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Chapter 8 (cont.)

Chapter 8 (cont.). TYPES OF REACTIONS- patterns observed empirically allow prediction of products when reactants are known. SYNTHESIS. More complex product made from simpler substances General format : A + X → AX element + element → compound EX: Sodium + chlorine →

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Chapter 8 (cont.)

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  1. Chapter 8 (cont.) TYPES OF REACTIONS- patterns observed empirically allow prediction of products when reactants are known

  2. SYNTHESIS • More complex product made from simpler substances • General format : A + X → AX element + element → compound • EX: • Sodium + chlorine → • Magnesium + nitrogen → • Sodium + oxygen →

  3. DECOMPOSITION • A single reactant is broken down into simpler substances • AX → A + X • CMPD → ELEMENT + ELEMENT Most require an input of energy to break the bonds in the reactants. • EX: water → • magnesium bromide →

  4. SINGLE REPLACEMENT REACTIONS • An element on its own pushes another SIMILAR element out of a cmpd (replaces it) • An element can only be replaced by a more active element. Check activity series to decide if rxn will occur. • A + BX → AX + B element + cmpd → different cmpd + diff. elem. Ex: Al (s) + CuCl2 → OR: Y + BX → BY + X Ex: Cl2 + NaBr →

  5. Examples: • iron is added to a solution of silver nitrate (assume Fe3+) • A piece of sodium is dropped into water • Fluorine is bubbled into a solution of potassium iodide

  6. Single Replacement (cont.) • Moreactive metals get oxidized (give up electrons more easily to form positive ions), • less active metals will accept them-get reduced • LEO GER • Atoms of uncombined elements have 0 oxidation number. • More activenonmetals gain electrons (get reduced) more easily & form negative ions • Reactions where e-’s are transferred can be classified as oxidation-reduction or redox reactions.

  7. DOUBLE REPLACEMENT REACTIONS • “IONS SWITCH PARTNERS” • AX + BY → AY + BX Cmpd + cmpd → two different compounds • Precipitation Rxns • One product is soluble, the other is not • Use solubility rules to determine if there is a precipitate EX: NaCl (aq) + AgCH3COO (aq) →

  8. 1. Precipitation Rxns (cont) • Ex: Solutions of barium nitrate and sodium sulfate are combined: • Solutions of lithium sulfate and magnesium bromide are combined.

  9. 2. Acid/Base Neutralization • Acid + base → salt + water (H+) (OH-) • nitric acid + lithium hydroxide → • sulfuric acid + potassium hydroxide → • Acetic acid + barium hydroxide →

  10. Net Ionic Equations • Formula Unit Equation- normal balanced equation including states (NH4)2S(aq) + Cd(NO 3)2 (aq) → 2. Total Ionic Equation – all aqueous substances are separated into ions. Note: polyatomic ions stay together as a group. Cancel all spectator ions 3. Net ionic equation- rewrite remaining equation w/states

  11. Combustion Reactions • Hydrocarbon + oxygen → carbon dioxide + water CxHy + O2→ CO2 + H2O Ex: Liquid decane, C10H22 , is burnt in air

  12. Ammonium dichromate (Cr2O72-) decomposes with heating into chromium (III) oxide, nitrogen, and water vapor. • White phosphorus (P4) ignites spontaneously in air to form solid tetraphosphorus decaoxide.

  13. Ammonium nitrate is used as a fertilizer even though it can be explosive. It can be made by bubbling ammonia gas (NH3) through a solution of nitric acid. • An electric current is passed through a sodium chloride solution and forms sodium hydroxide, chlorine and hydrogen. The water in the solution participates in the reaction.

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