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Classifying. Chemical Reactions. Classifying Chemical Reactions. Reactions are either classified by: how much energy is given off or absorbed how the atoms are rearranged. Chemical Reactions and Energy. Exothermic Reactions produce energy (heat, light, sound). e.g.
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Classifying Chemical Reactions
Classifying Chemical Reactions • Reactions are either classified by: • how much energy is given off or absorbed • how the atoms are rearranged Chemical Reactions and Energy • Exothermic Reactions • produce energy (heat, light, sound) e.g. CH4(g) + O2(g) H2O(g) + CO2(g) + energy • Endothermic Reactions • absorb energy (heat, light, sound) e.g. CaCO3(s) + energy CaO(s) + CO2(g)
Chemical Reactions and Atom Rearrangement • Synthesis Reactions (Combination) • 2 or more substances combine to form a compound General Formula: A + B AB 1 PRODUCT e.g. S(s) + O2(g) SO2(g) 2 elements 2SO2(g) + O2(g) 2SO3(g) 1 element, 1 compound SO3(g) + H2O(l) H2SO4(g) 2 compounds • Decomposition Reactions • 1 substance breaks down into 2 or more simpler substances General Formula: AB A + B 1 REACTANT e.g. 2H2O(l) 2H2(g) + O2(g)
Single Replacement Reactions (Displacement) • A combined element in a compound is replaced by an uncombined element. General Formula: Z + AB AZ + B Metals replace metals; Non-metals replace Non-metals e.g. Br2(l) + 2NaCl(aq) 2NaBr(aq) + Cl2(g) 2Al(s) + Fe2O3(s) 2Fe(l) + Al2O3(s) • Double Replacement Reactions (Ionic) • Elements in different compounds replace each other (exchange places) General Formula: AB + XY AY + XB e.g. 2KI(aq) + Pb(NO3)2(aq) PbI2(s) + 2KNO3(aq) 2KI(aq) +Pb(NO3)2(aq) PbI2(s) + 2KNO3(aq) One of the products often forms a precipitate.(an insoluble solid that separates from the solution)
Neutralization (Acid-Base) • A type of double replacement reaction that involves an acid reacting with a base to produce water and a salt. General Formula: Acid + Base Water + Salt e.g. HCl(aq) + NaOH(aq) HOH(l) + NaCl(aq) HCl(aq) + NaOH(aq) HOH(l) + NaCl(aq) • Combustion • A special type of exothermic reaction where oxygen is a reactant and oxides are produced with a large amount of energy. e.g. CH4(g) + 2O2(g) CO2(g) + 2H2O(l) + energy 2H2(g) +O2(g) 2H2O(l) + energy 2Mg(s) +O2(g) 2MgO(s) + energy
Assignment In Class: Classify Workbook Pages 105 & 106 Homework: Balance Workbook Pages 105 & 106 Classify Workbook Pages 107 & 108