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Chapter 8 Outline 8.1 – Chemical Equations The symbols and formulas used to represent reactants and products
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Reading and Writing Chemical Equations: 1. Represent the Facts 2. Use correct formulas for compounds: Ionic – SWAPPING Molecular – PREFIXES Diatomics – AUTOMATICALLY get a subscript “2” Silly Phrase:
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Reading and Writing Chemical Equations: Metals are the symbol only: Magnesium metal = Mg Copper metal = Cu **No numbers or charges!!**
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Reading and Writing Chemical Equations: 3. Law of Conservation of Mass: Nature balances the reactions, so we must too! We will use COEFFICIENTS which match what nature does.
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Types of Equations Word Equation Shows reactants and products in WORDS For now these will be given to you Example: Methane Gas + Oxygen Gas Carbon dioxide + Water
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Types of Equations Formula Equation Uses Formulas Example: CH 4 + O 2 CO 2 + H 2 O
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Types of Equations Balanced Equation Number of each atom on the left matches the number on the right THIS IS WHAT NATURE DOES! Example: CH 4 + 2O 2 CO 2 + 2H 2 O
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Other Symbols s = solid l = liquid g = gas aq = aqueous = dissolved in water Reversible Reaction Add Heat
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Significance of an Equation Will give us information about the amounts of reactants and products That’s Chapter 9! Reversible Reactions – Can proceed in either direction.
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Balancing Reactions Most can be done by inspection STEPS: 1. Write the WORD EQUATION (for now given) Ex. Water Hydrogen Gas + Oxygen Gas 2. Replace words with formulas
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Water Hydrogen Gas + Oxygen Gas H2OH2O H2H2 + O2O2
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3. Balancing Balance one atom at a time Start with elements that are on each side one time only Balance polyatomics (like NO 3 ) as an entire group when possible Balance O and H last
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Water Hydrogen Gas + Oxygen Gas H2OH2O O2O2 + H2H2 H O Count atoms to check!
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Practice Problems
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More Practice Problems
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8.2 – Types of Reactions 1. Synthesis Combining 2 or more reactants to form one product A + X AX Example: Magnesium + Oxygen Gas Magnesium oxide
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8.2 – Types of Reactions 2. Decomposition Breaking down 1 reactant into 2 or more products AX A + X Example: Silver oxide Silver metal + Oxygen gas Hydrogen peroxide Water + Oxygen gas
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8.2 – Types of Reactions 3. Single Displacement One element replacing another in a compound A + BX B + AX A replaces the one it is most similar to! Example: Iron + Copper (II) sulfate Copper + Iron (II) sulfate Honors: You must be able to predict products!!
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8.2 – Types of Reactions 4. Double Displacement Two elements switch places in compounds AX + BY AY + BX Example: Sodium chloride + Silver(I) nitrate Sodium nitrate + Silver(I) chloride 4 Types of Reactions Review: (Stop after Dbl Disp)
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8.2 – Types of Reactions 4. Double Displacement You must be able to predict products for this type of reaction! Example: Iron (II) sulfide + Hydrogen chloride
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Activity Series Activity = Ability to react Activity Series = List of elements by activity High on the list means the element can replace those below it Helps us determine whether a reaction will or will not happen
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Activity Series Li K Ca Na Mg Al Zn Fe Co Ni Sn Pb Cu Hg Ag Most active on this list Least active on this list
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Activity Series Li K Ca Na Mg Al Zn Cr Fe Co Ni Sn Pb Cu Hg Ag For a single displacement reaction to occur, the SINGLE REACTANT must be HIGHER than the one in the compound Example: 2Al + 3ZnCl 2 -> 3Zn + 2AlCl 3 Example: Co + 2NaCl -> CoCl 2 + 2Na
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Solubility Solubility = Ability to dissolve Soluble = Dissolves In Water = Aqueous – aq Insoluble = Does NOT Dissolve Solid = s = precipitate
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Solubility Solubility Rules (these will be given to you on test): Group 1 and Ammonium compounds ARE soluble Acetate, Nitrate, and chlorate compounds ARE soluble Group 17 (other than F) ARE soluble EXCEPT when with Ag, Hg2+2, and Pb Sulfates ARE soluble EXCEPT when with Ba, Sr, Pb, Ca, Ag, Hg2+2 Carbonates, Hydroxides, Oxides, Sulfides, Phosphates, Oxalates are INSOLUBLE **Start at the top and work down. STOP when you hit the first rule that applies to ANY PART of you compound**
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Solubility Examples: Cu(NO 3 ) 2 = 2NaI ( ) + HgCl 2( ) 2NaCl ( ) + HgI 2 ( )
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