Chapter 9 Equations

Nature of Chemical Reactions Process in which one or more substances are converted into new substances. Reactants  Products Reactants- Products-

Chemical Equations Word Equations vs. Formula Equations – Symbols + on the left means “reacts with” + on the right means “and”  means to “ to form, or decompose into” The words for the formulas or elements are the same Examples

Balancing Equations The number of atoms on the left must equal the number of atoms on the right. The only numbers that can be added to the equations are coefficients 5 rules or guidelines – Balance metals 1 st – Balance polyatomics 2 nd – Balance nonmetals except hydrogen and oxygen 3 rd – Balance hydrogen and oxygen 4 th – Fix and problems or mistakes last Examples

Writing Complete Chemical Equations Complete means to add in the phases aq = solution with water s = solid l = liquid g = gas Water is always a liquid Metals by themselves are usually solid

Classification of Reactions Five different classifications – Synthesis One compound or molecule being produced Fe + O 2  Fe 2 O 3 – Decomposition One compound or molecule on the reactants side NaCl  Na + Cl 2 – Single Replacement Element + Compound  Element + Compound Pb + HCl  PbCl 2 + H 2 – Double Replacement Compound + Compound  Compound + Compound K 2 O + H 2 SO 4  K 2 SO 4 + H 2 O – Combustion Having Oxygen on the Reactant side C 2 H 2 + O 2  CO 2 + H 2 O

Predicting Products You classify the reaction.