Chapter 8 Outline 8.1 – Chemical Equations The symbols and formulas used to represent reactants and products

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:

Reading and Writing Chemical Equations: Metals are the symbol only: Magnesium metal = Mg Copper metal = Cu **No numbers or charges!!**

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.

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

Types of Equations Formula Equation Uses Formulas Example: CH 4 + O 2  CO 2 + H 2 O

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

Other Symbols s = solid l = liquid g = gas aq = aqueous = dissolved in water Reversible Reaction Add Heat

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.

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

Water  Hydrogen Gas + Oxygen Gas H2OH2O  H2H2 + O2O2

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

Water  Hydrogen Gas + Oxygen Gas H2OH2O O2O2  + H2H2 H O Count atoms to check!

Practice Problems

More Practice Problems

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

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

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!!

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)

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 

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

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

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

Solubility Solubility = Ability to dissolve Soluble = Dissolves In Water = Aqueous – aq Insoluble = Does NOT Dissolve Solid = s = precipitate

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**

Solubility Examples: Cu(NO 3 ) 2 = 2NaI ( ) + HgCl 2( )  2NaCl ( ) + HgI 2 ( )