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Chapter 13 Properties of Liquids Foundations of College Chemistry, 13e

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1 Chapter 13 Properties of Liquids Foundations of College Chemistry, 13e
Liquid water provides the base for the recreation of windsurfing and also for our bodies., Water is a unique liquid on our blue planet. Foundations of College Chemistry, 13e John Wiley & Sons, Inc Morris Hein and Susan Arena

2 Chapter Outline 13.1 What is a Liquid? 13.2 Evaporation
13.3 Vapor Pressure 3/25/2017 C Properties of Liquids Solutions Acids Bases Salts Copyright 2011 John Wiley & Sons, Inc

3 What Is a Liquid? 3/25/2017 C Properties of Liquids Solutions Acids Bases Salts Copyright 2011 John Wiley & Sons, Inc

4 Evaporation Evaporation or vaporization is the escape of molecules from the liquid state to the gas or vapor state. liquid  vapor 3/25/2017 C Properties of Liquids Solutions Acids Bases Salts Copyright 2011 John Wiley & Sons, Inc

5 Sublimation Sublimation is the phase change from the solid state to the gas or vapor state without going through the liquid state. solid  vapor CO2(s)  CO2(g) I2(s)  I2(g) Iodine crystals 3/25/2017 C Properties of Liquids Solutions Acids Bases Salts Copyright 2011 John Wiley & Sons, Inc

6 Vapor Pressure In a closed container, an equilibrium develops where there are as many molecules evaporating as there are condensing. Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid. Figure 13-3 (a) Molecules in an open flask evaporate in the atmosphere. (b) When the flask is stoppered the number of gaseous molecules increases inside the flask. Some gasous molecules collide with the surface of the liquid and stick – condensation occurs. (c) When the rate of evaporation equals the rate of condensation, an equilibrium between the liquid and vapor is established. liquid vapor evaporation condensation 3/25/2017 C Properties of Liquids Solutions Acids Bases Salts Copyright 2011 John Wiley & Sons, Inc

7 Vapor Pressure Is independent of the quantity of the liquid or its surface area Increases with increasing temperature. Depends on the strength of the attraction between molecules in the liquid state. Volatile liquids have very weak attractive forces and so evaporate rapidly at room temperature. Volatile liquids have high vapor pressures at 25°C. 3/25/2017 C Properties of Liquids Solutions Acids Bases Salts Copyright 2011 John Wiley & Sons, Inc

8 Vapor Pressure Figure 13.4 (a) A barometer measures atmospheric pressure. To measure the vapor pressure of a liquid a tiny amount is injected into the barometer. (b) The water vapor presses the Hg down 24 mm (vapor pressure = 24 mm Hg) (c) Ethyl alcohol presses the Hg level down 44 mm (vapor pressure = 44 mm Hg) (d) Diethyl ether has a vapor pressure of 318 mm Hg 3/25/2017 C Properties of Liquids Solutions Acids Bases Salts Copyright 2011 John Wiley & Sons, Inc

9 Your Turn! The vapor pressure of diethyl ether was 318 mm Hg while the vapor pressure of ethyl alcohol was 44 mm Hg. Which substance has stronger attractive forces between molecules? diethyl ether ethyl alcohol 3/25/2017 C Properties of Liquids Solutions Acids Bases Salts Copyright 2011 John Wiley & Sons, Inc

10 Your Turn! In a system at equilibrium between the liquid and gas phases Particles stop changing phase The rate at which particles change from liquid to gas exceeds the rate at which they change from gas to liquid. The rate at which particles change from gas to liquid equals the rate at which they change from liquid to gas. 3/25/2017 C Properties of Liquids Solutions Acids Bases Salts Copyright 2011 John Wiley & Sons, Inc

11 Your Turn! Which has the lowest vapor pressure?
100 mL of gasoline at 15°C 25 mL of gasoline at 50°C 50 mL of gasoline at 50°C 25 mL of gasoline at 70°C 3/25/2017 C Properties of Liquids Solutions Acids Bases Salts Copyright 2011 John Wiley & Sons, Inc

12 Chapter 14 Solutions Foundations of College Chemistry, 13e
Brass, a solid solution of zinc and copper, is used to make musical instruments and many other objects. Foundations of College Chemistry, 13e John Wiley & Sons, Inc Morris Hein and Susan Arena

13 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Chapter Outline 14.1 General Properties of Solutions 14.2 Solubility 14.3 Factors Related to Solubility 14.4 Rate of Dissolving Solids 14.5 Solutions: A Reaction Medium 14.6 Concentration of Solutions 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

14 General Properties of Solutions
A solution is a homogeneous mixture of one or more solutes and the solvent. The solute is the substance being dissolved. The solvent is the dissolving agent and is usually the most abundant substance in the mixture. Air is a solution of N2(g), O2(g), Ar(g), CO2(g)... What substance is the solvent in air? N2(g), since 78% of air is N2. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

15 Common Types of Solutions
What gas is the solute in soft drinks? carbon dioxide What is another solute in soft drinks? sugar and flavorings 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

16 Properties of a True Solution
A homogeneous mixture of 2 or more components whose ratio can be varied. The dissolved solute is molecular or ionic in size (less than 1 nm). Liquid or gaseous solutions can be colored or colorless and are usually transparent. The solute will not settle out of the solution. The solute can be separated from the solvent by physical means. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

17 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Your Turn! Sweet tea is prepared by dissolving an instant tea packet in water. Which substance is the solvent? sugar tea water 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

18 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Your Turn! A solution of alcohol and water is prepared by adding 25 mL of water to 75 mL methyl alcohol. Which substance is the solute? methyl alcohol water 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

19 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Solubility Solubility describes the amount of a substance that will dissolve in a specified amount of solvent at a particular temperature. For example: 36 g NaCl/100 g H2O at 20°C Miscible is the term used if 2 liquids will dissolve in each other. Immiscible is used if the liquids will not dissolve in each other. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

20 Ionic Compound Solubility Rules
NaCl soluble AgNO3 AgCl insoluble AgOH 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

21 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Your Turn! Use the ionic compound solubility rules to predict the solubility of barium sulfate. soluble insoluble 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

22 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Your Turn! Use the ionic compound solubility rules to predict the solubility of ammonium carbonate. soluble insoluble 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

23 Factors Related to Solubility
“Like dissolves like” Polar compounds dissolve in polar solvents, like water and alcohol (CH3CH2OH) Acetone [(CH3)2CO] dissolves in water because it has a net dipole on the O to C bond, making it polar. Nonpolar compounds dissolve in nonpolar solvents, like petroleum ether and CCl4 Hexane [CH3(CH2)4CH3] dissolves in petroleum ether because they are both nonpolar. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

24 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Ionic Solubility Many ionic compounds dissolve in water because they form ion to dipole forces with water (a strong intermolecular force). The ions become surrounded by water (become hydrated). The cation is attracted to the partially negative O in water The anion is attracted to the partially positive H in water. Figure 14.3 Dissolution of sodium chloride in water. Polar water molecules are attracted to Na and Cl- ions in the salt crystal, weakening the attraction between the ions. As the attraction between the ions weakens, the ions move apart and become surrounded by water dipoles. The hydrated ions slowly diffuse away from the crystal to become dissolved in solution. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

25 Temperature and Solubility
Most solids’ solubility increases with increasing temperature. (See red lines.) All gases solubility decreases with increasing temperature. (See blue lines.) Figure 14.4 Solubility of various compounds in water. Solids are shown in red and gases are shown in blue. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

26 Pressure and Solubility
Pressure does not affect the solubility of solids or liquids, but there is a large effect with gases. The solubility of gas in a liquid is proportional to the pressure of the gas over the liquid. Sodas are canned under high pressure. When you open a can, the pressure decreases and bubbles form, releasing the excess gases. Pouring root beer into a glass illustrates the effect of pressure on solubility. The escaping carbon dioxide produces the foam. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

27 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Your Turn! Under what conditions are gases most soluble in liquids? high temperature, high pressure high temperature, low pressure low temperature, high pressure low temperature, low pressure 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

28 Saturated and Unsaturated Solutions
Saturated solutions contain as much dissolved solute as the solvent will hold at a given temperature. Saturated solutions are always in equilibrium with undissolved solute. undissolved solute dissolved solute Any point on the solubility curve represents a saturated solution of that solute. Unsaturated solutions contain less solute than the amount needed to saturate the solution. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

29 Supersaturated Solutions
Supersaturated solutions contain more solute than the amount needed to saturate the solution at a particular temperature. Supersaturated solutions are unstable – stirring, adding a crystal of solute – will cause the excess solute to come out of solution. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

30 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Your Turn! What mass of this compound will dissolve at 30°C? 5.0 g 5.4 g 5.8 g 6.0 g 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

31 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Your Turn! 6.0 g of solute is dissolved in 100 g of water at 60°C. The solution is allowed to cool to 25°C. No crystals form. The solution is: saturated unsaturated supersaturated 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

32 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Your Turn! The addition of a crystal sodium acetate to a sodium acetate solution causes additional crystals of sodium acetate to precipitate. The original solution was Saturated Supersaturated Unsaturated 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

33 Rate of Dissolving Solids
Particle Size A solid can dissolve only at the surface that is in contact with the solvent. Smaller crystals have a larger surface to volume ratio than large crystals. Smaller crystals dissolve faster than larger crystals. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

34 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Surface Area 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

35 Rate of Dissolving Solids
Temperature Increasing the temperature increases the rate at which most compounds dissolve. This occurs because solvent molecules strike the surface of the solid more frequently, causing the solid to dissolve more rapidly. The dissolved solute particles are also carried away from the solid by the higher kinetic energy solvent molecules, allowing more solvent to hit the surface. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

36 Rate of Dissolving Solids
Concentration of solution 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

37 Rate of Dissolving Solids
Agitation or Stirring Stirring rapidly distributes the dissolved solute throughout the solution, eliminating the saturated solution that forms at the surface of the solid. Moving dissolved solute away from the surface increases the contact between water molecules and the solid and increases the rate of dissolving. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

38 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Your Turn! Which would most likely increase the solubility of a solid in water? Stirring Grind the solid to increase its surface area Increase the pressure Increase the temperature All of the above 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

39 Solutions: A Reaction Medium
Dissolving reactants allows them to come into solution. Combining two solids usually will not result in any significant reaction: KCl(s) + AgNO3 (s)  no reaction But if you dissolve those same reactants in water, the silver ion can collide with the chloride ion, resulting in solid AgCl. KCl(aq) + AgNO3(aq)  AgCl(s) + KNO3(aq) 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

40 Concentration of Solutions
Qualitative expressions of concentration: A dilute solution contains a relatively small amount of dissolved solute. A concentrated solution contains a relatively large amount of solute. Hydrochloric acid is sold as a concentrated 12 M (moles/ L) solution. A dilute 0.1 M solution is commonly found in labs. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

41 Concentration of Solutions
Quantitative expressions of concentration: 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

42 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Mass Percent Calculate the mass % NaCl in a solution prepared by dissolving 50. g NaCl in 150. g H2O. 50. g NaCl (solute) 150. g H2O (solvent) 50. g NaCl g H2O = 200. g mass of solution Knowns Solving for Calculate = 25% NaCl 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

43 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Mass Percent Calculate the mass of Na2CO3 and water needed to make 350. g of a 12.3% solution. 350. g solution 12.3% solution Knowns Solving for mass of solute (Na2CO3) and mass of H2O Calculate = 43.1 g Na2CO3 mass of H2O = 350. g – 43.1 g = 307 g H2O 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

44 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Mass-Volume Percent Normal saline is a 0.90 m/v % NaCl solution. What mass of sodium chloride is needed to make 50. mL of normal saline? 50. mL solution 0.90 m/v% solution Knowns Solving for mass of solute (NaCl) Calculate = 0.45 g NaCl 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

45 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Volume Percent What volume of beer that is 6.0 % by volume alcohol contains 200. ml CH3CH2OH (ethyl alcohol)? Knowns 200. mL EtOH (solute) 6.0 volume % solution Solving for volume of solution volume of solution = 3.3 L beer Calculate 200 mL EtOH 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

46 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Your Turn! A 20.0 % solution of KCl has a mass of 400. g. What mass of KCl is contained in this solution? 20.0 g 80.0 g 320. g 400. g 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

47 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Your Turn! A solution is prepared by mixing 20.0 mL of propanol with enough water to produce mL of solution. What is the volume percent of propanol in this solution? A % B % C % D % 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

48 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Molarity A 1.0 M KCl solution is prepared by dissolving 1.0 moles KCl in enough water to make 1.0 L of solution. 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

49 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Molarity Calculate the molarity of a solution prepared by dissolving 9.35 g KCl in enough H2O to make 250. mL solution. 9.35 g KCl (solute) 250. mL solution Knowns Solving for = M KCl Calculate 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

50 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Dilution Dilution: Adding solvent to a concentrated solution to make a more dilute solution. When you dilute a concentrated solution, only the volume of solution changes. The quantity of solute remains the same. Volume (V) × Molarity (M) = moles of solute V1 × M1 = V2 × M2 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

51 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Dilution V1 × M1 = V2 × M2 How many milliliters of 12 M HCl are needed to make 500. mL of 0.10 M HCl? 12 M HCl (concentrated solution) M1 0.10 M HCl (dilute solution) C2 500. mL (dilute solution) V2 Knowns volume of 12 M HCl V1 Solving for Calculate 4.2 mL of 12 M HCl 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

52 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Your Turn! What is the molarity of a solution in which 5.85 g of NaCl is dissolved in 200. mL of solution? 0.500 M 1.00 M 2.00 M 4.00 M 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

53 C14 Solutions Copyright 2011 John Wiley & Sons, Inc
Your Turn! What is the molarity of the resulting solution when 300. mL of a M solution is diluted to 800. mL? 0.109 M 0.150 M 1.07 M 1.47 M 3/25/2017 C14 Solutions Copyright 2011 John Wiley & Sons, Inc

54 Chapter 15 Acids, Bases, and Salts
Lemons and limes are examples of food which contains acidic solutions. Foundations of College Chemistry, 13e John Wiley & Sons, Inc Morris Hein and Susan Arena

55 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Chapter Outline 15.1 Acids and Bases 15.2 Reactions of Acids 15.3 Reactions of Bases 15.4 Salts 15.5 Electrolytes and Nonelectrolytes 15.6 Dissociation and Ionization of Electrolytes 15.7 Strong and Weak Electrolytes Ionization of Water Introduction to pH 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

56 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Arrhenius Acids Definition: An acid solution contains an excess of H+ ions. Properties Sour taste Turn blue litmus red The ability to react with Metals to produce H2 gas Bases to produce salt and water Carbonates to produce carbon dioxide 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

57 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Arrhenius Bases Definition: A base solution contains an excess of OH- ions. Properties Bitter or caustic taste Turn red litmus blue Slippery, soapy feeling Neutralize acids 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

58 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Your Turn! Which type of solution would have a sour taste and turn blue litmus red? Acid Base Salt 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

59 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Reactions of Acids Acids react with metals that lie above H in the activity series: acid + metal  salt + hydrogen 2HCl(aq) + Mg(s)  MgCl2(aq) + H2(g) Acids react with bases (neutralization) acid + base  salt + water 2HCl(aq) + Ca(OH)2(aq) CaCl2(aq) + 2H2O (l) 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

60 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Reactions of Acids Acids react with metal oxides acid + base  salt + water 2HCl(aq) + Na2O(s)  2NaCl(aq) + H2O(l) Acids react with metal carbonate acid + base  salt + water + carbon dioxide 2HCl(aq) + Na2CO3(aq) 2NaCl(aq) + H2O(l) + CO2(g) 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

61 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Reactions of Bases Bases can be amphoteric as base: Zn(OH)2(aq)+ 2HBr(aq)  ZnBr2(aq) + 2H2O(l) as acid: Zn(OH)2(aq)+ 2NaOH(aq)  Na2Zn(OH)4(aq) NaOH and KOH react with metals base + metal + water  salt + hydrogen 2NaOH(aq) + 2Al(s) + 6H2O(l)  2NaAl(OH)4(aq) + 3H2O(g) 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

62 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Your Turn! What gas is produced by the reaction of sodium bicarbonate with acetic acid? Hydrogen Carbon dioxide Nitrogen Oxygen 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

63 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Salts are the result of acid-base neutralization reactions. HCl(aq)+ NaOH(aq) NaCl(aq)+ H2O(l) Salts are ionic compounds composed of a cation (usually a metal or the ammonium ion) and an anion (not oxide or hydroxide). Salts are usually crystals with high melting and boiling points. 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

64 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Your Turn! What salt forms from the reaction of magnesium hydroxide and sulfuric acid? MgS Mg2S MgSO4 Mg2SO4 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

65 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Your Turn! What salt forms from the reaction of aluminum oxide and hydrobromic acid? AlBr AlBr3 Al2Br Al2Br3 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

66 Electrolytes and Nonelectrolytes
Electrolytes are compounds whose aqueous solutions conduct electricity. Nonelectrolytes are substances whose aqueous solutions are nonconductors. 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

67 Electrolytes and Nonelectrolytes
It is the movement of ions that conduct electricity in water . Acids, bases and salts are electrolytes because they produce ions in water when they dissolve. 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

68 Dissociation of Electrolytes
Salts dissociate into cations and anions when they dissolve in water. NaCl(s)  Na+(aq) + Cl-(aq) 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

69 Ionization of Electrolytes
Ionization is the formation of ions; it is the result of the chemical reaction with water. Acids ionize in water, producing hydronium ions and anions. HCl(g) + H2O(l)  H3O+(aq) + Cl-(aq) H3PO4(aq) + H2O(l) H3O+(aq) + H2PO4-(aq) Weak bases ionize in water, producing hydroxide ions and cations. NH3(aq) + H2O(l) OH- (aq) + NH4+(aq) 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

70 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Your Turn! Which will not dissociate when placed in water? KBr HCl CH3OH HClO4 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

71 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Your Turn! A solution is tested with the conductivity apparatus and the light bulb did not light. Which of the following is not likely? The beaker contained only water. The beaker contained water and C6H12O6. The beaker contained water and CaCl2. All of the above are likely possibilities. 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

72 Strong and Weak Electrolytes
Strong electrolytes are essentially 100% ionized in water (HCl). Weak electrolytes are much less ionized (HC2H3O2). 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

73 Strong and Weak Electrolytes
Use double arrows to indicate weak ionization. HC2H3O2(aq) + H2O(l) H3O+(aq) + C2H3O2-(aq) HF(aq) + H2O(l) H3O+(aq) + F-(aq) 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

74 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Salts dissociate into at least 2 ions. A 1M solution of NaCl produces a 2M solution of ions. NaCl(s)  Na+(aq) + Cl-(aq) 1 mole 1 mole + 1 mole A 1M solution of CaCl2 produces a 3M solution of ions. CaCl2(s)  Ca2+(aq) + 2Cl-(aq) 1 mole 1 mole + 2 mole 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

75 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Your Turn! What is the concentration of chloride ion in a 2.0 M solution of calcium chloride? 1.0 M 2.0 M 3.0 M 4.0 M 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

76 Ionization of Water → Pure water auto-ionizes
H2O(l) + H2O(l) H3O+(aq) + OH-(aq) Concentration H3O+ = Concentration OH- = 1×10-7 M [H3O+]×[OH-] = 10-14 In acid solutions, [H3O+]>[OH-] In basic solution, [H3O+]<[OH-] 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

77 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Introduction to pH pH = -log[H+] In pure water, [H+] = 1×10-7 M so pH = -log(10-7) = 7 high H+ low OH- low H+ high OH- 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

78 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
pH 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

79 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Your Turn! How many times more acidic is a solution with a pH of 3 than a solution with a pH of 5? 2 20 200 100 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

80 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Introduction to pH pH = -log[H+] 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

81 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Introduction to pH Calculate the pH of a 0.015M H+ solution. pH = - log (0.015) = 1.82 Note: The digits to the left of the decimal place in the pH (the characteristic of the log) reflect the power of ten in the [H+]. In this case, the 1. The characteristic is NOT one of the significant figures in the pH. The number of decimal places for the mantissa of a log must equal the number of significant figures in the original number. 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

82 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Your Turn! What is the pH of a M hydrochloric acid solution? 0.020 -2.0 1.70 1.7 -1.7 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc

83 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc
Your Turn! What is the pH of a solution of sodium hydroxide that has a hydronium ion concentration of 2.5×10-11? 11 10.6 -10.60 10.60 3/25/2017 C15 Acids, Bases and Salts Copyright 2011 John Wiley & Sons, Inc


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