CHM1045 Lecture 11Outline of Last LectureI. Amount of Reactants and Productsi. Example 1ii. Example 2II. Limiting Reagenti. Example 3ii. Example 4III. Reaction Yieldi. Example 5Outline of Current LectureIV. Conduct electricity in solution?V. Ionization of acetic acidVI. Precipitation ReactionsVII. Precipitation of Lead Iodideii. Example 1I. Writing net ionic equationsiii. Example 2Current LectureChapter 4: Reactions in Aqueous Solutions- A solution is a homogenous mixture of 2 or more substances.- The solute is (are) the substance(s) present in the smaller amount(s).- The solvent is the substance present in the larger amount.Solution Solvent SoluteSoft drink H2O Sugar, CO2Air(G) N2 O2,Ar, CH4Soft solder (s) Pb Sn- An electrolyte is a substance that, when dissolved in water, results in a solution that can conduct electricity.- A nonelectrolyte is a substance that, when dissolved, results in a solution that does not conduct electricity.Conduct electricity in solution?- Cations (+) and Anions (-)- Strong Electrolyte – 100% dissociationNaCl (s) Na+ (aq) + Cl- (aq)- Weak Electrolyte – not completely dissociated- CH3COOH CH3COO- (aq) + H+ (aq) Ionization of acetic acid- CH3COOH CH3COO- (aq) + H+ (aq) - A reversible reaction. The reaction can occur in both directions.- Acetic acid is a weak electrolyte because its ionization in water is incomplete.- Hydration is the process in which an ion is surrounded by water molecules arranged in a specific manner.- Nonelectrolyte does not conduct electricity?- No cations (+) and anions (-) in solution- C6H12O6 (s) H2O C6H12O6 (aq)Precipitation Reactions- Precipitate – insoluble solid that separates from solution- Pb(NO3)2 (aq) + 2NaI (aq) PbI2 (s) + 2NaNO3 (aq)molecular equationPb2+ + 2NO3- + 2Na+ + 2I- PbI2 (s) + 2Na+ + 2NO3ionic equationPb2+ + 2I- PbI2 (s) net ionic equationNa+ and NO3- are spectator ionsPrecipitation of Lead IodidePb2+ + 2I- PbI2 (s)- Solubility is the maximum amount of solute that will dissolve in a given quantityof solvent at a specific temperatureExample 1.Classify the following ionic compounds as soluble or insoluble: (a) silver sulfate (Ag2SO4)(b) calcium carbonate (CaCO3)(c) sodium phosphate (Na3PO4).(a) insoluble(b) insoluble(c) Na3PO4Writing Net Ionic Equations1. Write the balanced molecular equation.2. Write the ionic equation showing the strong electrolytes completely dissociated into cations and anions.3. Cancel the spectator ions on both sides of the ionic equation.4. Check that charges and number of atoms are balanced in the net ionic equation.Example 2. Predict what happens when a potassium phosphate (K3PO4) solution is mixed with a calcium nitrate [Ca(NO3)2] solution. Write a net ionic equation for the reaction.The balanced equation:2K3PO4(aq) + 3Ca(NO3)2 (aq) Ca3(PO4)2(s) + 6KNO3 (aq)6K+ (aq) + 2PO3-4 (aq) + 3Ca2+(aq) + 6NO-3 (aq) 6K+ (aq) + 6NO-3(aq) + Ca3(PO4)2 (s)Canceling the spectator ions (K+ and NO-3) on each side of the equation, we obtain thenet ionic compound3Ca2+ (aq) + 2PO3-4 (aq) Ca3(PO4)2
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