4 8 Chapter 4 Part 2 Aqueous Reactions This section of the notes includes Sections 4 4 4 8 in the Tro textbook Section 4 9 will not be covered until next semester Molarity and Solution Stoichiometry Molarity M is used to describe solution concentration because it is very easy to determine Molarity This quickly gives us the number of moles of solute mol solute n Four things to know about molarity 1 M x V 2 Molarity can be used as a in stoichiometry problems 3 You can always replace M with For example 0 25 M HNO3 4 An Important Molarity Shortcut Solution by dilution 4 9 Problems 1 What is the concentration of a solution of HCl that was prepared by diluting 5 00 mL of 12 0 M HCl to 150 0 mL 2 If 5 85 g of sodium chloride NaCl molar mass 58 5 g mol is dissolved in 100 mL of solution what is the concentration of the solution expressed in molarity 3 How many moles of HCl are present in 320 mL of 0 250 M HCl 4 How many L of 0 100 M HCl are required to completely react with 13 0 g of MgCO3 in the following reaction MgCO3 s 2HCl aq MgCl2 aq H2O l CO2 g Electrolytes 1 Be sure to review 1 Names formulas and charges of all ions 2 These terms solution solvent solute aqueous solutions 2 Light bulb demonstration Figure 4 11 p 147 Figure 4 14 p 148 In the light bulb demonstration what happens in solution to cause some solutions to conduct electricity Before answering that question a more fundamental question is What is electric current Based on that definition substances that in aqueous solutions will conduct electricity 3 Principle When compounds dissolve in water they into ions NaCl aq NaNO3 aq 4 Principle Some compounds form ions when they dissolve in water called HCl aq 4 10 HNO3 aq CH3COOH aq NH3 aq H2O l 5 Definition of electrolyte 6 Strong electrolytes definition in practice how to identify 7 Weak electrolytes definition in practice how to identify 8 Nonelectrolytes examples 9 Memorize the seven strong acids 4 11 10 Memorize the strong bases 11 Two ways to define salt Precipitation Reactions 1 AgNO3 aq NaCl aq This is a or double displacement reaction Precipitation reaction What is the driving force of this reaction 2 To analyze reactions such as this it helps to write the equation in 3 different ways 1 molecular eqn 2 total ionic eqn 3 net ionic eqn 4 12 3 A net ionic equation is very important because 1 2 4 The driving force of a precipitation reaction is 5 A very important learning objective Know i e memorize the solubility rules and use them to predict if an ionic compound is soluble or insoluble Also use them to predict if a precipitation reaction will occur Solubility Rules Soluble Ionic Compounds Insoluble Ionic Compounds Examples Determine if the compounds below are soluble or insoluble in water AgCl Al OH 3 Na3PO4 Sr OH 2 CuSO4 Zn NO3 2 Cu OH 2 Ba ClO4 2 4 13 6 Be able to predict if a precipitation reaction will occur a What happens when aqueous solutions of barium nitrate and potassium sulfate are mixed molecular eqn total ionic eqn net ionic eqn b What happens when aqueous solutions of sodium chloride and potassium carbonate are mixed molecular eqn total ionic eqn net ionic eqn c What happens when aqueous solutions of ammonium carbonate and silver acetate are mixed molecular eqn total ionic eqn net ionic eqn d What happens when aqueous solutions of copper II sulfate and ammonium sulfide are mixed molecular eqn total ionic eqn net ionic eqn Acid Base Reactions 1 Metathesis reactions 2 Two important types of metathesis reactions 1 2 4 14 3 An acid is 4 A base is 5 Strong acids and bases 6 Weak acids and bases 7 Be able to write and balance acid base reactions a hydrochloric acid sodium hydroxide molecular eqn total ionic eqn net ionic eqn b perchloric acid strontium hydroxide molecular eqn total ionic eqn net ionic eqn c hydrofluoric acid potassium hydroxide molecular eqn total ionic eqn net ionic eqn Solution Stoichiometry 1 What volume of 0 100 M MgCl2 solution is required to precipitate all of the silver from 10 0 mL of 0 0500 M AgNO3 2 4 15 What mass of calcium carbonate is formed when 25 0 mL of 0 120 M calcium nitrate is mixed with 30 0 mL of 0 110 M potassium carbonate 3 If 28 5 mL of 0 100 M nitric acid is required to completely neutralize 21 0 mL of a solution of potassium hydroxide what is the concentration of the potassium hydroxide solution 4 What volume of 0 125 M hydrobromic acid is required to completely neutralize 25 0 mL of 0 0500 M calcium hydroxide 5 4 16 What is the concentration of chloride ions in a solution formed by mixing 50 0 mL of 0 100 M MgCl2 with 20 0 mL of 0 150 M FeCl3