Basics of Chemical Reactions Chemical Reactions are essential to everyday life Reactants yield products Chemical equation is used to represent a chemical reaction

The Four Indications a Chemical Reaction is Occurring Transfer in energy (hot or cold) Production of gas Change in color Precipitate forming

Example Everyday Reactions Iron + oxygen Iron (III) oxide (rust) Hydrogen Peroxide water and oxygen Methane carbon dioxide and oxygen

Types of Chemical Reactions Combination Reaction (synthesis): R + S RS Two elements or two compounds are reactants yielding one product

Decomposition Reaction: RS R + S Single binary compound or compound with polyatomic separating (decomposing)

Single-Replacement Reaction: T + RS TS + R Element and a compound (Potassium in water to make Potassium Hydroxide and Hydrogen)

Double Replacement Reaction: R + S - + T + U - RU(precipitate) + T + S - Precipitate: solid, liquid or gas that settle out of a solution One of the products in a double replacement will be a precipitate

Example Problems What type of chemical reaction are the following: SO 2(g) + O 2(g) SO 3(g) Fe 2 O 3 (s) + H 2(g) Fe (s) + H 2 O (l)

Balancing Chemical Reactions Just like the equality in math, the chemical reactions must be equal on both sides (due to the law of conservation of mass) Al (s) + N 2(g) AlN(s) Balance these equations using coefficients next to the compound

Balance These Equations and determine what type of reaction it is P (s) + O 2(g) P 4 O 10(s) NaN 3(s) Na (s) + N 2(g) Br 2(aq) + NaI (aq) NaBr (aq) + I 2(aq) KI (aq) + PB(NO 3 ) 2(aq) PbI 2(s) + KNO 3 (aq)

Rule of Thumb when balancing equations Remember the 7 diatomic molecules (in the reactions, they are formed as a diatomic) – Seven polyatomics: O 2, I 2, Br 2, Cl 2, F 2, N 2, H 2 Polyatomic ions usually stay as polyatomic ions. (Example: carbonate stay as a carbonate)

Catalysts Substance that speeds up the reaction, however is not used up in the reaction Hydrogen peroxide yields oxygen and hydrogen with a catalyst of manganese (IV) oxide Lawn mower works with a spark plug as a catalyst (electricity)

Objective: To practice balancing equations and naming reactions Do Now: Determine the type of reaction and balance it ___ Al + ___ S 8 ___Al 2 S 3