chapter 12 solutions 12.1 types of mixtures. classification of matter solutions are homogeneous...
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Chapter 12Chapter 12
SolutionsSolutions
12.1 Types of Mixtures
Classification of MatterClassification of MatterSolutions are
homogeneous
mixtures!
SoluteSoluteA solute is the dissolved substance in a solution.
A solvent is the dissolving medium in a solution.
SolventSolvent
Salt in salt water
Sugar in soda drinks
Carbon dioxide in soda drinks
Water in salt water
Water in soda
Types of Solutions Types of Solutions
• Gaseous mixturesGaseous mixtures
Air is a solution Air is a solution
• Solid solutionsSolid solutions
Metal alloys Metal alloys
• Liquid solutions Liquid solutions
Liquid dissolved in a liquid Liquid dissolved in a liquid
(alcohol in water) (alcohol in water)
Solid dissolved in a liquidSolid dissolved in a liquid
(salt water) (salt water)
Concentrated vs. DiluteConcentrated vs. Dilute
Suspensions and ColloidsSuspensions and Colloids
Suspensions and colloids are NOT solutions.
Suspensions: The particles are so large that they settle out of the solvent if not constantly stirred. Particles can be filtered out.Example: Oil & Water
Colloids: The particles intermediate in size between those of a suspension and those of a solution. Particles cannot be easily filtered out.Example: Milk
Smoke is a solid in a
gas. Fog is a
liquid in a gas.
Milk of Magnesia is a sol with solid magnesium hydroxide in
water
Mayonnaise is oil in water
Gelatin is protein in
water. Quicksand is sand in
water
The Tyndall EffectThe Tyndall Effect
Colloids scatter light, making a beam visible. Solutions do not scatter light.
Which glass contains a colloid? solutioncolloid
The ammeter measures the flow of electrons (current) through the circuit.
If the ammeter measures a current, and the bulb glows, then the solution conducts.
If the ammeter fails to measure a current, and the bulb does not glow, the solution is non-conducting.
Electrolytes vs. NonelectrolytesElectrolytes vs. Nonelectrolytes
An electrolyte is: A substance whose aqueous solution conducts
an electric current.
A nonelectrolyte is:
A substance whose aqueous solution does not conduct an electric current.
Try to classify the following substances as electrolytes or nonelectrolytes…
Definition of Electrolytes and Definition of Electrolytes and NonelectrolytesNonelectrolytes
1. Pure water2. Tap water3. Sugar solution4. Sodium chloride solution5. Hydrochloric acid solution6. Lactic acid solution7. Ethyl alcohol solution8. Pure sodium chloride
Electrolytes?Electrolytes?
Electrolytes: Nonelectrolytes:
Tap water (weak)
NaCl solution
HCl solution
Lactate solution (weak)
Pure water
Sugar solution
Ethanol solution
Pure NaCl
But why do some compounds conduct electricity insolution while others do not…?
Chapter 12Chapter 12
SolutionsSolutions
12.2 The Solution Process
Dissolution of sodium ChlorideDissolution of sodium Chloride
The Hydration Process
Saturation of SolutionsSaturation of Solutions A solution that contains the maximum A solution that contains the maximum
amount of solute that may be dissolved amount of solute that may be dissolved under existing conditions is under existing conditions is saturatedsaturated..
A solution that contains less solute than a A solution that contains less solute than a saturated solution under existing saturated solution under existing conditions is conditions is unsaturatedunsaturated..
A solution that contains more dissolved A solution that contains more dissolved solute than a saturated solution under the solute than a saturated solution under the same conditions is same conditions is supersaturatedsupersaturated..
Factors Affecting the Rate of Factors Affecting the Rate of Dissolution Dissolution
• Increasing the Surface Area of the SoluteIncreasing the Surface Area of the Solute
Finely divided substances dissolve more rapidly Finely divided substances dissolve more rapidly
• Agitating a SolutionAgitating a Solution
Stirring or shaking brings solvent into contact with Stirring or shaking brings solvent into contact with more solute particles more solute particles
Added energy temporarily increases solubility Added energy temporarily increases solubility
• Heating Heating
Heating almost always increasing the rate of Heating almost always increasing the rate of dissolution of solids in liquids dissolution of solids in liquids
““Like dissolves like”Like dissolves like”
• Polar substances dissolve in polar solvents Polar substances dissolve in polar solvents • Nonpolar substances dissolve in nonpolar solvents Nonpolar substances dissolve in nonpolar solvents
• Examples:Examples:• Polar and ionic compounds are not soluble in Polar and ionic compounds are not soluble in
nonpolar solvents nonpolar solvents • Fats, oils and many petroleum products are soluble in Fats, oils and many petroleum products are soluble in
nonpolar solvents nonpolar solvents
• Nonpolar solvents include CClNonpolar solvents include CCl44 and toluene (methyl and toluene (methyl
benzene), Cbenzene), C66HH55CHCH33
• Liquid Solutes and SolventsLiquid Solutes and Solvents Immiscible - Liquid solutes and solvents that are Immiscible - Liquid solutes and solvents that are not soluble in each other not soluble in each other
Ex: Oil and waterEx: Oil and water Miscible - Liquids that dissolve freely in one Miscible - Liquids that dissolve freely in one another in any proportion another in any proportion
Ex: Benzene and carbon tetrachloride (both nonpolar) Ex: Benzene and carbon tetrachloride (both nonpolar) Ex: Water and ethanol (both polar) Ex: Water and ethanol (both polar)
• HydratesHydrates Ionic substances that incorporate water molecules Ionic substances that incorporate water molecules into their structure during the recrystallization into their structure during the recrystallization process process
Ex: CuSOEx: CuSO44•5H•5H22O O
Saturation and EquilibriumSaturation and Equilibrium
The physical state in which the opposing processes of dissolution and crystallization of a solute occur at equal rates
Effects of Pressure on SolubilityEffects of Pressure on Solubility • Pressure has no real effect on the solubilities of liquids Pressure has no real effect on the solubilities of liquids
and solids in liquid solvents and solids in liquid solvents • Increasing pressure increases the solubility of gases in Increasing pressure increases the solubility of gases in
liquids liquids
• Henry's Law Henry's Law • The solubility of a gas in a liquid The solubility of a gas in a liquid
is directly proportional to the is directly proportional to the partial pressure of that gas on the partial pressure of that gas on the surface of the liquid surface of the liquid
• Effervescence Effervescence • The rapid escape of a gas from a liquid in which it is The rapid escape of a gas from a liquid in which it is
dissolved dissolved
Effects of Temperature on SolubilityEffects of Temperature on Solubility
• Solubility of solids increases with temperature Solubility of solids increases with temperature • Solubility of gases decreases with temperature Solubility of gases decreases with temperature
Solubility TrendsSolubility Trends The solubility of MOST solids increases The solubility of MOST solids increases
with temperature.with temperature. The rate at which solids dissolve The rate at which solids dissolve
increases with increasing surface area of increases with increasing surface area of the solid.the solid.
The solubility of gases decreases with The solubility of gases decreases with increases in temperature.increases in temperature.
The solubility of gases increases with the The solubility of gases increases with the pressure above the solution.pressure above the solution.
Therefore…Therefore…Solids tend to dissolve best when:
o Heatedo Stirredo Ground into small particles
Liquids & Gases tend to dissolve best when:
o The solution is coldo Pressure is high
Heat of SolutionHeat of SolutionThe Heat of Solution is the amount of heat energy absorbed (endothermic, positive) or released (exothermic, negative) when a specific amount of solute dissolves in a solvent.
SubstanceSubstance Heat of Solution Heat of Solution
(kJ/mol)(kJ/mol)NaOHNaOH -44.51-44.51
NHNH44NONO33 +25.69+25.69
KNOKNO33 +34.89+34.89
HClHCl -74.84-74.84
Chapter 12Chapter 12
SolutionsSolutions
12.3 Concentration of Solution
Molarity (M)Molarity (M)The concentration of a solution measured in moles of solute per liter of solution.
mol = M L
Pronounced “molar”
Molality (m)Molality (m)
The concentration of a solution in moles of solute per kilogram of solvent.
Since the most common solvent, water, has a density of 1 kg/L, one kilogram of water is the same as one liter of water!
mol = mmkg
DilutionsDilutions• If a solution of known concentration and volume has If a solution of known concentration and volume has
been diluted, we can calculate the new concentration:been diluted, we can calculate the new concentration:
MM11VV11 = M = M22VV22
Example:Example:
20.00 mL of a 0.500 M KBr solution is diluted to 100.00 mL. 20.00 mL of a 0.500 M KBr solution is diluted to 100.00 mL. What is the new molarity?What is the new molarity?
(20.00mL)(0.500M) = (100.00mL)(M(20.00mL)(0.500M) = (100.00mL)(M22))
MM22 =0.100 M =0.100 M
Additional practice problems located in Appendix D p. 902Additional practice problems located in Appendix D p. 902
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