounds Example: AB  A + B NH 4 NO 3  N 2 O + 2 H 2 O

Single Replacement Reaction A reaction in which the atoms of one element replace the atoms of another element in a compound Example: A + BX  AX + B 2 Li + 2 H 2 O  2 LiOH + H 2

Metathesis (Double Replacement) Reaction Exchange of ions between two compounds Example: AX + BY  AY + BX Ca(OH) HCl  CaCl H 2 O

Predicting Products of Chemical Reactions Class of ReactionReactantsProducts SynthesisTwo or more substancesOne compound CombustionA metal and oxygen A nonmetal and oxygen A compound and oxygen The oxide of the metal The oxide of the nonmetal Two or more oxides (water is usually a product of all of these) DecompositionOne compoundTwo or more elements and/or compounds Single-ReplacementA metal and a compound A nonmetal and a compound A new compound and the replaced metal A new compound and the replaced nonmetal Double-Replacement (Metathesis) Two compoundsTwo different compounds, one of which is often a solid, water or a gas

Practice Problem How would you classify the following chemical reaction? 2 C 4 H O 2  8 CO H 2 O Answer: Combustion

Practice Problem How would you classify the following reaction? Al + I 2  AlI 3 Answer: Synthesis

Practice Problem How would you classify the following reaction AgNO 3 + Na 2 S  Ag 2 S + NaNO 3 Answer: Metathesis (Double Replacement)

Practice Problem Predict the products to the following reaction. 2 K + ZnCl 2  Answer: Single Replacement 2 KCl + Zn

Predict the products to the following chemical reaction. 2 NaN 3  Answer: Decomposition 3 N Na