There’s a Quiz in Lab Next Week!!!

Wait – There’s a study guide

What about this quiz?? End of C 3 (section 3.7) Chapter 4 (except (4.4 – oxidation reduction pages 128-133 and titrations pages 140-143 Should bring a calculator and a pencil Think

Top 4 Topics Limiting reactants Ionic compounds in water Strong/weak acids & bases Molarity

Limiting Reactants Theoretical Yield % Yield = (Actual/Theoretical) x 100 How much is used, formed, left over

Ionic Compounds In water Strong / weak electrolytes Ionic equations Metathesis reactions Ion Solubility

Strong acids & bases Strong acids/bases are strong electrolytes Common strong acids (Table 4.2) (memorize) HCl HBr HI HClO3(chloric) HClO4 (perchloric) HNO3 H2SO4 Common strong bases Group I metal hydroxides (LiOH, NaOH, KOH, RbOH, CsOH) Heavy Group II metal hydroxides Ca(OH)2, Sr(OH)2 Ba(OH)2

Weak acids & bases Weak acids/bases are weak electrolytes An acid or base that is not strong is weak Examples of weak acids: HF H3PO4 H2SO3 HC7H5O2 HC2H3O2 Example of a weak base: NH3 A molecular substance that is not an acid or base is a nonelectrolyte

Molarity Interconverting molarity, moles, volume Dilution

Top 4 Topics Let’s do some examples! Limiting reactants Ionic compounds in water Strong/weak acids and bases Molarity

Limiting Reactants Theoretical Yield – how much you expect based upon the amount of reactants. If one reactant is present in excess, then the other limits how much can be made and is used to determine the theoretical yield.

2H2 + O2  2 H2O If 10 moles of oxygen and 10 moles of hydrogen…. The hydrogen limits the amount of water that can be formed Based upon 10 moles H2, we can make 10 moles water Based upon 10 moles O2, we can make 20 moles water. H2 limits. Theoretical Yield = 10 moles ( 180 g) H2O At end of reaction, will have 5 moles O2 left over

Ionic Compounds In water Strong / weak electrolytes Ionic equations Metathesis reactions Ion Solubility

Group 1A ( alkali metals) cations soluble NH4+ soluble NO3- soluble CH3CO2- = C2H3O2- = acetate soluble Will be given a chart for other ions

Soluble ionic compounds in water exist as free ions surrounded by water molecules. Soluble ionic compounds are strong electrolytes Strong acids or bases (HCl, H2SO4), NaOH) are strong electrolytes Weak acids or bases (CH3CO2H, acetic acid) are weak electrolytes Molecules that do not disassociate (CO2, sugar) are non electrolytes.

What kind of electrolyte am I? (NH4)2SO4 ? Strong HF Weak C12H22O11 (sucrose) Non NH3

potassium sulfate with barium nitrate 2K+(aq) + SO4-2 (aq) + Ba+2 (aq) + 2 NO3- (aq)  2K+(aq) + 2 NO3- (aq) +BaSO4(s) SO4-2 (aq) + Ba+2 (aq)  BaSO4(s)

Molarity Interconverting molarity, moles, volume M means moles per liter = moles/L M = moles/L If you know two things, can determine the third If you have moles and volume, can determine molarity 3 moles dissolved in 0.5 L = 3moles/0.5L = 6M

(Vconc )(Mconc ) = (Vdil )(Mdil ) Molarity - dilution (Vconc )(Mconc ) = (Vdil )(Mdil ) If you know 3, can solve for the fourth How many mL of 3M HCl is needed to make 100mL of 1.5 M HCl? (Vconc)(3M) = (100mL)(1.5M) Vconc = 50 mL