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Chapter 13
Solutions

13-00-01a
Title
Cameroon: location of Lake Nyos
Caption
Lake Nyos in Cameroon was the site of a natural disaster, in which a concentrated solution of carbon dioxide in water suddenly released enough carbon dioxide gas to suffocate 1700 people.
Notes
The carbon dioxide concentration was high due to the high pressure deep in the lake: High pressure increases the solubility of carbon dioxide in water.
Keywords
solution, carbon dioxide, gas, Nyos, Cameroon
13-01
Title
Solvent–solute and solute–solute interactions for NaCl and water
Caption
When NaCl is put into water, the attraction between water molecules and Na+ and Cl- ions (solvent–solute attraction) overcomes the attraction between Na+ and Cl- (solute–solute attraction).
Notes
The negative end of water's dipole will attract the sodium ion; the positive end of water's dipole will attract the chloride ion.
Keywords
solution, dipole, solvent, solute, sodium, chlorine, water
13-02
Title
Composite of NaCl crystal lattice next to beaker of dissolving ions
Caption
In an NaCl solution, the Na+ ions and the Cl- ions are dispersed in the water.
Notes
Water's dipoles are able to overcome the attraction of the ions for one another in the crystal lattice.
Keywords
solution, dipole, solvent, solute, sodium, chlorine, water
13-02-01c
Title
A supersaturated solution
Caption
A supersaturated solution is holding more than the maximum amount of solute. In some cases, such as the sodium acetate solution pictured here, a supersaturated solution may be temporarily stable. Any disturbance however, such as dropping in a small piece of solid sodium acetate (a) will cause the solid to come out of solution (b) and (c).
Notes
Students might think of the disturbance as a "reminder" to the sodium acetate ions that they would be at lower energy if they were organized in a crystal lattice.
Keywords
supersaturated, solution, solid, solute, sodium acetate
13-03
Title
Electrolyte and nonelectrolyte solutions
Caption
Electrolyte solutions contain dissolved ions (charged particles) and therefore conduct electricity. Nonelectrolyte solutions contain dissolved molecules (neutral particles) and do not conduct electricity.
Notes
The negative end of water's dipole will attract the sodium ion; the positive end of water's dipole will attract the chloride ion. The sugar molecule contains many polar O-H bonds; these interact with water strongly enough for the sugar to dissolve.
Keywords
solution, solid, solute, electrolyte, nonelectrolyte, ion, molecule, electricity
13-04
Title
The solubility of several ionic solids as a function of temperature
Caption
In general, solubility increases with temperature, but the relationship is complex.
Notes
The temperature dependence of solubility is often used to purify crystalline solids. The process is called recrystallization.
Keywords
solution, solid, solute, ion, solubility, temperature
13-05
Title
Pressure and solubility
Caption
The higher the pressure above a liquid, the more soluble the gas is in the liquid.
Notes
This explains why soda fizzes after the cap is removed.
Keywords
solution, solid, solute, solubility, pressure
13-06
Title
Two soda cans, one with top popped
Caption
A can of soda pop is pressurized with carbon dioxide. When the can is opened the pressure is released, lowering the solubility of carbon dioxide in the solution and causing it to come out of solution as bubbles.
Notes
The higher the pressure above a liquid, the more soluble the gas is in the liquid. This explains why soda fizzes after the can is opened. The pressure of the open atmosphere is lower than the pressure inside the sealed can.
Keywords
solution, solid, solute, solubility, pressure
13-06-03un
Title
Multistep solution map for liters of a solution to grams of carbon dioxide
Caption
The stated factors use a metric conversion, the measured density of the solution, and the measured solubility of the solute in water to make the conversion.
Notes
The factors can be adapted to any similar liters-grams conversion. The density and solubility factors are determined by experiment, and can be found in reference tables.
Keywords
solubility, solute, density, solution, liter, carbon dioxide
13-06-04un
Title
Multistep solution map for a calculation using percent mass
Caption
The stated factors use the measured density of the solution and the measured solubility of the solute in water (a percent mass) to make the conversion.
Notes
The factors can be adapted to any similar grams-mL conversion. The density and solubility factors are determined by experiment, and can be found in reference tables.
Keywords
solubility, solute, density, solution, sucrose
13-07
Title
How to prepare a 1 molar NaCl solution
Caption
To make 1.0 liter of a 1.0 M NaCl solution, you add 1.0 mole (58.44 g) of sodium chloride to a flask and then dilute to 1.0 liter of total volume. What would happen if you added one liter of water to one mole of sodium chloride? Would the resulting solution be one molar?
Notes
The pear-shaped flask is called a volumetric flask. The mark on the flask was placed there at the factory, providing a precise volume reading.
Keywords
solubility, solute, solution, sodium chloride, volumetric flask, water
13-07-03un
Title
Multistep solution map for converting liters of a solution to grams of a solute
Caption
The stated factors use given molarity data for the solution, and the molar mass of sucrose, as calculated from the periodic table according to the chemical formula.
Notes
The factors can be adapted to any similar liters-mass conversion. The mass-to-moles factor can be found or calculated from periodic table data, and molarity is given in the problem statement.
Keywords
mole, chemical formula, periodic table, mass, solute, molarity, solution, sucrose
13-07-04un
Title
Solution map for determining the volume of a solution containing a known amount of solute
Caption
The factor is the molarity of the solution, and is given in the problem statement.
Notes
Molarity makes a good factor because it has units in both the numerator and denominator.
Keywords
solute, molarity, solution, sodium hydroxide
13-08
Title
Making a solution by dilution of a more concentrated solution
Caption
In this example, we see how to make 5.00 L of a 1.50 M KCl solution from a 12.0 M stock solution. The dilution equation, M1V1 = M2V2 guides us as we determine how much of the stock solution to use.
Notes
The pear-shaped flask is called a volumetric flask. The mark on the flask was placed there at the factory, providing a precise volume reading.
Keywords
solution, solute, molarity, volumetric flask, dilution, concentrated, stock solution
13-08-01un
Title
Multistep solution map for finding the volume of one solution to react with another
Caption
In this example, sulfuric acid is reacted with sodium hydroxide, according to the balanced equation, H2SO4 + 2 NaOH --> Na2SO4 + 2 H2O The stated factors use the given molarity data for sulfuric acid and sodium hydroxide solution, along with a mole-mole factor from the balanced reaction equation to make the conversion. The 2:1 factor arises from the balanced equation.
Notes
The factors can be adapted to any similar solution stoichiometry problem. The molarities must be provided by the problem statement, and the balanced equation provides the mole-mole factor.
Keywords
mole, balanced equation, solution, solute, molarity, stoichiometry
13-08-02un
Title
Multistep solution map for finding the volume of one solution to react with another
Caption
In this example, KI is reacted with Pb(NO3)2, according to the balanced equation, 2 KI + Pb(NO3)2 --> PbI2 + 2 KNO3 The stated factors use the given molarity data for KI and Pb(NO3)2 solutions, along with a mole-mole factor from the balanced reaction equation to make the conversion. The 2:1 factor arises from the balanced equation.
Notes
The factors can be adapted to any similar solution stoichiometry problem. The molarities must be provided by the problem statement, and the balanced equation provides the mole-mole factor.
Keywords
mole, balanced equation, solution, solute, molarity, stoichiometry
13-08-06un
Title
Central relationship in solution stoichiometry problems
Caption
By relating moles of one reactant to moles of another, through a balanced equation, we can solve solution stoichiometry problems.
Notes
The molarity relates moles to volume, allowing the moles-moles problem to connect more closely with the properties that we can measure in the lab—properties such as volume.
Keywords
mole, balanced equation, solution, solute, molarity, stoichiometry
13-08-07un
Title
General approach to solution stoichiometry problems
Caption
Molarity works as a factor to convert measurable volumes of a solution to the equivalent number of moles. By relating moles of one reactant to moles of another, through a balanced equation, we can solve solution stoichiometry problems.
Notes
The molarity relates moles to volume, allowing the moles-moles problem to connect more closely with the properties that we can measure in the lab—properties such as volume.
Keywords
mole, balanced equation, solution, solute, molarity, stoichiometry
13-09
Title
Physiological effects of osmosis
Caption
Drinking seawater promotes dehydration because seawater is a thirsty solution. As the seawater flows through the stomach and intestine it draws water out of bodily tissues.
Notes
Solutes in solutions will always flow from a region of higher concentration to a region of lower concentration. Seawater has a lower concentration of water than pure water has (because of the salt!), so water molecules will migrate toward a sample of seawater. If the seawater is in a person's stomach or intestines, water will move toward the seawater from the body's tissues, resulting in dehydration.
Keywords
osmosis, semipermeable membrane, intestine, dehydration, solution, concentration
13-10
Title
Water molecules migrate through a semipermeable membrane
Caption
Osmosis cell. In an osmosis cell, water flows towards the more concentrated solution.
Notes
Students could be challenged to test this idea out by soaking a carrot in saltwater for a few days. Will the carrot gain or lose water mass?
Keywords
osmosis, semipermeable membrane, intestine, dehydration, solution, concentration
13-10-02un
Title
Multistep solution map for liters of a solution to grams of KCl
Caption
The stated factors use a metric conversion, the measured density of the solution, and the measured solubility of the solute in water (as a mass percent) to make the conversion.
Notes
The factors can be adapted to any similar liters-grams conversion. The density and solubility factors are determined by experiment, and can be found in reference tables.
Keywords
solubility, solute, density, solution, liter, potassium chloride
13-10-03un
Title
Multistep solution map for finding the volume of one solution to react with another
Caption
In this example, hydrochloric acid is reacted with sodium hydroxide, according to the balanced equation, HCl + NaOH --> NaCl + H2O The stated factors use the given molarity data for hydrochloric acid and sodium hydroxide solution, along with a mole-mole factor from the balanced reaction equation to make the conversion. The 1:1 factor arises from the balanced equation.
Notes
The factors can be adapted to any similar solution stoichiometry problem. The molarities must be provided by the problem statement, and the balanced equation provides the mole-mole factor.
Keywords
mole, balanced equation, solution, solute, molarity, stoichiometry
13-10-04m
Title
Osmosis cell #1
Caption
In an osmosis cell, water flows towards the more concentrated solution. Which way will water flow in this example?
Notes
In this example, the left side contains no solute. Water will flow from left to right.
Keywords
osmosis, semipermeable membrane, intestine, dehydration, solution, concentration
13-10-05n
Title
Osmosis cell #2
Caption
In an osmosis cell, water flows towards the more concentrated solution. Which way will water flow in this example?
Notes
In this example, the left side contains more solute than the left. Water will flow from right to left.
Keywords
osmosis, semipermeable membrane, intestine, dehydration, solution, concentration
13-10-06o
Title
Osmosis cell #3
Caption
In an osmosis cell, water flows towards the more concentrated solution. Which way will water flow in this example?
Notes
In this example, the solute concentrations are the same; there will be equal flow both ways.
Keywords
osmosis, semipermeable membrane, intestine, dehydration, solution, concentration
13-10-07p
Title
Sodium chloride solution showing sodium chloride dissolved as units of NaCl
Caption
What is wrong with this depiction of a solution of NaCl in water?
Notes
NaCl is a strong electrolyte; it should ionize, but the picture fails to show this.
Keywords
ion, solution, solute, electrolyte, solubility, sodium chloride, water
13-10-10un
Title
Multistep solution map for liters of a solution to grams of KCl
Caption
The stated factors use a metric conversion, the measured density of the solution, and the measured solubility of the solute in water to make the conversion.
Notes
The factors can be adapted to any similar liters-grams conversion. The density and solubility factors are determined by experiment, and can be found in reference tables.
Keywords
solubility, solute, density, solution, liter, potassium chloride

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