Chapter 9 Equations Nature of Chemical Reactions Process

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 • Na. Cl Na + Cl 2 – Single Replacement • Element + Compound • Pb + HCl Pb. Cl 2 + H 2 – Double Replacement • 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.