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Reaction Types. How do we know what will be produced in a chemical reaction?. Recognizing a pattern of reactivity gives a broader understanding than memorizing a large number of reactions Would expect elements of the same family to behave similar 2K + 2H 2 O → 2KOH + H 2
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How do we know what will be produced in a chemical reaction? • Recognizing a pattern of reactivity gives a broader understanding than memorizing a large number of reactions • Would expect elements of the same family to behave similar • 2K + 2H2O → 2KOH + H2 • What will happen if Na combines with water?
Five Types of Reactions • Combustion – rapid reaction that produces flame • Occurs in hydrocarbons (compounds of C, H, and sometimes O) • Reaction of hydrocarbon with oxygen to produce carbon dioxide and water • C3H8 + 5O2 → 3CO2 + 4H2O • 2CH3OH + 3O2 → 2CO2 + 4H2O
Combination or Synthesis • Two reactants combine to form a single product • A + B → AB • Examples • C + O2→ CO2 • N2 + 3H2→ 2NH3 • CaO + H2O → Ca(OH)2
Decomposition • Single reactant breaks apart to form two or more substances • AB → A + B • Examples • 2KClO3 → 2KCl + 3O2 • CaCO3 → CaO + CO2
Single Replacement • One element replaces another similar element in a compound • A + BX → AX + B • Examples • Fe + 2HCl → FeCl2 + H2 • Zn + CuSO4 → ZnSO4 + Cu • Na + 2H2O → 2NaOH + H2
Double Replacement • Atoms exchange partners • Also called metathesis reactions • AX + BY → AY + BX • We will look at two types of double replacement • Acid-base reactions • Precipitation reactions
Acid-Base Reactions • Acid – substance that increases the H+ concentration in aqueous solutions • HCl → H+ + Cl- • H2SO4→ H+ + HSO4- • HSO4→ H+ + SO42-
Base • Increases the OH- concentration • NaOH → Na + OH- • NH3 + H2O → NH4+ + OH-
Neutralization • Acids and bases react together to produce a salt (ionic compound) and water • HCl + NaOH → NaCl + H2O • Write a balanced equation for the reaction of hydrobromic acid, HBr, with barium hydroxide, Ba(OH)2.
Write the balanced equation for the reaction between phosphoric acid, H3PO4, and potassium hydroxide.
Precipitation Reaction • Double replacement that forms a precipitate • KI (aq) + Pb(NO3)2 (aq) → PbI2 (s) + 2KNO3 (aq)
Example • When sodium phosphate and barium nitrate are mixed, a precipitate of barium phosphate forms. Write the balanced equation.
Example • When aqueous sodium hydroxide and magnesium nitrate are mixed, a magnesium hydroxide precipitate forms. Write the balanced chemical equation.