Name
Regents Chemistry
Valley Stream South High School

What you need to know and be able to do by the end of this unit?
• State the factors that affect the solubility of a substance.
• Use the solubility curve (table G) to, determine the saturation point of a substance.
• Use the solubility curve (table G) to describe a solution, in terms of its degree of saturation.
• Determine the concentration of a solution
• Explain the affect of the addition of a nonvolatile solute on the boiling and freezing points of a solution.
Key Subject Competencies
• Define a solution.
o Identify the parts of a solution, o Determine the factors that affect the solubility of a solution.
o Distinguish between saturated, unsaturated, and supersaturated solutions.
• Use Table G to determine if a solution is saturated, unsaturated, and supersaturated.
o Predict the solubility of an ionic compound by using the solubility table, o Describe a solution in terms of saturated, supersaturated, or unsaturated.
o Identify the gases on Table G and explain the effects of temperature on their solubility, o Explain what is meant by "like dissolves like."
• Use Concentration formula (Table T) to determine moles or Molarity.
o Determine percent by mass of a substance, o Determine percent by volume of a substance, o Calculate concentration in pprn.
• Define the term nonvolatile solute.
o Explain why the presence of a nonvolatile solute increases the boiling point of a solution, o Explain why the presence of a nonvolatile solute decreases the freezing point of a solution, o Understand that the greater the concentration of solute particles, the greater the effect on the boiling and freezing points of a solution.
• Define the term electrolyte.
o Give examples of substances that are electrolytes.
o Explain that a solution's ability to conduct electricity depends on the concentration of ions in the particles.
Vocabulary - * Denotes those terms most frequently appearing on Regents Examinations.
*Boiling point Percent by mass ^Solution
*Molarity ^Saturated ^Supersaturated
Parts per million (ppm) Solute *Unsaturated
*Vapor pressure *Solvent

1. Solution:
2. Solute:
3. Solvent;
4. Solubility:
5. Factors affecting rate/amount of solubility:
RATE AMOUNT a.
b.
6, Types of solutions: a. Saturated: b. Unsaturated: c. Supersaturated:
7. Dilute solution:
8. Concentrated solution:

1. In an aqueous solution of potassium chloride., the solute is
A) Cl B) K C) KC1 D) BhO
2. In an aqueous solution of sodium fluoride
;
Hie solvent is
A) F B) Na C) NaF D) HzO
3. At room temperature, the solubility of which solute in water would be most affected by a change in pressure?
A) methanol B) sugar
C) carbon dioxide D) sodium nitrate
4. The solubility of a salt in a given volume of water depends primarily on the
A) surface area of the salt crystals
B) temperature of the water
C) rate at which the salt and water are stirred
D) pressure on the surface of the water
5. What Celsius temperature is equal to 142 K?
6. Base your answer to the following question on the information below.
In a laboratory, a student makes a solution by completely dissolving 80.0 grams of
KN03(s) in 100.0 grams of hot water. The resulting solution has a temperature of 60. °C.
The room temperature in the laboratory is 22°C.
Describe a laboratory procedure that can be used to recover the solid solute from the aqueous solution.

': Form LsS.lA
SOLUTIONS
Name
Date Period
To explain why substances dissolve
Definition: Solution = homogeneous mixture
ik Nature of mixtures
•w" consists of two or more kinds of matter
•&- each substance in a mixture retains its own properties
Tt sugar and water - sweet and wet
-fc brine (salt water) - salty liquid
~& the composition is variable (not constant)
•&• can be separated by physical means
* Distinguishing solutions from mechanical mixtures
•& properties of solutions
~k homogeneous mixtures - composed of two or more substances and have variable composition BUT the particles are distributed evenly throughout each other SO the composition is uniform
~fe the solution appears to be one substance
7k consist of a solute dissolved in a solvent
•& solute - substance that IS dissolved by another
•£- solvent
•& substance that dissolves another
ik continuous phase - salt dissolved in water appears to be a liquid
Solubility - ability to dissolve in water
* Factors that affect solubility
•& Degree of solubility (how much dissolves)
7*r nature of solute and solvent
fa in order for a solvent to dissolve a solute, it must exert forces of attraction on the solute
T*T polar solvents such as water dissolve polar and ionic solutes because they exert mutual attractions that cause their particles to intermingle
iK nonpolar solvents such as benzene do
NOT dissolve polar and ionic substances because they exert no forces of attraction that would cause the particles to separate so they can intermingle
~k oil and water do NOT mix
fa nonpolar substances such as fat dissolve in nonpolar solvents such as benzene because the forces of attraction are too weak to prevent the particles from freely intermingling
fa like dissolves like (See Table F - Table of
Solubilities in Water)
?V Temperature (See Table G - Solubility Curves)
fa solubility of solid solutes generally increases as temperature increases
fa solubility of gaseous solutes generally decreases as temperature increases
"U
~k Pressure
•fa solids and liquids - no effect
•fa gases: Henry's Law - mass of a dissolved gas in a liquid is directly proportional to the pressure of the gas
Rate of solution
Factor Affect on Solid Solute
Affect on Gaseous
Solute
Particle Size
Stirring
Amount of dissolved solute
Temperature reducing particle size by crushing increases the rate by increasing surface area increases the rate by exposing fresh solvent to solute and increasing kinetic energy as the amount of dissolved solute increases, the rate decreases as the temperature increases, the rate increases not applicable decreases the rate by
Increasing kinetic energy, thereby reducing solubility as the amount of dissolved solute increases, the rate decreases as the temperature increases, the rate decreases
Saturation (see Table G)
•£• Saturated solution - solution that cannot dissolve any more solute at a given temperature
T^T added solute will NOT dissolve
A Unsaturated solution - solution that can dissolve more solute at a given temperature it added solute will dissolve
& Supersaturated solution - solution that holds more solute than it can dissolve at a given temperature
~V produced by dissolving solute at a high temperature and allowing it to cool slowly
•fa addition of solute causes precipitation of the excess
Concentration - the amount of solute compared to solvent
•& Qualitative descriptions
fa concentrated - large amount of solute compared to the amount of solvent
fa example - concentrated orange juice
fa dilute - small amount of solute compared to the amount of solvent
fa example - weak coffee

: Form N8.1A
SOLUTIONS
Page 2
Answer the questions below by circling the number of the correct response
1. A reason why many salts dissociate in water is that water
1, consists of polar molecules, 2. contains ionic bonds, 3, has a linear structure, 4. does not ionize
2. Ammonia gas and hydrogen chloride gas are very soluble in water, which answer best explains the reason for this? 1, water is a good solvent for gases, 2. NHs, HCI, and fyO molecules are polar. 3.
NHs, and HCI molecules are very compact 4. NHs, HCI, and fyQ molecules are electrically symmetrical,
3. The attraction of water molecules to ions of a solute is
1. hydration, 2. dispersion, 3. ionization, 4. crystallization
4. When an ionic solid dissolves in water, which of the following occurs? 1. ionization of molecules 2. hydration of molecules
3. dissociation of ions 4. formation of ionic bonds with water
5. A reason why many ionic salts dissociate in water is that water
1. consists of polar molecules 3. contains ionic bonds
2. has a linear structure 4. does not ionize
6. A solution which contains less solute than should normally dissolve is 1. concentrated, 2. unsaturated, 3. saturated,
4. supersaturated
7. To a solution of NH4d, a crystal of NH4CI is added. The crystal
• falls to the bottom and more solid comes out of the solution. This indicates the original solution was 1. unsaturated,
2, supersaturated, 3. saturated, 4. concentrated
8. A solution in which no more solute can still be added and dissolve is
1. supersaturated 3. unsaturated
2. saturated 4. concentrated
9. To a solution of NaCI, a crystal of NaCI is added and the crystal dissolves. The solution must have been 1. supersaturated,
2. saturated, 3, concentrated, 4. unsaturated
10. A solution which contains a maximum amount of solute that can be dissolved under the existing conditions is 1. saturated,
2. unsaturated, 3. dilute, 4. supersaturated
11. Crystals of NaCI, when added to a solution of this salt that is in equilibrium with excess sodium chloride, will 1. dissolve in the solution, 2. cause additional sodium chloride crystals to separate from the solution, 3. form a supersaturated solution, 4. cause no change in the concentration of the solution
12. A saturated solution of which salt would be the most concentrated at 30°C? (see solubility chart) 1 . NaCI, 2. NaCI0
3
, 3. KCI,
4. KCI0
3
13. Which saturated solution would be most dilute at 0°C?
1. Kl 3.
2. NaNOs 4.
14. Which compound is most soluble in water?(see solubility chart)
1. silver acetate 3. lead nitrate
2, silver chloride 4. silver sulfate
1 5. As the temperature increases from 30°C to 40°C, the solubility of potassium nitrate in 100 g of water increases by approximately (see solubility chart)
1. 5 grams 3. 15 grams
2rlO grams 4. 20 grams
1 6, Which compound is least soluble in 1 00 grams of water at
1QOC?(see solubility chart)
1. KN03 3. NaCI
2. Kl 4. KC|0
3
17. A small cr/stal of the slightly soluble salt calcium sulfate dissolves in a solution of calcium sulfate. The original solution must have been 1. dilute and saturated, 2. concentrated and saturated,
3. dilute and unsaturated, 4. concentrated and unsaturated
18. As the temperature increases and the pressure remains constant, the solubility of a gas in a solution 1. decreases, 2. remains the same, 3, increases, 4. varies directly
19. As the pressure on a gas increases, temperature remaining constant its solubility in water 1. decreases, 2. remains the same,
3, increases, 4. varies inversely
20. Which silver compound is most soluble in water? (see solubility chart) 1. AgCl, 2. Agl, 3. AgaSO^ 4. AgNOs
21 . How many grams of KCI are required to saturate 1 000 grams of
H20 at 80°C?(see solubility chart) 1. 390, 2. 500, 2. 800, 4. 1000
Evan P. Silberstein, 2003

Most of the materials that you use every day are not pure substances. It is more likely that they are mixtures. This topic "will explore an important type of mixture, the solution. The nature and properties of solutions are important concepts used in chemistry. One reason they are so important is that most chemical reactions take place in solutions. In this topic you will study the nature and properties of solutions and ways to express the concentration of solutions.
A solution is a homogeneous mixture of substances in the same physical state. Solutions contain atoms, ions, or molecules of one substance spread uniformly throughout a second substance.
When salt (NaCl) is stirred into water, the individual ions of the salt separate and uniformly spread throughout the water, forming a solution.
A solid maybe dissolved in another solid. Brass is a mixture of zinc and copper. When metals are mixed to form a solution., the result is called an alloy. Air is an example of a mixture of gases forming a solution.
Although solutions exist in all three states, the discussion in this topic will be limited to liquid solutions. Perhaps the most common type of solution is one in which a solid or a liquid is dissolved in a liquid.
The terms solute and solvent are commonly used to identify the parts of a solution. la general terms, the soiute is the substance that is being dissolved, and it is the substance present in the smaller amount. When solid sodium nitrate dissolves hi water, the sodium nitrate is the solute.
The substance that dissolves the solute is the
solvent, and it is present in the greater amount.
Water is, perhaps, the most common solvent. Water solutions are called aqueous solutions, and the notation (aq) is used in equations to show that the substance is dissolved in water.
NaCKs) -> Na+fa<?) + Cl~(ag)
Once the salt and water are stirred and the mixture becomes homogeneous, the dissolved particles will not settle. Liquid solutions are clear, and light will pass through a solution without being dispersed, as shown in Figure 7-1 on the next page.
Properties of Solutions 95

charged chloride ions are attracted to the positive polar substances dissolve in polar solvents.
Beam of light
Solution Not a solution
Figure 7-1. Light passing through a solution: The particles in a solution are too small to disperse light.When light passes through a liquid with larger particles, such as gelatin in water, you can seethe beam because larger particles disperse light.
Solutions may or may not have color. For example, solutions of copper salts have a characteristic blue color, while a solution of sodium nitrate is colorless.
7-2, The dissolving process: Ionic and polar solutes dissolve in polar solvents because unlike charges attract each other.
1. Solutions are homogeneous mixtures.
2. Solutions are clear and do not disperse light.
3. Solutions can have color.
4. Solutions will not settle on standing.
5. Solutions will pass through a filter.
You've noticed that some things easily dissolve in water or other solvents. When you make a cup of coffee, certain materials in the coffee grounds dissolve but other materials don't. Sugar will readily dissolve in the cup of coffee but the spoon you use to stir the solution does not dissolve. How much of a solute will dissolve in a certain amount of solvent at a certain temperature is known as solubility.
Materials with a high solubility are said to be soluble: materials with a low solubility are said to be insoluble. "What factors determine the solubility of a solute hi a solvent?
E OF SOLUTE SOLVENT When sodium chloride dissolves in water it does so because its positively and negatively charged ions are attracted to the oppositely charged ends of the polar water molecule. The dissolving process is shown in Figure 7-2. The positively charged sodium, ions are attracted to the negative pole of the water molecules. The attractive forces between the water molecules and sodium ions are greater than the attractive'forces between the sodium and chloride ions, hi like manner, the negatively
96 Topic 7
Nonpolar substances, such as fats, do not dissolve hi water because there aren't strong attractive forces between the fat molecules and the water molecules. Fat molecules will dissolve in nonpolar solvents. The forces that hold the nonpolar molecules to each other are quite weak, and the molecules simply mix together. The term "like dissolves like" is often used to describe what solutes will dissolve in what solvents. Table 7-1 summarizes this concept.
Solute
Type nonpolar
• polar ionic
Nonpolar
Solvent soluble insoluble insoluble
Polar
Solvent insoluble soluble soluble
An interesting and important case of "like dissolves like" is found in the action of soaps. Greases, which are nonpolar., won't easily wash off our hands in water, which is polar. Soaps are long carbon chains that have one end that is polar, allowing the soap to dissolve in water. The other end of the soap is nonpolar, and grease will dissolve in it.
E As temperature increases, most solids become more soluble in water, A few exceptions exist. Gases react in the opposite manner.
As temperature rises, the solubility of all gases in liquids, decreases.

Pressure; Ji^-s little or no..effecton the solubility of solid or liquid solutes. Pressure does affect the solubility of gases in liquids. As pressure increases, the solubility of gases in liquids increases. When a can of soda is opened, the pressure decreases. The carbon dioxide is no longer as soluble at the lowered pressure, and it escapes as bubbles.
11. What happens when NaCI(j) is dissolved in water?
(i)"G~ ions' are attracted YotHe'oxygerTatomTof the water. (2) Cl~ ions are attracted to the hydrogen atoms of the water. (3) Na* ions are attracted^to the hydrogen atoms of the water. (4) No attractions are involved; the crystal just falls apart.
12. Which diagram best illustrates the ion-molecule attractions that occur when the ions of NaQ{5) are added to water?
(D
H-
:o
1. In a true solution, the dissolved particles (1)are visible to the eye (2) will settle out on standing
(3) are always solids (4) cannot be removed by filtration
2. When a teaspoon of sugar is added to water and stirred,the sugar (1) melts (2) dissolves
(3) condenses (4) evaporates
3. In an aqueous solution of potassium chloride, the solute is (l)CI-only (2)K
+ only (3) K+CT (4) H
2
0
4. Which sample of matter is a mixture? (1) H
2
O(s)
(2)H
2
0(€) (3)NaC!(€) (4)NaCI(ag) .
5. Most ionic substances are soluble in water because water molecules are (l)nonpolar (2) inorganic
(3) ionic (4) polar
6. Nonpolar solvents will most easily dissolve solids thatare (1) ionic (2) covalent (3) metallic
(4) colored
7. An aqueous solution of copper sulfate is poured into a filter paper cone.What passes through the filter paper? (1) only the solvent (2) only the solute
(3) both solvent and solute (4) neither the solute nor solvent
8. As the temperature rises, the solubility of all gases in water (1) decreases (2} increases (3) remains the same (4) depends on the gas
9. A decrease in pressure has the greatest effect on a solution that contains (1) a gas in a liquid
(2) a solid in a solid (3) a liquid in a liquid
(4) a solid in a liquid
10. Under which conditions are gases most soluble in water? (1) high temperature and high pressure
(2) high temperature and low pressure (3) low temperature and high pressure (4) low temperature and idw"pressure
(2)
(4)
0.
Solubility information may be presented in different ways. Table G of Reference Tables for Physical
Setting!Chemistry presents quantitative information showing the relationship of grams of solute that may be dissolved at various temperatures.
Table F provides some general guidelines about the solubility of ionic substances. You will need to be able to interpret information from both tables.
Table G shows the number of grams of a substance that can be dissolved in
100. g of water at temperatures between 0°C and
100°C. Each line represents the maximum amount of that substance that can be dissolved at a given temperature. All of the lines that show an increase in solubility as temperatures increase represent solids being dissolved in water. Although these lines on the graph, show an increase in solubility as temperature increases, a few solids, such as cesium sulfate, become less soluble as temperature increases.
Three lines show decreasing solubility with increasing temperature. These three lines represent the gases NHg, HC1, and S0
2
. The solubility of all gases decreases with increasing temperature.
Properties of SoSutions 97

Table G - Solubility Curves
Take a look at Table G in your Reference Tables and also up at the projections on the board. Together we wfll determine the following:
1. What is the solubility of KI at 20 degrees Celsius per lOOg of water?
a.
2. What is the solubility of KNOs at 50 degrees Celsius per lOOg of water?
a.
3. What is the solubility of SC>2 at 10 degrees and 90 degrees Celsius per lOOg of water?
• b.
4. What is the solubility of KHs at 10 degrees and 90 degrees Celsius per lOOg of water?
a, b.
Trends in Table G
1. Temperature versus solubility of a solid
2. Temperature versus solubility of a gas
10

SOLUTIONS
Form WS8 . 1 . 2A Name
Date Period
The solubility of solid solutes generally increases as temperature increases, while the solubility of gaseous solutes generally decreases as temperature increases. A solution that holds as much solute as can dissolve at a given temperature is saturated. A solution that can dissolve more solute at a given temperature is unsaturated. A solution that holds more solute than can dissolve at a given temperature is supersaturated. The amount of solute that is needed to form a saturated solution at various temperatures can be graphed. This is what is shown in Table G. The values in Table G are based on solute dissolved in 100 g of water.
Since water has a density of 1 g/mL, the graph can be considered to be based on
100 mL of water. A 200 mL sample of water would be able to dissolve twice as much at each temperature.
Answer the questions below by referring to Table G.
1-10
Table G SokftlEtty Curves
1. The compound which is the most soluble at 20°C is
2. The compound which is the least soluble at 10°C is.
3. The compound which is the least soluble at 80°C is.
4. The number of grams of potassium nitrate needed to saturate 100 mL of water
0 1& 20 30 40 50 SO 70 80 90 100
Temperature ("C) at 70°C is .
5. The formulas of the compounds which vary inversely with the temperature are and
6. One hundred mL of a sodium nitrate solution is saturated at 10°C. How many additional grams are needed to saturate the solution at 50°C?
7. One hundred mL of a saturate KC1 solution at 80°C will precipitate 10 grams of salt when cooled to what temperature?
8. The two salts that have the same degree of solubility at 70°C are and
9. The salt with a solubility is least affected by a change in temperature is
10. The salt that has the greatest increase insolubility in the temperature range between 30°C and 50°C is
11. The number of grams of sodium nitrate that must be added to 50jnL,of water to produce a saturated solution at 50°C is
12. A saturated solution of potassium chlorate is made at 10°C by dissolving the correct mass of salt in 100 mL of water.
When the solution is heated to 90°C, how many grams must be added to saturate the solution?
Continue
11

1
: Form ws 8 . l. 2A Solubility Curves
SOLUTIONS ' Page 2
13. At what temperature do saturated solutions of sodium chloride and potassium chloride contain the same mass of solute per 100 rnL of water?
14. A saturated solution of potassium nitrate is prepared at 60°C using 200 mL of water. If the solution is cooled to 30°C, how many grams will precipitate out of the solution?
15. How many more grams of ammonia can be dissolved in 100 mL of water at 10°C than at 90°C?
16. A saturated solution of sodium nitrate in 100 mL of water at 40°C Is heated to 50°C. The rate of increase in solubility grams per degree is .
17. Thirty grams of KC1 is dissolved in 100 mL of water at 45°C. The number of additional grams of KC1 that would be needed to make the solution saturated at 80°C is .
Evan P. Silberstein, 2003
12

Name CONCEPT REVIEW- Solutions
A. What factors determine the amount of solute that will dissolve in a solvent?
B.
What factors determine the rate at which a solute dissolves in a solvent?
WHAT IS A SOLUTION?
In the space provided, write the letter of the description that best matches the term or phrase
1. Solution A. in a solution, the substance in which the solid is dissolved
2. Solvent B. describes a solution in which the solvent is water
3. Solute C. in a solution, the substance dissolved in the solvent
4._ __ Aqueous D. a stable homogenous mixture
What is the solubility of each of the following substances at the temperatures given?
6. KIat20°C
7. HC1 at 50°C
8. NH
3 at90°C
9. NH
4
C1 at 85°C
10.NaClatlOO°C
Are the following saturated, unsaturated, or supersaturated?
11. 100gofNaN0
3 at20°C
12. 110eofKIat4040°C
13.30gofKClO
3 at60°C
14. 10gofNH
3 at90°C _
15. 55gofNH
3
10°C
0 10 20 30 40 50 ©0 70 SO 90 100
Temperature (
S
C)
13

Answer the following questions based on the solubility curve below.
1. Which salt is least soluble in water at 20° C?
2. How many grams of potassium chloride can be dissolved in 200 g of water at 80° C?
150
3. At 40° C, how much potassium nitrate can be dissolved in 300 g of
• water? •
4. Which salt shows the least change in solubility from 0° - 100° C?
5, At 30° C, 90 g of sodium nitrate is dissolved in 100 g of water. Is this solution saturated, unsaturated or supersaturated?
20 30 40 50 60 70 80 90 100
6. A saturated solution of potassium chlorate is formed from one hundred grams of
'water. If the saturated solution is cooled from 80° C to 50° C, how many grams of precipitate are formed? ._
7. What compound shows a decrease in solubility from 0°- to 100° C?
8. Which salt is most soluble at 10° C? •
9. Which salt is least soluble at 50° C? '
I 10. Which salt .is least soluble at 90° C?
14

Name
Worksheet A — Solubility Curves
Solubility Curves- Use Table G to answer the following questions.
1. At what temperature would KNOs and NaNOs have the same solubility?
2. At 40° s
how many grams of NaNOs dissolve?
3. What salt will change its solubility the least with an increase in temperature?
4. How is the solubility of a gas affected as temperature increases?
5. How much HC1 will dissolve in Water at the a. boiling point of water b. freezing point of water^
6. What type of NaNOs solution is present at 30° and 90g of solute?
7. What type of Nt^Cl solution is present at 70°C and 80g of solute?
8. What salt is least soluble at 0°C?
9. How much solute can HC1 and NH
3
dissolve at 5°C?
10. What salt increases its solubility the most with an increase in temperature?
15

Name
Worksheet B
Solutions
1-6 Refer to Reference Table G
1. Which of the salts shown of the graph is the least soluble in water at 10°C?
2. Which of the salts shown on the graph has the greatest increase in solubility as the temperature increases from 30 to 60°?
3. Which of the salts has its solubility affected the least by a change in temperature?
4. Thirty grams of KC1 are dissolved in lOOg of water at 45°C. Howmany additional grams of KC1 are needed 10 make the solution saturated at 80°C?
5. At 20°C a saturated solution of sodium chlorate contains 100 grams of solute in lOOg of water. How many grams of sodium chlorate must be added to saturate the solution at 5O°C?
6. Identify the following solutions as saturated, unsaturated, or supersaturated.
a. 40g of KC1 in lOOg of H
2
0 at SO°C b. 120g of KN0
3
in lOOg of H
2
0 at 60°C __^__ c. 80g of NaN0
3
in lOOg of H
2
0 at 10°C __^____ I
7. Soda is produced by dissolving carbon dioxide in water, CC>2(aq).
a. When the cap is removed from a soda bottle, CC>2(g) is releases from solution.
State the relationship between gas solubility and pressure b. When the soda is allowed to warm to room temperature, more CC>2(g) is released.
State the relationship between gas solubility and temperature c. On the graph axis, sketch a curve for gas solubility and temperature: Label axes.
16

Pressure has little or no effect on the solubility of solid or liquid solutes. Pressure does affect the solubility of gases in liquids. As pressure increases, the solubility of gases in liquids increases. When a can of soda is opened, the pressure decreases. The carbon dioxide is no longer as soluble at the lowered pressure, and it escapes as bubbles.
11. What happens when NaCI(s) is dissolved in water?
(1) Cl~ ions are attracted to tHe'oxygen atoms "of the water. (2) Cl~ ions are attracted to the hydrogen atoms of the water. (3) Na
+
ions are attracted to the hydrogen atoms of the water. (4) No attractions are involved; the crystal just falls apart.
12. Which diagram best illustrates the ion-rnolecule attractions that occur when the ions of NaCl(s) are added to water?
H
:o
1. In a true solution, the dissolved particles (1)are visible to the eye (2) will settle out on standing
(3) are always solids (4) cannot be removed by filtration
2. When a teaspoon of sugar is added to water and stirred,the sugar (1) melts (2) dissolves
(3) condenses (4) evaporates
3. In an aqueous solution of potassium chloride, the solute is (DCTonly (2)K+only (3) K*cr (4) H
2
0
4. Which sample of matter is a mixture? (1) H
2
O(5)
(3)NaCl(€) (4)
5. Most ionic substances are soluble in water because water molecules are (l)nonpolar (2) inorganic
(3) ionic (4) polar
6. Nonpolar solvents will most easily dissolve solids thatare (1) ionic (2)covalent (3) metallic
(4) colored
7. An aqueous solution of copper sulfate is poured into a filter paper cone. What passes through the filter paper? (1) only the solvent (2) only the solute
(3) both solvent and solute (4) neither the solute nor solvent
8. As the temperature rises, the solubility of all gases in water (1) decreases (2) increases (3) remains the same (4) depends on the gas
9. A decrease in pressure has the greatest effect on a solution that contains (1 ) a gas in a liquid
(2) a solid in a solid (3) a liquid in a liquid
(4) a solid in a liquid
1 0. Under which conditions are gases most soluble in water? (1) high temperature and high pressure
(2) high temperature and low pressure (3) low temperature and high pressure (4) low temperature and iow'pressure
(2)
[3)
(4) o:
Solubility information may be presented in different ways. Table G of Reference Tables for Physical
Setting/Chemistry presents quantitative information showing the relationship of grams of solute that may be dissolved at various temperatures.
Table F provides some general guidelines about the solubility of ionic substances. You will need to be able to interpret information from both tables.
Table G shows the number of grams of a substance that can be dissolved in
100. g of water at temperatures between 0°C and
100°C. Each line represents the maximum amount of that substance that can be dissolved at a given temperature. All of the lines that show an increase in solubility as temperatures increase represent solids being dissolved in water. Although these lines on the graph show an increase in solubility as temperature increases, a few solids, such as cesium sulfate, become less soluble as temperature increases.
Three lines show decreasing solubility with increasing temperature. These three lines represent the gases NHg, HC1, and SO
2
. The solubility of all gases decreases with increasing temperature.
Properties of Solutions 97

120 no
T O O g 90
1 30
01
S 70
QJ
3 60
"5
£)
50
1* 40
ID
•I 30
<J~I
20
/
D,
/ c y /
/ y /
/
/
/
/
/
•A
10
10 20 30 40 50 60 70 80 90 TOO
Temperature (°C)
Figure 7-3. A solubility curve
Figure 7-3 shows four positions relative to a line of maximum solubility. Position A is below the maximum line of solubility. At this position, the temperature is 35°C, and 25 g of solute X dissolve.
Because at this point the solution holds less solute than the maximum it can hold,, the solution is said to be unsaturated. If there is not a temperature change, an additional 30 g can be added to bring X to position B.
Position B is on the line of maximum solubility.
A solution that contains a maximum amount of solute that will dissolve at a specific temperature is saturated. At this position, the solution contains
55 g of X. The addition of more solid solute will not result in more being dissolved. Any additional solid that is added will simply settle to the bottom of the container.
If the temperature is reduced to 20°C, only 35 g of X can dissolve. When the temperature of the solution at B is reduced, the most likely event is that the excess 20 g of X will precipitate, and thesolution will remain saturated at point C. On rather rare occasions, as the temperature decreases, crystals do not form and the substance may be at position D.
At position D
;
there is more solid dissolved than normal. A solution that holds more solute than is present in a saturated solution at that temperature is supersaturated. These solutions are quite .unstable. The addition of a single solid crystal of the~substance will cause additional solid to form, and the solution will return to a saturated ' condition. If no temperature change occurred, the solution would become saturated at point C
;
with
" 20 g of the substance precipitating. The only way to make a supersaturated solution is to cool a saturated solution in which there are no crystals or impurities, such as dust, present.
_ t—*•* t 1
'*. 'There are two~terrns
T that ate somewhat useful in f
**' describing toncenti ations of solutions Dilute solu- •>*
? tJons'coritairvrelatively small a mo ants'of dissolved
. * solute m a large amount of solvent For example f
5 q \
^ «l * ft « ^ i I ' f - i - i j ' - l f ^ t
1
' - ' -
3
^ of a substance dissolved in 100 "g of H^Q would be a' t
> cLjute-solutfon Concentfated/solutions'coiitain rela ' f tivelylatge''amounts
( of solute These teifns should ^ not be confused \vith5atuiateci and unsatuiatecP i'lB'Cegramso^fpotassiUiiiVhloiate'dissolvedmJOO'g i
' •
3
H s ' y j r * ^ T \ -*
* f 'i j. f '
- would-be saturated, 80 g*of NaN0
3
Bissolved in the < same amount of watei would be concentrated, but
.Lfnsatufated -
;
' >
? Jn'Topic2you jearnedthatdoubie-iepiacement
5 reactions" have the gerieial formula '
;LES Table F of Reference Tables
guidelines for the solubility of common ionic compounds. The table shows that all compounds of the ammonium and the nitrate ion are soluble. All of the halide ions, such as Cl~, form compounds that are soluble, but three exceptions are listed. Silver chloride is not soluble, nor are Pb
2+
nor Hg
22+
chlorides, and they are precipitates if they form in. a double-replacement reaction. This table is useful in predicting whether or not a precipitate will form when two ionic solutions are mixed. A reaction will take place if one or both of the products is listed as insoluble.
98 Topic 7
18

How does the nature of a solute and solvent affect solubility?
1. What is a polar molecule? .
2, What is a non-polar molecule?
3. What do you think is meant by the term, "Like dissolves like?"
19

Generally, "like dissolves like." Polar molecules dissolve other polar molecules and ionic compounds. Nonpolar molecules dissolve other nonpolar molecules, Alcohols, which have characteristics of both, tend to dissolve in both types of solvents, but will not dissoh ionic solids.
Check the appropriate columns as to whether the solute Is soluble in a polar or nonpoia
"solvent. . • •
CCL
1, NaCI
2. L
3. ethanol
4. benzene
5. Br r
6. KNO,
7, toluene
8. CaCOHX
Chemlstry IF8766 n-"K/-iru-il

How can we determine if a compound is soluble or insoluble?
Define:
1. soluble compound
2. insoluble compound
How can we use table F to find the solubility of a substance?
1, Is NaCl soluble?
2, Is AgBr soluble?
3. Is CaCO
3
soluble?
4. Is (NH4)
2
S soluble?
21

1. Based on Reference Table F
3
which of these saturated solutions has the lowest concentration of dissolved ions?
1) NaCI(aq)
3) NiCh(aq)
2) MgCI
2
(aq)
4) AgCI(aq)
2. According to Reference Table F, which of these compounds is most soluble at 298 K arid 1 atm?
I) PbCh
3) PbCrO4
2) AgCl
4) PbCOa
3. According to Reference Table F, which substance is most soluble?
1) Agl
3) PbCh
2) CaS04
4)
4. Based on Reference Table F, which of the following compounds is least soluble in water?
I) NaCl
3)
2)
4) PbCrCU
5. Based on Reference Table F
;
which salt is
least soluble?
1} FeCO
3
3) BaCk
2) NasCOs
4) CaCh
6. Based on Reference Table F, which of the following saturated solutions Avould be the
least concentrated?
1) sodium sulfate
2) potassium sulfate .
3) copper (II) sulfate
4) barium sulfate
7. According to Reference Table F, which compound is most soluble in water?
1) BaC0
3
3) ZnCOs
2) BaS04
4) ZnSO4
8. Which compound is insoluble in water?
1) calcium bromide
2) potassium bromide
3) silver bromide
4) sodium bromide
9. Which barium salt is insoluble in water?
1) BaCOs 2) BaCh
3) Ba(ClO4)2 4) Ba(NOs)2
10- Which ion, when combined with chloride ions, CI~, forms an insoluble substance in water?
3) Pb
2+
2) Mg
2+
4)
22

^ 120
™ no
100
I 90
1 80 en o 70
OJ
3 60 o
3 50
D,
•
>v
£ 40 la
" 1 30
1/1
/
20
/
C
J
/
A
y /
/
/
•A
T O
/
/
10 20 30 40 50 60 70 80 90 100
Temperature (°C)
Figure 7-3. A solubility curve
Figure 7-3 shows four positions relative to a line of maximum solubility. Position A is below the rum line of solubility. At this position, the iperature is 35°C, and 25 g of solute X dissolve.
Because at this point the solution holds less solute than the maximum it can hold, the solution is said to be unsaturated. If there is not a temperature change, an additional 30 g can be added to bring X to position B.
Position B is on the line of maximum solubility:
A solution that contains a maximum amount of solute that will dissolve at a specific temperature is saturated. At this position, the solution contains
55 g of X. The addition of more solid solute will not result in more being dissolved. Any additional solid that is added will simply settle to the bottom of the container.
If the temperature is reduced to 20°C, only 35 g of X can dissolve. "When the temperature of the solution, at B is reduced, the most likely event is that the excess 20 g of X will precipitate, and the' solution will remain saturated at point C. On rather rare occasions, as the temperature decreases, crystals do not form and the substance may be at position D.
At position D
;
there is more solid dissolved normal. A solution that holds more solute tiEan is present in a saturated solution at that temperature is supersaturated. These solutions are quite .unstable. The addition of a single solid crystal of the"substance will cause additional solid to form, and the solution will return to a saturated ' condition. If no temperature change occurred, the solution would become saturated at point C, with
'20 g of the substance precipitating. The only way to make a supersaturated solution is to cool a saturated solution in which there are no crystals or impurities, such as dust, present.
SuLUBgLETYTABLES Table F of Reference Tables
for Physical Setting I Chemistry contains some guidelines for the solubility of common ionic compounds. The table shows that all compounds of the ammonium and the nitrate ion are soluble. All of the halide ions, such as Cl~
?
form compounds that are soluble, but three exceptions are listed. Silver chloride is not soluble, nor are Pb
24
" nor Hg
22+
chlorides, and they are precipitates if they form in a double-replacement reaction. This table is useful in predicting whether or not a precipitate will form when two ionic solutions are mixed. A reaction will take place if one or both of the products is listed as insoluble.
98 Topic?
23

14. Solubility for salt X is shown in the table below.
Temperature
(°O
10
20
30
40
50
60
Solubility gsalt-Y
100gH
2
O
5
10
1 5 -
20
30
35
Which graph most closeiy represents the data shown in the table?
RECOGNIZING UNSATURATED, SATURATED,
AND SUPERSATURATED SOLUTIONS Because solutions are clear, it is difficult to simply look at a solution and determine whether it is unsaturated, saturated, or supersaturated.
One method of recognizing the type of solution narrows the choices. If a solution contains some undissolved solute, it must be a saturated solution.
The addition of a solute crystal can also be used to determine its condition. If it dissolves, the original solution was unsaturated. If it simply falls to the bottom, the solution is saturated. If it causes additional crystals to form, the original solution.
was supersaturated.
Temperature (°C)
(1)
(3)
Temperature (°C)
(3)
Use the tables in Reference Tables for Physical
Setting/Chemistry as needed in answering the following questions.
13. Which compound's solubility decreases most rapidly as the temperature changes from 10°C to 70°C?
(1)NH
4
CI (2)NH
3
(3)HCI (4) KCI
Temperature (°C)
{2}
Temperature (°Q
(4)
15. A solution contains 14 g of KCI in 100. g of water at
40°C What is the minimum amount of KCI that must be added to make this a saturated solution? (1) 14 g
(2)19g (3)25g (4)44g
16. Which salt has the greatest change in solubility between 30°C and 50°C? (1)KN0
3
(2) KCI
(3) NaNO
3
(4) NaCI
17. Which of the following substances is least soluble in
100.gofwaterat50°C? (1) NaCI (2) KCI (3) NH
4
CI
(4) HCI
Properties of Solutions 99
24

18. A student obtained the following data in a chemistry laboratory.
Trial
1
2
3
4
Temperature
(°Q
25
32
43
48
Solubility
(gKN0
3
/100gH
2
0)
_ —
40
50
70
60
Based on the reference tables, which of the four trials listed seems to be in error? (1)1 (2)2 (3)3 (4)4
19. How many grams of the compound potassium chloride (KCI) must be dissolved in 200. g of water to make a saturated solution at 60°C?
(1)30g (2)45g (3)56g (4) 90 g
20. Which of the following is insoluble? (1) calcium chloride {2} ammonium phosphate (3) barium sulfate (4) potassium chromate
21. Which of the following is not soluble? (1) sodium chromate (2) lead(II) iodide (3) lithium hydroxide
(4) ammonium sulfate
. If solutions of sodium chromate and potassium carbonate are mixed and poured into a filter, what will pass through the filter? (1) sodium, chromate, potassium,and carbonate ions (2) sodium and carbonate ions only (3) potassium and chromate ions only
(4) water only
23. Which amount of a compound dissolved in lOO.gof
water at the stated temperature represents a solution that is saturated? (1) 20 g KCI0
3
at 80°C
(2) 40 g KIM0
3
at 25°C (3) 40 g KCl at 60°C
(4)60gNaNO
3 at40°C
One of the most important
1
methods of stating the concentration of a solution is in terms of the number of moles of solute in a given volume of solution.
The molarity (M) of a solution is the number of moles of solute in 1L of solution. The relationship is listed in Table T of Reference Tables for Physical
Setting I Chemistry.
, .__ moles of solute molarity = -pr 7—r~^—~
* liters of solution
*?rrai?*i v"''!»:;•?-'I'^'Kf '(vii.^—.i<_).w-*tij;.(o^iv^.iK(.;;::,«
1
-"' v
W ~«i ii;,:" "M"
%&zm$£i^&^^
In the previous sample problem, the molarity of the solution is 8.0 M. A liter of this solution would contain 8.0 mol of the solute, NaOH. However, in many problems, the mass of solute is given instead of the number of moles. To solve this type of problem, convert grams of solute to moles of solute and solve as above.
Because solutions are homogeneous mixtures, their compositions can vary: Sometimes, it is adequate to refer to a solution as dilute or concentrated.
However, dilute and concentrated are relative terms and are not precise regarding the amount of solute involved. In most cases it is the specific amount, or concentration, of the solute that is important. In this section you will learn several of expressing the specific concentration of in a solution.
100 Topic?
25

SOLUTIONS
Form WS8.1.3A
Name
Date Period
A factory releases clean, warm water into a stream. The stream becomes ^ rT^arm wafer fs greatly severely polluted as a result. How does this happen? Fish living in the water I ,
a
|Jesse^or S
6 depend on dissolved oxygen in order to breathe. Like other gases, oxygen - - - - - •-°fe-"_. •••"* —^ molecules tend to spread out. In order to dissolve them, it is necessary to confine them. Heat speeds the molecules up and makes them spread out more-exactly the opposite of what is needed to dissolve them. As a result, heat drives the oxygen out of the water, causing the fish to die. The dead fish begin to decay. Growing decay bacteria deplete the water of oxygen even further. In this way, clean warm water can pollute a stream. The process of dissolving gases is opposite to the process of dissolving solids because of the differences between gases and solids.
Answer the questions below based on your reading above and on your knowledge of chemistry.
1. A warm can of soda is dropped and bounces down a flight of stairs. When it is opened, carbon dioxide gas coming out of solution causes it to spray all over. Explain the affect of each of the following: a. The fact that the soda was warm.
b. The fact that the soda was dropped and bounced down a flight of Stan's.
c. The fact that the can was opened.
2. When a gas dissolves, the particles need to be confined. What do the particles of a solid need to do in order to dissolve? .
3. Sugar is added to a hot cup of coffee and stirred. The sugar dissolves. Explain the affect of each of the following: a. The fact that the coffee was hot. .
b. The fact that the coffee was stirred.
Continue
26

: Form W S 8 . 1 . 3 A
SOLUTIONS
4. Which dissolves faster, a teaspoon of sugar or a sugar cube? Why?
Dissolving Solids and Gases
Page 2
5. A solid is added to water and stirred. Some of it dissolves, but not all. What happens to the rate at which the solid is dissolving between when it was first added and when it stopped dissolving? Explain. (HINT:
Equilibrium!) .
6. The table below lists four factors that may effect the rate at which solids and gases dissolve. Fill in the table by indicating if the rate of dissolving increases, decreases, or is not effected. Then explain why.
Factor
Solid Solutes
Affect on Rate of Solution for:
Gaseous Solutes
Crushing
Stirring
Increasing the amount of dissolved solute
Increasing
Temperature
Evan P. Silberstein, 2003
27

What does concentration mean?
How concentrated Is a solution?
Distinguish between dilute and concentrated
Define Molarity
What is the Molarity formula?
Solve the following and show all work:
1. What is the molarity of a solution containing 4.0 moles of NaOH in 0,50 L of solution?
2, What is the molarity of a solution containing 82.0g moles of Ca(NO
3
)2 in 2,0 L of solution?
1. What is the molarity of a KP( aq)
solution containing 116g of KF in 1.0 L of solution?
28

Wi
!i$
MOLAR1TY (M)
Molnritv - motes Of solute
litero{SO
Ut
Solve the problems below.
1. What is the rnoiarity of a solution in- which 58 g of .NaCI are dissolved in 1.0 L of solution?
• . r. ':
'.^ii
: m
|, f
.y
i 'i
!
'4;yi
2. What Is the molarity of a solution in which "lO.Og of AgNO
3
is dissolved in 500. ml of solution?
-3. How many grams of KNO, should be used to prepare 2.00 L of a 0.500 M solution?
4. To what volume should 5.0 g of KCI be diluted^in order to prepare a 0.25 M solution?
5. How many grams of CuSO
4
*5H
2
O are'needed to prepare 100, ml of a 0.10 M solution?
29

1
: Form WS 8 . 2 . 2A
SOLUTIONS
Name
Date Period
One of the most useful measures of concentration in chemistry is molarity (M). Molarity is the number of moles of solute per liter of solution. A two molar (2 M) solution contains two moles of solute per liter of solution.
Recall that the number of moles is determined by dividing the number of grams by the gram formula mass (GFM). There are a number of formulas for calculation that come from these relationships:
moles = M x L g=M* GFM x L
GFMx L
A two molar solution
Below are some sample problems that show how to apply these formulas.
Sample Problem 1
Find the molarity of 100. mL of a solution that contains
0,25 moles of dissolved solute.
Step 1: Convert all volumes to liters
\mL
Step 2: Substitute values into the definitional equation
Sample Problem 2
Find the molarity of 500. mL of a solution that contains
4.9 g of dissolved sulfuric acid (H
2
SO
4
).
Step 1: Find the GFM
H = 1 x 2 = 2
. S =32 x 1 = 3 2
O =16 x 4 = 64
Step 2: Convert all volumes to liters
SQO.jnL x -^~—- = 0500Z
ImL
Step 3: Substitute values into the correct equation
= O.IOM
GFMxL
r A
Sample Problem 3
How many moles of solute are dissolved in 250. mL of a
3.0 M solution?
Step 1: Convert all volumes to liters
.
ImL
Step 2: Substitute values into the correct equation
mol = M x L = (3.0»%)(0^50i) = Q.lSmol
Sample Problem 4
How many grams of sodium carbonate(Na2CO
3
) are needed to prepare 250 mL of a 0.10 M solution?
Step 1: Find the GFM
Na = 23
C = 12
0 = 16
Step 2: Convert all volumes to liters
Step 3; Substitute values into the correct equation
30

SOLUTIONS
Form W S 8 . 2 . 2 A Molarity
Page 2
Answer the questions below based on the reading and the sample problems on the previous page.
1. Determine the molarity of 500. mL of a solution with
0.35 mol of dissolved solute.
6. What is the molarity of 300 mL of a solution that contains 0,60 mol of dissolved ammonia?
2. A 200. mL sample of a solution contains 4.0 g of NaOH.
What is its molarity?
7. What is the molarity of 5.0 L of a solution containing
200. g of dissolved CaCO
3
?
3. How many grams of KNO
3
are needed to prepare 25 mL of a 2.0 M solution?
8. How many grams of NaCl are needed to prepare 500.
mL of a 0.400 M solution?
4. How many moles of MgS0
4
are contained in 50. mL of a 3.OM solution?
9. How many moles of solute are contained in 3.0 L of a
1.5 M solution?
5. How many grams of CaCl
2
are dissolved in a 0.75 M solution?
).0 mL of 10. What is the molarity of 750 mL of a solution that contains 40.0 g of dissolved CuS0
4
?
Evan P. Silberstein, 2003
31

1
1
2
2
.3, .To what volume should 25 ml of 15 M nitric acid be diluted to prepare a 3,0 M solution?
Chemistrv !F8766 AO

How concentrated is a solution in Parts Per Million?
When do we use pprn? .
What is the ppm formula?
Note: Do not forget to convert between kg, g, or mg.
Solve the following and show all work:
1. A CuSO
4
solution contains 0,050 g of CuSO
4
dissolved in 1000 g of a solution. What is the concentration in ppm?
2. Calculate the grams of fluoride ion in a 1250 grams of a fluoride ion solution having
4.0ppm concentration.
3. Approximately 0.0043g of oxygen can be dissolved in 100.0 ml of water at 20°C.
Express this in terms of ppm.
33

: Fo rm L s 8 . 2 A
SOLUTIONS
Name
Date Period to calculate the concentration of a solution, including molarity, percent, and ppm
Concentration
•k Definition:
Concentration =
Mass of solute(g)
Volume of Solvent or Solution(mL}
* Molarity
•& definition: moles(solute)
L(solutiori) related equations if M=
g
GFM,L
moles = M x £ moles
M
* GFM examples
Sample Problem 1
Find the molarity of 100 mL of a solution that contains
0.25 moles of dissolved solute.
Step 1: Convert all volumes to liters l O Q m L x 1L =0.1L
lUUUniL
Step 2: Substitute values into the definitional equation
M= moles = Q..25 moles = 2.5
M
L 0.1 L
Sample Problem 2
Find the molarity of 250 mL of a solution that contains 4 g of dissolved sodium hydroxide (NaOH).
Step 1: Find the GFM
Na = 23 x 1
O =16 x 1
H = 1 x 1
= 23
= 16
40~
Step 2: Convert all volumes to liters
250 mL x 1L = 0.25 L lOuumL
Step 3: Substitute values into the correct equation
M= g = 4g = 0 , 4 M
GFM xL 40 g/raole x 0.25 L
Sample Problem 3
How many moles of solute are dissolved in 30 mL of a
2 M solution?
Step 1: Convert all volumes to liters
30 mL x 1L = 0.03 L
1000 mL
Step 2: Substitute values into the correct equation moles = M x L = (2 moles/L)(0.03 L) = 0.06 moles
Sample Problem 4
How many grams of silver nitrate (AgNO
3
) are needed to prepare 200 mL of a 0.1 M solution?
Step 1: Find the GFM
Ag =108 x
N = 14 x
O = 16 x
= 108
= 14
170
Step 2: Convert all volumes to liters
200 mL x 1L = 0.2 L
1000 mL
Step 3: Substitute values into the correct equation g = M x GFM x L =
(0.1 mole/L)(170g/mole)(0.2 L) *= 3.4 g
Percent solution and parts per million (ppm)
•& Percent by mass: mass (solute) percent mass = mass (solution) x 100%
Sample Problem
What is the percent by mass of a solution containing 2.3 g of ethanol CC
3
HjOH) dissolved in 10.0 g of water?
Step 1: Find the mass of the solution
10.0 g +2.3g =123g
Step 2: Divide the mass of the solute by the mass of the solution and multiply by 100%
J percent mass = x 100% - 19%
34

SOLUTIONS
Form L s 8 . 2 A
Of Percent by volume: volume (solute) ,
n
_ ri
,
percent volume = x 100% volume (solution)
Sample Problem
What is the percent by volume of a solution containing
18.2 mL of glycerine (C
3
H
6
O
3
) dissolved in 85.0 mL of water?
Step 1: Find the volume of the solution.
18.2 rnL +85.0mL = 103.2 mL
Step 2: Divide the volume of the solute by the volume of the solution and multiply by 100%
percent volume - —'——- x 100% = 17.6%
W32mL
Quantities in Solutions
Page 2
Parts per million mass(solute)
ppm ~ mass(solution) x l,QQO,QOQppm
Sampje Problem
About 0.0035 g of hydrogen sulfide are dissolved in
10.0 g of water. Express this in parts per million.
Step 1: Find the mass of the solution
10.0 g + 0.0035 g = 10.0035 g
Step 2: Divide the mass of the solute by the mass of the solution and multiply by 1,000,000 ppm.
0-0035*
i n r
= 350ppm
10.0035^
Answer the questions below by circling the number of the correct response
1. How many grams of H2S04 are contained in 1,00 liter of 0.500 M sulfuric add? (1)22.4 (2)98,0 (3)49.0 (4)196
2. In a 2.0 M solution of KOH, how many moies of KOH are contained in
500 milliters of the solution? (1)1 (2)2(3)0.5(4)4
3. If 0.25 mole of sodium chloride is dissolved in a liter of solution, the molarityof the solution would be (1) 1M (2) 0.50 M (3) 0,25 M
(4) 0.125 M
4. If 0.5 liter of water is added to 0.5 liter of 2,0 m KBr solution, the molarityof the resulting solution will be (1)1.0 (2)2.0 (3)0.5
(4)1.5
5. 29 grams of NaCI are added to enough water to make 1,000. ml of solution. What is the molarity of the solution? (1) 1.00 M
(2) 0.29 M (3) 0.50 M (4) 5.00 M
6. What is the molarity of a solution of hydrochloric acid that contains
3.65 grams of HCI dissolved in 1.0 liter of solution? (1) 0.10 M
(2) 0,20 M (3) 0.80 M (4) 0.40 M
7. A1 M solution contains 40 grams of a compound in 500 ml of solution. What is the molecular mass of this compound? (1) 20
(2) 40 (3) 60 (4) 80
8. A 500 ml solution containing 28 grams of KOH is diluted with water to 1,000. ml. What is the molarity of the resulting solution? (1)1.0
M (2) 2.0 M (3) 0.25 M (4) 0.50 M
9. One liter of a sodium hydroxide solution contains 100 grams of
NaOH. The molarity of the solution is (1J1.0M (2)0.25M
(3) 2.5 M (4) 0.50 M
1 0. When 20.0 grams of NaOH is dissolved in 500 ml of solution, the concentration of the solution is (1)1.0M (2J20M (3) 0.50 M
(4) 4.0 M
11. If 49 grams of pure H2S04 are added to enough water to make
1 ,000 ml of solution, what is the moiarity of the solution? (1 ) 1 .0 M
(2) 0.25 M (3) 0.50 M (4)0.10M
1 2. The number of moles of KCI in 1 ,000 ml of 3 molar solution is
(1)1 ( 2 ) 2 ( 3 ) 3 (4)1.5
13. How many moles of ^804 are present in 250 ml of a 2.00 M solution? (1)0.50 (2)2.00 (3)1.25 (4)8.00
14. If 500 ml of 1 .0 M H2S04 is diluted with H20 to a new volume of
1, 000 mL, the molarity of the new solution is (1)1.0 (2)2.0
(3) 0,25 (4) 0.50
15. One liter of a solution of nitric acid contains 1 26 grams of solution.
The molarity of the solution is (1)1.00 (2)2.00 (3)1.26 (4)0.500
1 6. How much ethanol C^OH must be added to water to make 1 .0
liter of 0.5 molar solution of ethanol? (1)0.5 gram (2) 46 grams
(3) 23 grams (4) 92 grams
17. What mass of NaOH (formula mass - 40 g,) is needed to prepare
500 ml of 0.50 M solution? (1)10. grams (2) 20 grams (3)25 grams (4) 40 grams
1 8. Two liters of a solution of sulfuric acid contain 98 grams of H2S04.
The molarity of this solution is (1)1.0 (2)2,0 (2)0.50(4)1.5
1 9. How many moles of AgNOs are dissolved in 1 0 ml of a 1 M
AgN0
3
? (1) 1 (2) 0.1 (3) 0.01 (4) 0.001
Evan P. Silberstein, 2003
35

Molarity and PPM Worksheet
Show all work. Name:
1. What is the molarity of a solution containing 3 moles of sodium chloride in 0.5 L of solution?
2. How many moles of calcium chloride is needed to prepare 0.25M of a 2000ml solution?
3. What is the molarity of a solution containing 29g of NaCl in 1L solution?
36

4. What is the molarity of a solution containing 57g of MgF2 in 500ml solution?
5. If the amount of dissolved oxygen in water is 0.005g in 75 ml of water. What does this represent in ppm?
6. What is the concentration expressed in Parts per million of a solution containing 15.0
grams of KN0
3
in 65.0 grams of EfeO?
37

How do you express concentration of a solution in Percent by Mass?
Percent by Mass is very similar to Percent Composition, We use the same formula, but we are looking to determine concentration of solutions, not percentages of a molecule.
What is the percent composition formula?
What do we use for Percent by Mass? , . .
Solve the following and show all work:
1. What is the percent by mass of NaCl if 19.0g of NaCl is Dissolved in enough water to make 175 g of solution?
2. What is the percent by mass concentration of a solution where 5.0g of salt are dissolved inSO.Ogof water?
3, What is percent by mass of NaOH if 2.5g is added to 50.0g of water?
38

8. A student obtained the following data in a chemistry laboratory.
Trial
1
2
3
4
Temperature
25
32
43
43
Solubility
(g KNO/1 00 g H^O)
40
50
70
60
Based on the reference tables, which of the fourtrials listed seems to be in error? (1)1 (2)2 (3)3 (4)4
19. How many grams of the compound potassium chloride (KCI) must be dissolved in 200.g of water to make a saturated solution at 60°C?
(1)30g (2)45g (3)56g (4)90g
20. Which of the following is insoluble? (1) calcium chloride (2) ammonium phosphate (3) barium sulfate (4) potassium chromate
21. Which ofthefollowing is not soluble? (1)sodium chromate (2) lead(II) iodide (3) lithium hydroxide
(4) ammonium sulfate
If solutions of sodiurn chromate and potassium carbonate are mixed and poured into a filter, what will pass through the filter? (1) sodium, chromate, potassium, and carbonate ions (2) sodium and carbonate ions only (3) potassium and chromate ions only
(4) water only
23. Which amount of a compound dissolved in lOO.gof
water at the stated temperature represents a solution that is saturated? (1) 20 g KCI0
3
at 80°C
(2) 40 g KNO
3
at 25°C (3) 40 g KCI at 60°C
(4)60gNaNO,at40°C
One of the most importanfrmethods of stating the concentration of a solution is in terms of the number of moles of solute in a given volume of solution.
The molarity (M) of a solution is the number of moles of solute in 1L of solution. The relationship is listed in Table T of Reference Tables for Physical
Setting I Chemistry.
\v — nioles of solute y
~ liters of solution
In the previous sample problem, the molarity of the solution is 8.0 M. A liter of this solution would contain 8.0 mol of the solute, NaOH. However, in many problems, the mass of solute is given instead of the numher of moles. To solve this type of problem, convert grams of solute to moles of solute and solve as above.
Because solutions are homogeneous mixtures, their compositions can vary: Sometimes, it is adequate to refer to a solution as dilute or concentrated.
However, dilute and concentrated are relative terms and are not precise regarding the amount of solute involved. In most cases it is the specific amount, or concentration, of the solute that is important. In this section you will learn several of expressing the specific concentration of in a solution.
100 Topic 7
39

It is conunon to find labels that list the concentration of the ingredients by percent mass. Fertilizers often list the active ingredients as a percentage of the entire mass of the fertilizer. Percent mass is simply the mass of an ingredient divided by the total mass, expressed as a percent (parts per hundred). Percent mass problems are essentially the same as the percent composition problems found in
Topic 3. To calculate the percent mass, use the following relationship.
mass of part , „
nftn
, r
-mass of whole
40
When two liquids are mixed to form a solution, it is common to express the concentration of the solute as a percent by volume. A label on a bottle of rubbing alcohol shows a common example. Usually the label will show that the solution is 70% isopropyl alcohol by volume. The rest of the solution is
Percent by volume is the ratio of the volume o an ingredient divided by the total volume and expressed as a percent.
. . volume of solute
v
~ nnn
, percent by volume = —: -,——; x 100%
^ * volume of solution
Properties of Solutions 101

!
s per roiUiori is similar to percent composition
% is a ratio between the mass of a solute and the total mass of the solution. This method of reporting concentrations is useful for extremely dilute solutions when molarity and percent mass would be difficult to interpret. For example, chlorine is used as a disinfectant in swimming pools. Only about
2 g of chlorine per 1,000,000 g of swimming pool water is necessary to keep the pool sanitized.
Finding molarity and percent mass would result in numbers too small to be useful. Parts per million is often used to report a measured amount of air or water pollutants.
Percent composition uses the amount present per hundred parts because it is a percent. The only difference in finding ppm is that you multiply by
1,000,000 ppm instead of 100 percent.
ppm = — grams of soiute „ - . _ „„„ a grams GI soiiuion
•
It is important to be able to calculate the amount of solute to be added to a known volume of solvent to make a solution of specified concentration. The
•wing sample problem shows you how to detere the amount of solute needed to prepare a solution of known molarity.
You now know how much solute and solvent you need to actually prepare the solution in the sample problem, but the procedure used in preparation is also essential. The steps outlined below are specific for the solution used in the sample problem, but they apply to the preparation of any solution of known concentration.
First, add 53.0 g of sodium carbonate to a
2.00-L volumetric flask. Then, add some distilled water and swirl until the solute is dissolved and thoroughly mixed. Finally, nil with distilled water to the mark on the neck of the flask, and again stir to make sure the solution is homogeneous. The reason the water is added in two steps is that it is easier to dissolve the solute if the flask: is not full and there is room for the water to be adequately stirred or shaken.
102 Topic?
41

24. What is the molarity of a Kf(aq] solution containing
116 g of KF in 1.00 L of solution? (1J1.00M
(2) ZOOM (3) 3.00 M (4}4.00 M
25. What is the molarity of an H
2
S0
4
solution if 0.25 !_ of tHe solution contains 0.75 mol of H
2
SO
4
? (1) 033 M
(2) 0.75 M (3)3.0M (4) 6.0 M
26. What is the total number of moles of the solute
H
2
S0
4
needed to prepare 5.0 L of a 2.OM solution ofH
2
S0
4
? (1)2.5 mol (2) 5.0 rnol (3) 10. mo!
(4) 20. mol
27. What volume of a 2.0 M solution is needed to provide
0.50 mol of NaOH? (1)0.251 (2) 0.50 L (3J1.0L
(4) 2.0 L
28. What is the molarity of a solution that contains 40. g of NaOH in 0.50 L of solution? (1)1.0M (2J2.0M
(3) 0.50 M (4) 0.25 M
29. If 100. mL of a 1.0 M solution is evaporated to a volume of 25 ml, what will be the concentration of the resulting solution? (1)0.25M (2) 0.50 M (3J2.0M
(4) 4.0 M
30. What is the percent by mass of a solution in which
60. g of NaOH are dissolved in sufficient water to make TOO g of solution? (1)16% (2)40% (3)60%
(4) 160%
31. What is the percent by mass of a solution ff60.gof
acetic acid are added to 90.g of water? (l) 20%
(2) 30% (3) 40% (4) 67%
32. Carbon dioxide gas has a solubility of 0.0972 g/100 g
H
2
0 at 40°C Expressed in parts per million,this concentration is closest to (1) 0.972 ppm (2) 9.72 ppm
{3)97.2ppm (4) 972 ppm
33. A substance has a solubility of 350 ppm. How many grams of the substance are present in 1.0 L of a saturated solution? (1) 0.0350 g (2) 0.350 g (3) 3.50 g
(4) 35.0 g
Use the reference tables and your knowledge of chemistry to answer each of the following questions.
Be sure to show all work if calculations are needed.
34. What is the percent mass of a saturated solution of
KCI0
3 at20°C?
35. A saturated solution of ammonium chloride in 100. g
H
2
0 at 85°C is cooled to 20°C and filtered. What was the.mass of the solution af 85°C? What is the mass of the liquid that passes through the filter?
36. Barium sulfate is listed as insoluble on solubility tables. It does, however, dissolve to a small extent Its solubility at 50°C is 0.00034 g in lOO.g of water.
Express this solubility in parts per million.
37. The table below gives the solubility of Ca(OH)
2
(s) in lOO.g of H
2
0 at various temperatures. What is unusual about the behavior of the solubility of this salt?
Temperature
(°O
0
20
40
60
80
Solubility
(gCa(OH)/100.g H
2
0)
0.189
0.173
0.141
0.121
0.094
The freezing and boiling points of water change when nonvolatile solutes are added. When any salt is added to water, the freezing point of the water decreases. This helps explain why salt is applied to roads and sidewalks when, they are covered with snow and ice. The added salt lowers the freezing point and helps to melt the snow or ice. The amount of the lowering of the freezing point is dependent on the nature of the added particle. One mole of any particles will have the same effect on the freezing point. One mole of particles lowers the freezing point of 1000 g of water by 1.86°C.
When one mole of sugar, a molecular substance, is dissolved in water, one mole of particles is produced in solution.
p TT r\x P TT O (rtn\T iw/ ~7 12"^^2 11^ ^'
1 mol 1 mol
When one mole of an ionic substance is dissolved in water, the results are different. The ionic substance separates into individual ions.
NaCl(s) —» Na*(og) + Cl~(a£)
1 mol NaCl ^ 1 mol Na^ + 1 mol Cl"
Thus, one mole of sodium chloride produces two moles of particles and will depress the freezing point of water twice as much as the mole of sugar. The greater the number of ions., the greater the effect the freezing point. CaCl
2
contains three ions, and' one mole of this salt will depress the freezing point three times as much as a mole of sugar.
Properties of Solutions 103
42

What is the effect of a solute on Boiling Point Elevation and Freezing Point Depression?
Why do we pour salt on the ground in the winter? .
Changes in BP and FP follow these rnles.
Rule#l
Rule #2
Compare how will each of the following arYect the BP or FP of water?
NaCl
MgCl
2
A1
2
0
3
43

: Form N8 . 3A
SOLUTIONS
Name
Date Period to explain boiling point elevation and freezing point depression
Colligative properties - effect of solute on solvent due to the number of particles
~k Nature of colligative properties
-& Not affected by the properties of the solute, but only by the number of particles
•& Electrolytes dissociate producing more particles per mole than nonelectrolytes
"& therefor electrolytes produce larger colligative affects than nonelectrolytes
if Examples
ik Boiling point elevation - nonvolatile solute reduces the vapor pressure of water, raising the boiling point
if molal boiling point elevation = 0.5 12°C/m
•& Freezing point depression - the presence of solute interferes with crystallization, lowering the freezing point
if molal freezing point depression = L86°C/m
Answer the questions below by circling the number of the correct response
1. A pupil dissolved 180.00 grams of CgH^Og in 1,000.0 grams of water and then heated the solution until it boiled. What was the boiling point of the CgH^Oe solution? (air pressure is 1 atmosphere) (1)98,96°C (2)100.52°C (3) 99.48°C (4) 101.04°C
2. One mole of an ionic salt will usually depress the freezing point of water to a greater extent than one mole of a soluble organic substance because the ionic salt
(1) will produce more particles in solution
(2} is more easily hydrated
(3) has a higher melting point
(4) has a higher molecular mass
The solutions described in questions 3 - 9 have the same concentration of dissolved solute.
3. Which solution would have the lowest freezing point? (1) NaCI(aq)
(2) HCl(aq) (3) KCI(aq) (4) CaCI
2
(aq)
4. Which solution will have the lowest freezing point?
(1)CH
3
COOH (2}C
6
H
12
0
6
(3) C
2
H
5
OH (4) H
2
S0
4
5. Which water solution will have the lowest freezing point?
(1) BaCl2 (2) Nad (3) C
3
H5(OH)
3
(4) CH
3
COOH
6. Which water solution will have the lowest freezing point?
(1}CaCl2 £2}Ci2H22°11 (3) NaCI (4) COCOON
7. Which solution
(1)KN0
3
(2)AI(N0
3
)
3 have the highest boiling point?
(3) Mg{N0
3
)
2
(4)
Which solution has the lowest freezing point?
(1) acetic acid (3) nitrous acid
(2) potassium hydroxide (4) ammonium hydroxide
9. Which water solution
(1) CaCI
2
(2) NaCI have the highest freezing point?
(3)C
12
H
2
20n
(4) CHsCOOH
10, If 46,0 grams of ethanol C2H50H are completely dissolved in
1,000. g of water, the freezing point of the solution in Celsius is mostnearly (1)3,72 (2)-1.86 (3)1.86 (4)-3.72
11, The solution with the lowest freezing point would be produced when 1.0 gram of CgH^Og is dissolved ' n
(1) 18 grams of H20 (3) 180 grams of H20
(2) 100 grams of H
2
0 (4) 1,000 grams of H
2
0
12, What is the total number of grams of C^2°Q ^at must be dissolved in 1,000 grams of water to raise the boiling point
0.52°C? (boiling point elevation constant of H20 = 0.52°C)
(1)9 (3)18
(2)90 (4)180
Evan P. Silberstein, 2003
44

: Form WS8 . 3 , 1A
SOLUTIONS
Name
Date Period
After a winter storm, people spread salt on the walks to help melt the ice.
Salt reduces the freezing point of water. Actually, any soluble solute reduces the freezing point of water by interfering with crystallization. In this way, antifreeze keeps the water from freezing in an automobile
These are saity and cold!
radiator. This phenomenon is called freezing point depression. Antifreeze is left in the radiator during the summer. It also prevents the radiator from boiling over by raising the boiling point. Dissolved solute reduces the vapor pressure, raising the boiling point. This is called boiling point elevation.
Va por pressure exerted by water
Vapor pressure exerted by solute
The amount the freezing point is depressed or the boiling couldn't ftgbi the barbecue, soi thought,
" extra.salt , would-make them .cnert in
.your mouth!
point is raised depends on the concentration of dissolved solute. The higher the concentration of dissolved
Dad misinterprets freezing point depression.
solute is, the greater the effect on the boiling point or the freezing point is. Only the concentration of the particles of dissolved solute is important. The nature of the solute is not A mole of dissolved sugar has exactly the same effect on the freezing point and boiling point of 1,000 g of water as a mole of antifreeze because it contains the same number of particles. Ionic compounds dissociate producing more particles per mole. One mole of dissolved sodium chloride, for example, produces one mole of aqueous sodium ions and one mole of aqueous chloride ions for a total of two moles [NaCl(s) —*-Na
+
(ag) -t- Cl~(aq)], One mole of dissolved sodium chloride, therefore, has twice the effect on the boiling and freezing points of 1,000 g of water as one mole of dissolved sugar.
It is not the nature of the solute that matters, but only the concentration of dissolved particles that determines how large the change in freezing point or boiling point will be. Properties of a solution, such as this, which are dependent only on the number of particles in solution, and not on their nature are called colligative properties.
Answer the questions below based on your reading and on your knowledge of chemistry.
1. Why are boiling point elevation and freezing point depression considered colligative properties?
2. Why is salt put on icy roads and sidewalks in the winter?
3. How will the boiling points of pure water and sea water compare? Why?
Continue
45

24. What is the molarity of a KF(aq) solution containing
116 g of KF in 1.00 L of solution? (1) 1.00 M
(2) 2.00 M (3) 3.00 M (4) 4.00 M
25. What is the molarity of an H
2
SO
4
solution if 0.25 L of the solution contains 0.75 mol of H
2
SO
4
? (1) 0.33 M
(2) 0.75 M (3)3.0M (4) 6.0 M
26. What is the total number of moles of the solute
H
2
S0
4
needed to prepare 5.0 L of a 2.0 M solution ofH
2
5O
4
? (1)2.5 mol (2) 5.0 mo! (3) 10. mo I
(4) 20. mol
27. What volume of a 2.0 M solution is needed to provide
0.50mo!ofNaOH? (1)0.25L (2) 0.50 L (3J1.0L
(4) 2.0 L
28. What is the molarity of a solution that contains 40. g of NaOH in 0.50 L of solution? (1)1.0M (2)2.0M
(3) 0.50 M (4) 0.25 M
29. If 100. ml of a 1.0 M solution is evaporated to a volume of 25 m L, what will be the concentration of the resulting solution? (1)0.25M (2) 0.50 M (3)2.0M
(4) 4.0 M
30. What is the percent by mass of a solution in which
60. g of NaOH are dissolved in sufficient water to makelOOgofsoiution? (1)16% (2)40% (3)60%
(4)160%
31. What is the percent by mass of a solution if 60. g of acetic acid are added to 90.g of water? (1) 20%
(2) 30% (3) 40% (4) 67%
32. Carbon dioxide gas has a solubility of 0.0972 g/100 g
H
2
0 at 40°C Expressed in parts per million, this concentration is closest to (1) 0.972 ppm (2)9.72ppm
(3)97.2pptn (4) 972 ppm
33. A substance has a solubility of 350 pprn.How many grams of the substance are present in 1.0 L of a saturated solution? (1) 0.0350 g (2) 0.350 g (3) 3.50 g
(4) 35.0 g
Use the reference tables and your knowledge of chemistry to answer each of the following questions.
Be sure to show all work if calculations are needed.
34. What is the percent mass of a saturated solution of
KCl0
3 at20°C?
35. A saturated solution of ammonium chloride in lOO.g
H
2
0 at 85°C is cooled to 20°C and filtered.What was the.mass of the solution at'85°C? What is the mass of the liquid that passes through the filter?
46
36. Barium suifate is listed as insoluble on solubility tables. It does, however, dissolve to a small extent, solubility at 50°C is 0.00034 g in 100. g of water.
Express this solubility in parts per million.
37. The table below gives the solubility of Ca(OH)
2
(s) in
100. g of H
2
0 at various temperatures. What is unusual aboutthe behavior of the solubility of this salt?
Temperature ro
0
20
40
60
80
Solubility
(gCa(OH)/!OO.g
H
2
0)
0.189
0.173
0.141
0.121
0.094
Ttie freezing and boiling points of water change when nonvolatile solutes are added. When any salt is added to water, the freezing point of the water decreases. This helps explain why salt is applied to roads and sidewalks when they are covered with snow and ice. The added salt lowers the point and helps to melt the snow or ice. The amount of the lowering of the freezing point is not dependent on the nature of the added particle. One mole of any particles will have the same effect on the freezing point. One mole of particles lowers the freezing point of 1000 g of water by l.S6°G.
"When one mole of sugaf duced in solution.
r
a molecular substance, is dissolved hi water, one mole of particles is pro-
1 mol 1 mol
When one mole of an ionic substance is dissolved in water, the results are different. The ionic substance separates into rndividual ions.
NaCKs) -» Na
+
(ag) + Cl"(aq)
1 mol NaCl -> 1 mol Na+ + 1 mol 01"
Thus, one mole of sodium chloride produces two moles of particles and will depress the freezing point of water twice as much as the mole of sugar. The ^^ greater the number of ions, the greater the effectlM the freezing point. CaC^ contains three ions, and_ one mole of this salt will depress the freezing point three times as much as a mole of sugar.
Properties of Solutions 103

*
The situation, is similar with the boiling point.
e mole of particles will elevate the boiling point of
)0. g of water by 0.52
D
C. One mole of dissolved sugar will elevate the boiling point of 1000. g of water by 0.52°C, while one mole of dissolved sodium chloride will elevate the temperature of the same amount of water by 1.04°C.
gen, nitrogen, or fluorine, the force of attraction holding them in the liquid phase are hydrogen bonds.
38. Why is salt (NaCl) put on icy roads and sidewalks in the winter? (1 ) It is ionic and lowers the freezing point of water. (2) It is ionic and raises the freezing point of water. (3) it is covalent and lowers the freezing point of water. (4) It is covalent and raises the freezing point of water.
39. What occurs as a salt dissolves in water? (T)The number of ions in the solution decreases,and the freezing point decreases. (2) The number of ions in the solution decreases,and the freezing point increases. (3) The number of ions in the solution increases, and the freezing point decreases.
(4) The number of ions in the solution increases, and the freezing point increases.
40. Assume equal aqueous concentrations of each of the following substances. Which has the lowest freezing point? 0)C
2
H
12
0
6
(2)CH
3
OH (3) (4) NaOH
41. What occurs when sugar is added to water? (l)The freezing point of the water will decrease, and the boiling point will decrease. (2) The freezing point of the water will decrease,and the boiling point will increase. (3) The freezing point of the water will increase,and the boiling point will decrease.
(4) The freezing point of the water will increase, and the boiling point will increase.
42. Which solution has the highest boiling point?
Ol)1.0M'KNO
3
{2)2.0MKN0
3
(3) 1.0 M Ca(NO
3
)
2
(4}2.0MCa(N0
3
)
2
43. Which property of a distilled water solution will not be affected by adding 50 mLofCH
3
OH to lOO.mL
of the water solution at25°C? (1) conductivity
(2) mass (3) freezing point (4) boiling point
Tne molecules in a liquid are held together by rather weak forces. Polar molecules called dipoles are held in the-liquid- phase- by dipole-dipole- forces-.
In molecules containing hydrogen and one of oxy-
104 Topic 7
In any sample of a liquid, some of the particles at the surface have sufficient energy to escape from their neighboring molecules and enter the gas phase. When a substance that is normally a solid or a liquid at room temperature enters the gas phase it is called a vapor. Thus, you will often hear about water vapor or gasoline vapor, as water and gasoline are normally liquids at room temperature.
As the temperature of a liquid increases, the particles have more energy, and more particles escape from the surface. These vapor particles are gaseous particles and exert pressure in the gaseous phase. The pressure that a vapor exerts is called
.vapor pressure. Table H of Reference Tables for
Physical Setting/Chemistry is a graph showing the vapor pressure of four substances measured in pressure units of kilopascals (kPa).
Of the substances shown on the graph, propanone exerts the most pressure, about 93 kPa at a temperature of 50°C. It can be inferred that propanone has the weakest interrnolecular forces holding it in the liquid phase, while ethanoic acid lias the greatest, exerting only about 8 kPa of pressure.
As the temperature of a liquid rises, vapor pressure increases. Finally the vapor pressure becomes equal to atmospheric pressure. At this point trie gas may vaporize, not only on the surface but at any point in the container. A bubble of vapor below the surface has enough pressure that it does not collapse from the atmospheric pressure pushing against it. When a bubble can occur at any point in the liquid, the process is called boiling. The normal
boiling point of a liquid is the temperature at which the vapor pressure of the liquid is 101.3 kPa, standard atmospheric pressure. Equivalent pressures are 1 abn, 760 mm Hg, and 760 torr.
47

T^e.heat required to change 1 mol of a substance from a liquid at its boiling point to 1 mol of a vapor is termed the heat of vaporization.
The normal boiling point of water is 100.°C. At this temperature, the vapor pressure of water is
101.3 kPa. The line representing 101.3 kPa on
Table H shows the normal boiling point of ethanol to be 78°G. When the pressure is less than
101.3 kPa, the boiling point will be less than the normal value. Water will boil at about 70°C when the pressure is about 30 kPa. If the pressure is greater than normal, liquids will boil at temperatures above their normal boiling points. When atmospheric pressure is about 145 kPa, water boils at 110.°C.
Use the tables in Reference Tables for Physical
Setting/Chemistry as needed in answering the following questions.
44. What is the vapor pressure of water at 105°C?
(1)100kPa (2)101.3 kPa (3)110kPa (4}120kPa
45. As the pressure on a liquid is changed from lOO.kPa
to 120. kPa, the temperature at which the liq uid will boil (1) decreases (2) increases (3) remains the same (4) depends on the liquid
46. In a closed system at40°C,a liquid has a vapor pressure of 50 kPa.The liquid's normal boiling point could be (1)10°C (2)30°C (3)40°C (4) 60°C
47. If the pressure on the surface of water in the liquid state is 30 kPa, the water will boil at (1)0°C (2)30°C
(3)70°C (4)100°C
48. A sample of ethanoic acid at 100°C has a vapor pressure of (1)53kPa (2}100kPa (3)101.3kPa
(4)125kPa
49. Which substance has the greatest interrnolecular forces of attraction between molecules?
(l)propanone (2) ethanol (3) water
(4) ethanoic acid
50. The vapor pressure of ethanol at its normal boiling point would be (1)30kPa (2)101.3kPa (3)273kPa
(4) 373 kPa
Use the tables in Reference Tables for Physical
Setting/Chemistry as needed in answering the following questions.
1. When a teaspoon of sugar is added to water in a beaker,the sugar dissolves.The resulting mixture is
(1) a compound
(2) a homogeneous solution
(3) a heterogeneous solution
(4) an emulsion
2. A small quantity of a salt is stirred into a liter of water until it dissolves. In the resulting mixture,the water is
(1) the solvent
(2) the solute
(3) dispersed material
(4) a precipitate
3. A solution
(1) will separate on standing
(2) may have color
(3) can be cloudy
(4) can be heterogeneous
4. Nonpolar solvents will most easily dissolve solids that are
(1) ionic
(2) covalent
(3) metallic
(4) heterogeneous
5. What happens when a crystal of a salt is dropped into an unsaturated solution of the same salt?
(1) Excess solute crystals form.
(2) The crystal dissolves.
(3) The crystal drops to the bottom, unchanged.
(4) The solution becomes colorless.
Properties of Solutions 105
48

Electrolytes are substances that break up (dissociate or ionize) in water to produce ions.
These tons are capable of conducting an electric current.
Generally, electrolytes consist of acids, bases and salts (ionic compounds),
Nonelectrolytes are usually covalent compounds, with the exception of acids.
Classify the following 'compounds as either an electrolyte or a nonelectrolyte.
1, NaCI
2. CH,OH (methyl alcohol)
3-, C,H,(OH), (glycerol) i
4. HC!
5. C
A
H
19
O
A
(sugar)
6. .NaOH
7. C,H fi
OH (ethyl alcohol)
'2
1
'5
8, CH,COOH (acetic acid) o
9. NH
4
OH (NH
3
+ H
2
O)
10. H
2
S0
4
Chemistry IF8766
49
72
©Instructional Fair,

• Which of the following substances are likely to be soluble in water?
• Write the reaction that happens when each soluble substance in is dissolved in water,
• Is the substance an electrolyte?
.. Ba(NOA ll.Hg,(C10A
12. K
3
P0
4
2. ZnS
3. (NHACCX
4. Fe
2
0
3 14.NH
4
NO
3
5.
15.ZnCrO
6. NaCIO,
16.MSO,
7. BaCrO
4
8. FeBr,
9. Ag,SO
2 4
10. Ca(OH),
17. Aid
IS.AgI
19. CaBr.
20. CuS
50

The heat required to change 1 mol of a substance from a liquid at its boiling point to 1 mol of a vapor is termed the heat of vaporization.
The normal boiling point of water is 100.°C. At this temperature, the vapor pressure of water is
101.3 kPa. The line representing 101.3 kPa on
Table H shows the normal boiling point of ethanol to be 78°C. When the pressure is less than
101.3 kPa, the boiling point will be less than the normal value. Water will boil at about 70°C when the pressure is about 30 kPa. If the pressure is greater than normal, liquids will boil at temperatures above their normal boiling points. When atmospheric pressure is about 145 kPa, water boils at IIO.'C.
Use the tables in Reference Tables for Physical
Setting/Chemistry as needed in answering the following questions.
44. What is the vapor pressureofwaterat 105°C?
(l)lOOkPa (2)1013kPa (3)110kPa (4)120kPa
45. As the pressure on a liquid is changed from lOO.kPa
to 120. kPa, the temperature at which the liquid will boil (1) decreases (2) increases (3) remains the same (4) depends on the liquid
46. In a closed system at40°C,a liquid has a vapor pressure of 50 kPa.The liquid's normal boiling point could be (1)10°C (2)30°C (3)40°C (4) 60°C
47. If the pressure on the surface of water in the liquid state is 30 kPa,the water will boil at (1)0°C (2}30°C
(3)70°C (4)100°C
48. A sample of ethanoic acid at 100°C has a vapor pressureof (1)53kPa {2)100 kPa (3)101.3 kPa
(4)125kPa
49. Which substance has the greatest intermolecular forces of attraction between molecules?
(l)propanone (2) ethanol (3) water
(4) ethanoic acid
50. The vapor pressure of ethanol at its normal boiling pointwouldbe (1)80kPa (2)101.3kPa (3)273kPa
(4) 373 kPa
Use the tables in Reference Tables for Physical
Setting/Chemistry as needed in answering the following questions.
1. When a teaspoon of sugar is added to water in a beaker, the sugar dissolves.The resulting mixture is
(1) a compound
(2) a homogeneous solution
(3) a heterogeneous solution
(4) an emulsion
2. A small quantity of a salt is stirred into a liter of water until it dissolves. In the resulting mixture, the water is
(1) the solvent
(2) the solute
(3) dispersed material
(4) a precipitate
3. A solution
(1) will separate on standing
(2) may have color
(3) can be cloudy
(4) can be heterogeneous
4. Nonpoiar solvents will most easily dissolve solids that are
(1) ionic
(2) covalent
(3) metallic
(4) heterogeneous
5. What happens when a crystal of a salt is dropped into an unsaturated solution of the same salt?
(1) Excess solute crystals form.
(2) The crystal dissolves.
(3) Trje crystal drops to the bottom, unchanged.
(4) The solution becomes colorless.
Properties of Solutions 105
51

6. The depression of the freezing point is dependent on
(1) the nature of the solute _ _ t
(2) the formula mass of the solute
(3) the concentration of dissolved particles
(4) hydrogen bonding
7. The process of recovering a salt from a solution by evaporating the solvent is known as
(1) crystallization
(2) filtration
(3) reduction
(4) decomposition
8. What happens when a crystal of solute is dropped into a supersaturated solution of the salt?
(1) The crystal dissolves.
(2) Excess solute crystals form.
(3) The crystal drops to the bottom, unchanged.
(4) The solution begins to boil
9. Under which conditions are gases most soluble in water?
{1) high temperature and high pressure
(2) high temperature and low pressure
(3) low temperature and high pressure
(4) low temperature and iow pressure
10. As the temperature of a liquid decreases, the amount of a gas that can be dissolved
(1) decreases
(2) increases
(3) remains the same
(4) depends on the identity of the gas
11. As the temperature of liquid water decreases, its vapor pressure
(1) decreases
(2) increases
(3) remains the same
(4) disappears
12. The heat energy required to change one mole of a liquid into a vapor at the boiling point is called the
(1) heat of vaporization
(2) heat of formation
(3) heat of solution
(4) heat of fusion
13. Which substance increases in solubility as the temperature decreases?
(1)KCI0
3
(2) NH
3
(3) KN0
3
(4) NaC!
14. The diagrams below represent an ionic crystal being dissolved in water.
Ionic crystal
Water molecule
According to the diagrams, the dissolving process takes place by
(1) hydrogen bond formation
(2) metallic bonding
(3) dipole-dipole attractions
(4) molecule-ion attractions
15. If solutions of barium nitrate and sodium sulfate are mixed and then poured into a filter, the solid remaining on the filter will be
(1) barium nitrate
(2) sodium nitrate
(3) barium sulfate
(4) sodium sulfate
16. A student tested the solubility of a salt at different temperatures and then used the ReferenceTablesfor
Physical Setting/Chemistry to identify the saltThe student's data appears below.
Temperature
C°c)
30
50
62
76
Solubility Data
(g of salt per 10 g of water)
1.2
2.2
3.0
4.0
What is the identity of the salt?
(1) potassium nitrate
(2) sodium chloride
(3) potassium chlorate
(4) ammonium chloride
106 Topic 7
52

17. If IQO.g of water at 80°C contains 45 _g of KCJ and
45 g of NalMO
3
,the solution is
(1) saturated with respect to both KCI and NaNO
3
(2) saturated with respect to KCI and unsaturated with respect to NaNO
3
(3) unsaturated with respect to both KCI and NaN0
3
(4) supersaturated with respect to both KCI and
NaNO
3
18. What happens when Kl(s) is dissolved in water?
(1) l~ ions are attracted to the oxygen atoms of the water.
(2) K
+
ions are attracted to the oxygen atoms of the water.
(3) K
+
ions are attracted to the hydrogen atoms of the water.
(4) No attractions are involved; the crystal just falls apart.
19. A student drops a crystal of NaCI into a beaker of
NaCl(aq) and the crystal dissoIves.The original solution must have been
(1) supersaturated
(2) saturated
(3) unsaturated
(4) heterogeneous
20. Which two compounds contain only polar molecules?
(1)CCI
4 andCH
4
(2)HClandCl
2
(3)HClandNH
3
(4) CO and CO
2
21. A saturated solution of potassium chloride at 10°C is heated to 30°C As the solution is heated in a closed container, the total mass of the solution
(1) decreases
(2) increases
(3) remains the same
(4) depends on the pressure
22. Water boils at 90°C when the pressure exerted on the liquid equals
(1)82kPa
(2) 90 kPa
(3)l01.3kPa
(4)120kPa
23. Considerthefollowing data for NaCi:
Temperature (°C)
Solubility (g/1 00 gH
2
0)
0
35.7
20
36.0
50
37.0
TOO
39.2
When the salt is added to water,the temperature of the solution decreases.Which of the following statements is correct?
(1) The process is endothermic, and solubility and temperature are directly related.
(2) The process is endothermic, and solubility and temperature are indirectly related.
(3) The process is exothermic, and solubility and temperature are directly related.
(4) The process Is exothermic, and solubility and temperature are indirectly related.
24. Which sample of ethanol will have the highest vapor pressure?
(1)10.mLat62°C
(2) 20.0 ml at 52°C
(3)30.mLat42°C
(4) 40 ml at 32°C
25. The vapor pressure of water is 50 kPa.The temperature of this sample of water is
(1)37°C
(2) 62°C
(3) 82°C
(4) 92°C
Show all work for problems 26-30.
26. What is the percent mass of NaOH if.12.5 g is dissolved in 100, g of water?
27. What volume of 3.0 M HCl contains 0.20 mol of HC1?
28. A swimming pool reading reports that chlorine is present at 30 ppm. How many grams of chlorine are present per liter of poo! water?
29. What is the molarity of a solution that contains 24 g of NaNO
3
in 200 ml of solution?
30. How many grams of KNO
3
are present in 250 ml of
2.0 M potassium nitrate solution?
Properties of Solutions 107
53

31. Describe two methods by which you could remove gases that are dissolved in water. [2]
32. Consider the following data for Na
7
5O ,
Temperature {°Q
Solubility (g/1 00 gH
2
0)
0
4.76
20
62
50
50. i
100
41
What is the relationship between the temperature and the amount of dissolved material? Given that sodium sulfate is a solid, what is unusual about the data given above? [2]
33. One moleofethanol (C
2
H
5
OH) will depress the freezing point of 1000. g of water by 1.86°C How many grams of ethanol would be needed to depress the freezing point of 1000. g of H
2
0 by 3.72
D
C? [1]
34. Describe how to prepare 500. ml of 4.0 M
Show any calculations. [2]
Use the following figure to answer questions 35 and 36.
35. The figure represents the line showing the solubility of substance X. A solution of substance X is represented by point D. What are two ways that this solution can be made saturated? [2]
36. Point B represents a supersaturated solution.
Consider the equation:
When a crystal is placed into the supersaturated solution, additional crystals form and fail to the bottom of the beaker, and the solution returns to a saturated condition. Which of the two positions shown on the line of saturation would best representthe solution when the crystals first settled to the bottom? Explain the reason for your answer. [2]
37. Substance X is a molecular substance that is soluble in water. It costs $.90/ton.Substance Y is an ionic substance that costs $ 1 .00/ton. Both have the same environmental impacts,are easy to handle,andare nontoxic. Using your knowledge of chemistry, which would be a better choice to use to melt snow on walks or driveways? Justify your answer. [2]
38. if 0,169 g of carbon dioxide can be dissolved in 100.g
of H
2
O at 20°C, what is the concentration in parts per
. million? [1]
IT
-B
~o no
TOO
90
80
70
60
50
40
30
20
10
A /
F
/
/
•
B
/
/
/
/
/
/
C
D
A
/
/
/
/
E
10 20 30 40 50 60 70 80 90 100
Temperature(°C)
TQS Topic 7
54

2, Solution containing the maximum amount of solute possible at that temperature
4. Two liquids which can mix are said to be _____ ,
6, The presence of a nonvolatile solute will the boiling • point of a solvent,
9. " A homogeneous • mixture
10. Substance present in larger amount in a
.
mixture
13. Moles of a solute per kilogram of solvent
14. Solution containing a relatively large amount of solvent
15. Jhe solubility of gases
15
' as temperature
12
19
17
17. State in which the rate of dissolving is equal to the rate of precipitation
14
13
11
10
16
. 18. The presence of a nonvolatile solute will the freezing point of a solvent,
19. These substances dissociate or ionize in.water and are then able to conduct an electric current, •
1. Properties that depend on the number of particles in solution
3. Solution in which more solute can be dissolved
5, Solution containing a relatively large amount of dissolved solute
7. Substance present in smaller amount in a mixture
8. The solubility of most solids as temperature increases.
I
I1, Maximum amount of solute that can dissolve in a stated amount of solute at a given temperature
12, Moles of solute per liter of solution
16. Solutions in which water is the solvent are called , .
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