Solutions

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Chapter 15

• Solutions

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• MATTER
• Mixtures Pure Substances
• Homogeneous Elements
• Heterogeneous Compounds

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Solutions

• Terminology
• Solute
• Solvent
• Soluble
• Insoluble -

the substance that gets dissolved
the substance that does the dissolving
able to be dissolved
cant be dissolved
Miscible/Immiscible
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Why does something dissolve/not dissolve?

• Rule of Thumb
• Nonpolar Substances
• Polar Substances

like dissolves like
i.e. polar solvents dissolve polar solutes
nonpolar nonpolar
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Polar vs. Nonpolar
polar
Water is __________
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polar/nonpolar?
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Polar vs. Nonpolar
polar
Sucrose is __________
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Polar vs. Nonpolar
polar
Sucrose is __________
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Polar vs. Nonpolar
polar
Sucrose is __________
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Salt is __________
polar
In fact, All ionic compounds are ________
polar
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Methanol and other alcohols are __________
polar
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Hydro-carbons are ______
nonpolar
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Hydro-carbons are ______
nonpolar
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Why does something dissolve/not dissolve?

• Rule of Thumb
• Nonpolar Substances
• Polar Substances

like dissolves like
i.e. polar solvents dissolve polar solutes
nonpolar nonpolar
Hydrocarbons oils, fats, grease etc.
Ionic compounds
Water, sugar, alcohol (anything w/ -OH groups)
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Solvation

• The solvent particles pull the solute particles
  apart and surround them.

Solvation Video
Solvation - Ionic simulation.jnlp
Solvation - molecular.notebook
Solvation occurs when the attractive forces
between the solvent and solute particles is
________ than the attractive forces holding the
solute particles together.
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Dissolving Equations - Revisited

• Write the dissolving equation for each
• Sodium chloride
• NaCl(s) ? Na(aq) Cl-(aq)
• Silver sulfide
• Ag2S(s) ? 2 Ag(aq) S2-(aq)
• Sucrose (C12H22O11)
• C12H22O11 (s) ? C12H22O11 (aq)

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3 Factors affecting rate of solvation

• Temperature
• Increases movement of particles -gt mixes faster
• Agitation
• Allows particles to come into contact at a faster
  rate -gt mixes faster
• Surface Area
• Increases the contact area, thus allows
  particles to come into contact faster -gt mixes
  faster

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Heats of Solution

• Energy Absorbed
• Energy Released

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Solubility

• the maximum concentration of solute that will
  dissolve in a given amt. solvent (_at_ given temp.,
  pressure)
• Saturated
• Unsaturated -

Contains the maximum amount of solute
Contains less than the maximum amount of solute
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Solubility

• the maximum amount of solute that will dissolve
  in a given amt. solvent (_at_ given temp.,
  pressure)

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Factors Affecting Solubility
1) Nature of solute solvent
like dissolves like
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Factors Affecting Solubility
2) Temperature

• NaCl(s) ? Na (aq) Cl-(aq)

Increasing temperature favors the endothermic
process
Most solids dissolve ____________ solubility
______ as temp ?
Figure 11.6 Zumdahl Chemistry 7th Edition
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Temperature Solubility

• CO2 (g) ? CO2 (aq)

All gases dissolve ____________ solubility ______
as temp ?
Figure 11.7 Zumdahl Chemistry 7th Edition
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Factors Affecting Solubility
Supersaturated -
A solution that contains more than the maximum
concentration of solute
http//genchem.chem.wisc.edu/demonstrations/gen_ch
em_pages/11solutionspage/crystallization_from_supe
r.htm link to supersaturated demo
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Factors Affecting Solubility
3) Pressure Henrys Law
At a given temp, the solubility (S) of a gas is
directly proportional to the pressure (P) of the
gas above the liquid.
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Factors Affecting Solubility
Henrys Law
Ex. If the solubility of a gas is 0.66 g/L at
10.0 atm, what is the pressure on a 1.0-L sample
that contains 1.5 g gas?
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How would the solubility be affected by
increasing temp. for following

• Heat NaCl (s) ? Na (aq) Cl- (aq)
• Ce2(SO4)3 (s) ? 2 Ce3 (aq) 3 SO42-(aq)
  heat
• H2S (g) ? H2S (aq)

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How would the solubility be affected by
increasing pressure for following

• Heat NaCl (s) ? Na (aq) Cl- (aq)
• Ce2(SO4)3 (s) ? 2 Ce3 (aq) 3 SO42-(aq)
  heat
• H2S (g) ? H2S (aq)

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How would the solubility be affected by agitating
mixtures of each of the following

• Heat NaCl (s) ? Na (aq) Cl- (aq)
• Ce2(SO4)3 (s) ? 2 Ce3 (aq) 3 SO42-(aq)
  heat
• H2S (g) ? H2S (aq)

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Expressing Concentration
Concentration - how much solute is dissolved in a
given amount of solvent or solution possibilities
Molarity (M)
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Expressing Concentration
1) 24.5 g NaCl is dissolved in a total volume of
2.0 L. What is the concentration (molarity) of
the NaCl solution?
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Expressing Concentration

• 2) You have 5.0 L of a 2.5 M soln of NaOH.
• How many moles of NaOH are present?
• How many grams of NaOH are present?

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Expressing Concentration
3) You need 27.3 g of NaCl. All you have is a
0.15 M solution of NaCl. How many milliliters of
solution will you need?
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Expressing Concentration
4) How could you prepare 250. mL of a 0.10 M
solution of copper (II) nitrate, Cu(NO3)2?
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Dilution Problems
When diluting a concentrated solution, the key
to solving for the new concentration is that the
number of moles of solute (n) does not change.
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Dilution Problems
1) How many milliliters of 1.00 M Cu(NO3)2
solution are needed to prepare 250. mL of a 0.100
M solution of Cu(NO3)2.
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Dilution Problems
1) How many milliliters of 12.0 M HCl solution
are needed to prepare 10.0 L of a 0.500 M
solution of HCl?
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Dilution Problems
2) How many milliliters of an 18.0 M H2SO4
solution are needed to prepare 3.0 L of a 0.200 M
solution?
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Dilution Problems
3) How many milliliters of 1.50 M HCl must be
added to appropriate amount of H2O to make 25 mL
of 0.500 M HCl?
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Dilution Problems
4) What is the concentration of a solution made
by diluting 50.0 mL of a 3.00 M solution of HCl
to 500. mL?
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Predicting PrecipitatesRevisited
Write the total and net ionic equation for when
the following solutions are mixed. 1) potassium
chromate lead (II) nitrate
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Predicting PrecipitatesRevisited
Write the total and net ionic equation for when
the following solutions are mixed. 2) silver
nitrate iron (III) chloride
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Molarity 3-step Mole Method
CuCl2 (aq) 2 AgNO3 (aq) ? 2 AgCl (s)
Cu(NO3)2 (aq)
2) 125 mL of a silver nitrate solution reacts
with enough copper (II) chloride to produce 0.300
g of AgCl. What is the molarity of the initial
silver nitrate solution?
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Molarity 3-step Mole Method
CuCl2 (aq) 2 AgNO3 (aq) ? 2 AgCl ( )
Cu(NO3)2 ( )
1) How many milliliters of 0.15 M copper (II)
chloride are needed to react with silver nitrate
to produce 50.0 g of solid silver chloride?
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Ch. 15 Test Overview

• 14 mult. Choice (2pt.)
• 8 pt. free response
• 36 total points