嘉南中學
HOPE CHRISTIAN HIGH SCHOOL
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ELEMENTARY SCHOOL
SCIENCE DEPARTMENT
GRADE 7
First Term, SY 2013
SOLUTIONS
Module 2
LESSON 1
Solution and Its Properties
KEY CONCEPTS / SUMMARY
Solution is a homogeneous mixture
Solute and solvent are the two components of solution
Solute is the substance that Is dissolved; one in smaller proportion
Solvent is the dissolving medium; one in larger proportion
Electrolyte is a compound in an aqueous solution that conducts electricity
Non electrolyte is a compound in aqueous solution that do not conducts electricity
Aqueous solution is where solute dissolves in water
NOTES
Types of Solution
•
Gaseous solutions are usually homogeneous and all gaseous mixtures are gas-gas solutions.
The air is a natural gas-gas solution. Air is made up primarily of nitrogen (~78%) and oxygen
(~21%) with trace amounts of argon, carbon dioxide and water vapour.
Nitrogen-oxygen
gas-gas solution
•
•
Liquid solutions are our most easily recognized mixtures. When molecules of gas, solid or liquid
are dispersed and mixed with those of liquid, the homogeneous states are called liquid
solutions. Solids, liquids and gases dissolve in liquids to form liquid solutions.
Solid Solutions are much lesson common. Many alloys, ceramics, and polymer blends are solid
solutions. Copper and zinc dissolve in each other and harden to give solid solutions called
brass. Silver, gold, and copper form many different alloys with unique colors and
appearances.
Brass (alloy of copper and zinc)
Types of Solution
TYPE
SOLID
Liquid
Gas
SOLUTE
SOLVENT
EXAMPLE
gas
solid
Oxygen gas(O2) in ice
liquid
solid
Amalgam Hg in Ag (tooth fillings)
Solid
solid
Tin (Sn) in Copper (Cu) - bronze
gas
liquid
Oxygen gas(O2) in moist water
liquid
liquid
Ethyl alcohol in water - wine
solid
liquid
Sugar in water
gas
gas
CO2 in N2 - air
liquid
gas
Moisture loaded air
Solid
gas
Naphthalene ball in air
Forming a Solution
A solution is only formed when two substances mix homogeneously, meaning that any portion of the
solution will contain a specific amount of both the solute and the solvent. In the cases of cereal and
milk or of muddy water, the two substances in the mixture will settle apart into two layers over time, so
they are not homogeneously mixed. When you are dealing with a true solution, the two (or more)
substances found in the solution will never settle apart.
Not every combination of two substances becomes a solution. When you pour milk on your cereal in
the morning, the resulting mixture is not a solution because the cereal does not become dissolved in
the milk. Similarly, when mud in water causes turbidity, the mud is not part of a solution. We use the
term insoluble to describe two substances which do not form a solution when they are mixed
together.
Solutes and Solvents
In each solution, the solvent is the substance which determines the state of the finished solution.
since the resulting solution is a liquid. If both the solute and the solvent have the same state, the
solvent is typically the part of the solution which is present in the highest concentration.
Universal Solvents
Water is sometimes called the universal solvent because of its ability to dissolve a diverse array of
substances. Acetone is also occasionally referred to as a universal solvent since it is able to dissolve
oils, alcohols, and water. In truth, however, there is no such thing as a universal solvent because no
one substance is capable of dissolving every possible solute.
Even though there is no true universal solvent, you use one very good solvent every day - soap. Soap
is made up of molecules which act like an oil on one end and like an alcohol on the other, so they
are soluble in oils, in water, and in alcohol.
WORKSHEET #1
A. Which of the following are solutions? Write Yes for solution and No if it is not a solution.
_____ 1. milk
_____ 2. apple juice
_____ 3. the gas in a helium-filled balloon
_____ 4. distilled water
_____ 5. rain water
_____ 6. smoke- filled air
_____ 7. stainless steel
B. Complete the table.
SOLUTION
SOLUTE
SOLVENT
PHYSICAL STATE
(solid, liquid or gas)
Vinegar ( 5.0 % acetic acid)
18 –K gold ring
Brass (20% Zn, 70% Cu)
Cl
(chlorine gas) in swimming
pool
Carbonated drink/Softdrink
Rubbing alcohol (70%
isopropyl alcohol)
WORKSHEET #2
View the item or read the description at each of the 18 samples and complete column two of the
student worksheet by including both the station number and example observed at the station. It is
important to consider what the constituents of the solution are (solid, liquid or gas solute in solid liquid
or gas solvent). In third column, determine which substance is acting as the solute and which is
acting as the solvent at the station observed.
Sample Description:
Sample #1: A bottle of household vinegar (5%
liquid acetic acid dissolved in water)
Sample #3: Solid Air Freshener subliming into
the air when heated
Sample #2: Sugar cubes dissolving in water
Sample #4: Hydrogen dissolving in a transition
metal such as platinum (a hydrogen storage
strategy for releasing hydrogen for H2-powered
vehicles).
Sample #5: A brass candle holder (brass is an alloy
of the solids copper and zinc)
Sample #9: Soap suds
Sample #6: A bottle of rubbing alcohol formed
from liquid alcohol and water.
Sample #13: A Styrofoam cup
Sample #7: A mercury-gold amalgam (formed
when liquid mercury is used to extract gold
from gold-bearing rock) or mercury-zinc
amalgam used in tooth fillings.
Sample #14: The atmosphere above the water
when water evaporates in a sealed water cooler
container
Sample #15: Smoke (solid particulates being
released into the air) resulting from a fire
Sample #8: Seawater
Sample #10: A Car tire (made up of solid
carbon in rubber)
Sample #16: A bottle of antifreeze (liquid
ethylene glycol in water)
Sample #11: A piece of (cheap) jewelry made
up of copper and gold
Sample #17: Kool-Aid powder poured into
water
Sample #12: Methane gas released from the
valve in a chemistry lab into the air
Sample #18: Food coloring diffusing into water
Use the SAMPLE DESCRIPTION to record your data.
Type of Solution
(solute-solvent)
gas-solid
Sample #
State which substance is the solute and
solvent for Station # listed
gas-liquid
gas-gas
liquid-solid
liquid-liquid
liquid-gas
solid-solid
solid-liquid
solid-gas
WORKSHEET 3
A. Identify the type of solution (solid solution, liquid solution, gas solution)
____________ 1. air in solid food (ex: generic ice-cream)
____________ 2. carbon dioxide in water (Pepsi™)
____________ 3. oxygen in nitrogen (air)
____________ 4. mercury in silver-tin dental alloy
____________ 5. various hydrocarbons in each other (petroleum)
____________ 6. water vapour in air (humidity)
____________ 7. carbon in iron (steel)
____________ 8. ammonium nitrate in water (ice-packs
B. Fill in the Blanks: Types of Solutions
1.
2.
3.
4.
5.
6.
gas in _______________
____________ in liquid
__________ in ___________
gas in __________________
Liquid in ________________
___________ in __________
carbonated beverages
alcohol in water
salt in water
hydrogen in platinum
mercury in silver (dental fillings)
copper in silver (sterling silver)
LESSON 2
Solubility
KEY CONCEPTS / SUMMARY
Solubility is the maximum amount of solute dissolved in a given amount of solvent at a
specified temperature
Liquids that are capable of forming solution is called miscible, those that do not mix to
form solution are immiscible
Factors that affect solubility are: Properties of solute and solvent, temperature and
Pressure
Factors that affect the rate at which substance dissolve are: Particle size,
Agitation/stirring, Increase in temperature and Concentration of solution
NOTES
Solubility and Saturation
A variety of units can be used to measure the concentration of solute in a solution. In
general, a concentrated solution is one where the amount of solute in a given volume
of solvent is great. A dilute solution is one where the amount of solute in a given
volume of solvent is relatively small. But can we mix up a solution of any
concentration? For example, can we produce a 90% solution of table salt in water?
How about a 90% solution of table salt in gasoline?
A few substances are infinitely soluble, or miscible, which means that they can be
mixed together in any proportion. Ethyl alcohol and water are an example of miscible
substances since they can be mixed together in concentrations ranging from pure
alcohol to pure water. However, most substances are not infinitely soluble.
Solubility is a term used to describe the amount of solute which can be dissolved in a
solvent. The solubility of two substances will depend on the similarity of the two
substances. As mentioned on the last page, some substances (such as oil and water)
have a solubility of close to zero. Most substances, however, will have a solubility
somewhere between complete insolubility and complete miscibility.
Factors Influencing Solubility
The solubility of two substances depends on several factors in addition to the identity of
the substances. These factors can include characteristics of the environment and the
state of the solute and solvent. In every case, these factors will influence the amount of
solute which can be dissolved in a solvent.
Environmental factors which influence solubility include temperature and pressure. For
example, warm air is able to dissolve much more water vapor than cold air can. You
may have noticed that the air is humid (full of water vapor) only on warm days. If very
humid air cools suddenly, the extra water vapor will fall out of solution and will turn into
liquid water. The liquid water in the air forms clouds or fog.
The solubility of a solute can also depend on its oxidation state, which refers to the
amount of electrons found in the substance. For example, iron and manganese tend
to enter water in a low oxidation state, meaning that they have a relatively large
number of electrons. But when these metals are exposed to air, they become oxidized
(lose electrons) and are no longer very soluble in water. So the oxidized metals drop
out of solution and cause red or black water complaints as well as stains on sinks and
clothes.
Saturation: Unsaturated, Saturated and Supersaturated
An unsaturated solution is one that can still dissolve more solute at that temperature.
A saturated solution is one in which the solute in solution is in equilibrium with the pure
undissolved solute; in other words, the solution contains all of the solute it can dissolve at
that particular temperature.
Once a solution has reached the limit of the solute's and solvent's solubility, the solution
is said to be saturated, meaning that it can hold no more solute. If additional solute is
added to a saturated solution, the extra solute will settle out, forming a separate layer
like the kind you would see when two substances are insoluble.
A saturated solution of table salt and water.
You can form your own saturated solution of table salt and water as follows. Add salt to
water, stirring constantly until the salt dissolves. At first, the salt will completely dissolve in
the water, discoloring the water slightly but leaving no visible solid residue. However,
once you have added a certain amount of salt to the water, the solution becomes
saturated. When you add more salt past the saturation point, the salt will not dissolve
into the water no matter how long you mix the solution. Instead, the extra salt will settle
out in a layer at the bottom of the solution as shown above.
Supersaturation
Whenever a solution contains more solute than it can hold, it is said to be
supersaturated. We have mentioned one supersaturated solution already in this lesson the warm air which cooled and thus contained more water vapor than it could hold.
A supersaturated solution contains more solute in solution than it would ordinarily hold
at that temperature. Example: If in hot coffee one dissolves all the sugar it can possibly
hold and carefully cools it, the coffee still holds all the sugar that was dissolved and a
supersaturated solution exists. If a small crystal of sugar is introduced into this cooled
coffee, some sugar will crystallize out and a saturated solution will remain
Solutions can become supersaturated in a variety of ways, but in every case the
supersaturated solution is unstable. If more of the solute is added or if the conditions
change in any way, the extra solute will settle out of the supersaturated solution. In the
water vapor and air solution, dust particles in the air provided the slight change which
caused water vapor to settle out, forming clouds and rain.
If you've ever made sweetened iced tea, you will have taken advantage of the
characteristics of a supersaturated solution. By adding sugar to hot tea, you were able
to dissolve much more sugar into the water than you would have been able to dissolve
into cold tea. When the tea cooled, the additional sugar remained dissolved in the tea
as a supersaturated solution. If you tried to add more sugar to the cooled tea,
however, the excess solute would drop out of solution and the tea would become less
sweet.
WORKSHEET #3
Use the data table below to answer the following questions.
Substance
Sinks to the bottom
Sand
√
Floats on top
Floats in the liquid
Sodium Nitrate
Disappears
√
Sulfur powder
√
Table salt
√
Copper sulfate
√
PROBLEM
√
√
1. Name two insoluble substances
________________________________________________________
2. Name two soluble substances
________________________________________________________
3. Name one substance which forms a suspension
_______________________________________________
4. Name two substances which dissolved
_______________________________________________________
5. What is the name given to the mixture of copper sulfate and
water?______________________________________________________________________________
CHECK YOUR UNDERSTANDING
Underline the letter of the correct answer.
1. If a solution can hold more solute (it isn't full yet) it is:
A.
Unsaturated
B.
Saturated
C.
Supersaturated
2. If a solution cannot hold any more solute (it is full) it is:
A.
Unsaturated
B.
Saturated
C.
Supersaturated
3. If a solution holds more solute than it should be able (its over full) it is:
A.
Unsaturated
B.
Saturated
C.
Supersaturated
4. A solution is saturated at 25 g per 100g of H2O. If 25 grams is dissolved in 100g of
H2O, it is:
A.
Unsaturated
B.
Saturated
C.
Supersaturated
5. A solution is saturated at 25 g per 100g of H2O and holds 22 grams in 100g of H2O.
It is:
A.
Unsaturated
B.
Saturated
C.
Supersaturated
6. A solution is saturated at 25 g per 100g of H2O and holds 31 grams in 100g of H2O.
It is:
A.
Unsaturated
B.
Saturated
C.
Supersaturated
7. A solution can hold 10 grams per 100g of H2O. If 8 g is dissolved in 100g of H2O of
water, it is:
A.
Unsaturated
B.
Saturated
C.
Supersaturated
8. A solution can hold 15 grams per 100g of H2O. If it holds 30 g in 200g of H2O of
water, it is:
A.
Unsaturated
B.
Saturated
C.
Supersaturated
9. A solution can hold 12 grams per 100g of H2O. If it holds 35 g in 200g of H2O of
water, it is:
A.
Unsaturated
B.
Saturated
C.
Supersaturated
10. A solution can hold 9 grams per 100g of H2O. If it holds 15 g in 200g of H2O of
water, it is:
A.
Unsaturated
B.
Saturated
C.
Supersaturated
LESSON 3
CONCENTRATIONS
KEY CONCEPTS / SUMMARY
Concentration of solution expresses the amount of solute dissolved in a given quantity
of solvent. Concentration can be express in different ways.
Percent by Mass/Weight
% m/m = mass of solute / mass of solution x 100
Percent by Volume
% v/v = volume of solute / volume of solution x 100
Percent by Mass / Volume
% m/v = mass of solute / volume of solution
NOTES
Layering
The layering seen in a solution which has passed its saturation point resembles the
layering seen when two insoluble substances are mixed. But, as you can see in the
illustration below, these two situations are actually quite different. One of the layers in
the saturated solution contains both solute and solvent while the layers in the insoluble
mixture contain only one substance per layer.
The extra solute added to a saturated solution may settle either to the top or to the
bottom of the solution. The location of the extra solute depends on its density, a
concept we will discuss in a later lesson.
Dilution
In lab, you will often be given a stock solution which you will need to dilute to a given
concentration for use in a lab exercise. Dilution consists of adding more solvent to a
solution so that the concentration of the solute becomes lower. The total number of
solutes in the solution remains the same after dilution, but the volume of the solution
becomes greater, resulting in a lower molarity, ppm, mg/L, or % concentration.
In the picture above, I've shown the solute as yellow dots and the solvent as solid blue.
The 1 L beaker on the left shows the initial concentration, which we might represent as
13 dots/L. The beaker on the right is the result of dilution of the left beaker. We added
more solvent so that the solution's total volume was 3 L. As a result, the concentration
of the diluted beaker is (13 dots)/(3 L), or 4.3 dots/L.
Predicting the factors that affect rate of dissolving
How would you
increase the rate at
which the sugar
dissolves?
How would you
decrease the rate
at which the sugar
dissolves?




Temperature
Factor
Agitation
Particle Size
Increase
Increase
Decrease
Decrease
Decrease
Increase
Temperature and Solubility
Solubility data always includes the temperature... why? → Temperature
greatly affects solubility
re: energy is required to break the bonds holding a solid together → higher
temperature provides this energy i.e. caffeine solubility @ 25C = 2.2.g/100mL;
@ 100C = 40g/100mL
Temperature is less important when we discuss the solubility of a liquid... why?
→ Bonds holding the liquid together are not as strong
How would you expect temperature to affect the solubility of a gas? → Being
dissolved in a liquid limits the high kinetic energy of a gas, therefore solubility
of a gas decreases with increased temperature\
Pressure and Solubility
 Pressure not as important in the solubility of solids and liquids as it is for gases
 example: why do you hear the sound of escaping gas when you open the lid
of a carbonated drink? → pressure in the sealed bottle is much higher than
atmospheric therefore solubility of the carbon dioxide is much higher opening it decreases the pressure to atmospheric and carbon dioxide
becomes less soluble
PERCENT COMPOSITION
PERCENT =
PART
WHOLE
x 100
1. Percent - Mass in a total volume
(m/v) Most frequently used form of %.
A 5% solution means 5 grams in 100 mL volume. Or 2.5 grams in 50 mL volume.
A 5 mg% solution means 5 mg in 100 mL volume. Same as 5 mg/dL. (dL = 100 mL
2. Percent- Mass of solute and mass of solution (m/m)
This refers to the amount of solute in grams in the total solution also in grams.
Example: A 10% aqueous NaCl solution contains 10 g of NaCl in 90 g of water (or 10 g
NaCl
per 100 g of solution).
3. Percent - Volume of solute in volume of solution. (v/v)
This refers to relative amounts of two liquids in solution. Example: An alcoholic
beverage that
is 7% alcohol contains 7 ml of alcohol per 100 ml of solution.
Ratios of individual liquids is generally given rather than %. Example: A
chromatography
solvent was chloroform: methanol: water
(6:3:1).
Problems
1. How many grams of sugar are needed to make 100 ml of a 20% solution?
2. What is the concentration in mg % of 100 mg of NaCl dissolved in 500 ml of solution?
3. How many grams of sugar are needed to make 150 ml of a 30% solution:
4. I have 250 ml of a .9% NaCl solution (saline). How many grams of salt do
I have ?
5. How many grams of sugar are need to make 50 grams of a 3% solution?
MOLAR SOLUTIONS
Molar solutions are used more frequently and are more precise
than the percent solutions.
Molarity =
moles
liters
1. How would I make up 500 mL of a 1 M solution of NaCl?
moles
=
grams
Molarity =
MW
moles
L
1
=
x moles
0.5 L
x =
0.5
=
0.5 moles
x grams
58.5
x = 29.25 grams
Put 29.25 g NaCl in flask, stir, add H2O and bring up to 500 ml
2. How would we make up 250 mL of a 3 M solution of NaCl?
3. How much NaCl would I need to make up 10 ml of a 6 M solution?
4. How many grams of Ca(CO3) would I need for 100 ml of a 2 M solution?
5. I have 29.25 g NaCl in 500 ml. What is its molarity?
LABORATORY ACTIVITY
TESTING HYPOTHESIS ON DISSOLVING
Your task is to create and test a hypothesis concerning what kind of solution dissolve in each
other. For each of the suggested chemical systems choose two liquids as solvent. You are to
complete the Hypothesis, Prediction, Analysis and Evaluation. Submit a written report of your
experiment.
QUESTION
Do water, table salt, table sugar, kerosene, ammonia (spirit of ammonia- aromatic) and ethyl
alcohol dissolve in each other?
HYPOTHESIS
Create a testable hypothesis about what kind (classes) of substances dissolve in each other.
PREDICTION
Write a prediction based on your hypothesis. For each prediction, use your hypothesis to
provide reasoning behind the prediction.
EXPERIMENTAL DESIGN
Each of the solute is mixed with the specified liquid solvent to determine if it dissolves. Take
note that the quantities of solute, solvent, the temperature and stirring are controlled variables.
EVIDENCE
Tabulate your result
SOLVENT
SOLUTE
Table salt
Table sugar
Kerosene
Ammonia
Water
Ethyl alcohol
ANALYSIS
Answer the Question using a summary of the evidence collected.
EVALUATION
a. Are your predictions useful, falsified or inconclusive? Justify your answer by
comparing the experimental and predicted result.
b. Based on your answer to (a), is your hypothesis acceptable?
The Degree of Saturation of a Solution
Purpose:
• To prepare aqueous solutions of sodium acetate with different degrees of saturation.
• To study the properties of these solutions.
Introduction: A solute can dissolve in a given amount of solvent to give three different kinds
of solution. The resulting solution can be unsaturated (contain less solute than
the solvent is capable of holding), saturated (contain the maximum amount of
solute that the solvent is capable of holding), or supersaturated (contain more
than the amount of solute that the solvent is normally capable of holding under
the given conditions).
In this experiment, you will prepare solutions of each type, identify them, and
study some of their properties.
Apparatus: 150 mm test tubes (2)
burner
rubber stopper
250 mL beaker
test tube holder
glass stirring rod
Materials: anhydrous sodium acetate (hydrated sodium acetate)
Procedure:
A. Place 10mL of distilled water in a 150 mm test tube. Add a few milligrams (a few tiny crystals)
of anhydrous sodium acetate. OR Place 5.0mL of distilled water in a 150 mm test tube. Add a
few milligrams (a few tiny crystals) of hydrated sodium acetate. Close the test tube with a
rubber stopper and shake it vigorously for 30 s. Add a few more crystals and shake the test
tube again for another 30 seconds.
B.
Now add 8.0 g of the sodium acetate to the solution. Stopper the test tube and shake it
vigorously for 1 min. Wait 1 min to allow settling of any undissolved matter. Use a glass stirring
rod to push any solid that is above the liquid down into the liquid. Pour the clear upper liquid
into a dry test tube. To the clear liquid in the second test tube add a few crystals of anhydrous
sodium acetate, stopper, and shake vigorously for 1 min. Make very careful observations of
the test tube.
C. Allow the cold-water tap to run so that at the end of part C you will have the coldest water
possible. Pour the contents of the second test tube back into the first tube and add an
extra 2.0 g of the sodium acetate. Holding the test tube in a nearly horizontal position and
taking care not to point the open end at anyone, heat the liquid gently (by moving the test
tube in and out of the flame) to dissolve the solid present. Avoid "bumping" (sudden
irregular, bubbling) which might cause you to lose some of the contents of the test tube.
Use a glass-stirring rod to push as much solid at the top of the test tube down into the liquid.
Continue the gentle heating until all of the solid has dissolved.
D. Gently place the test tube in a beaker of cold water and allow it to remain undisturbed for 5
min. If crystals appear at any point, remove the test tube, reheat it gently to re-dissolve the
crystals, and place the test tube in water for another 5 minutes. Gently remove the test tube
and add one or two tiny crystals of the sodium acetate.
Making Sense of the DATA
1. What kind of solution did you have in part A? How do you know?
2. What kind of solution was the clear liquid that you added to the second test tube in part B?
How do you know?
3. What kind of solution did you have in part D before the crystals of the sodium acetate were
added? How do you know?
4. What kind of solution did you have in part D after the crystals were added?
5. What happens when a small particle of solute is added to an unsaturated solution? Explain.
6. What happens when a small particle of solute is added to a saturated solution? Explain.
7. What happens when a small particle of solute is added to a supersaturated solution? Explain.
Questions to Ponder
8. Why did your second test tube in part B have to be dry?
9. Devise a test to determine whether a solution is unsaturated, saturated, or supersaturated.
10. Would it be possible to form a supersaturated solution of a compound whose solubility
decreases with increasing temperature? Explain.
CHAPTER TEST
TYPE I MULTIPLE-CHOICE QUESTIONS
In each of the following multiple-choice questions, place the letter of the correct response in the
blank at the left. There is only one correct response for each question.
_____1 In a solution, the solvent is ______
a) the substance being dissolved.
b)always a liquid.
c) the substance present in the greatest amount.
d) always water.
_____2 A solution may contain _______
a)only one solvent but many solutes.
b) many solvents but only one solute.
c) only one solvent and one solute.
d)many solvents and many solutes.
_____3 a Which of the following statements concerning a saturated solution is incorrect ?
a)Undissolved solute must be present.
b)Undissolved solute may or may not be present.
c)Undissolved solute, if present, is continually dissolving.
d)Undissolved solute, if present, is in equilibrium with dissolved solute.
_____4 b Which of the following statements concerning factors that affect solute solubility is
incorrect?
a)Most solid solutes become more soluble in water with increasing temperature.
b)Most solid solutes become less soluble in water with decreasing pressure.
c)Gaseous solutes become less soluble in water with increasing temperature.
d)Gaseous solutes become more soluble in water with increasing pressure.
_____ 5. The solubility rule “like dissolves like” is not adequate for predicting solubilities when the solute
is ____
a(n)a)nonpolar gas.
c)nonpolar liquid.
b) ionic compound.
d)polar gas.
_____ 6. For which of the following types of ionic compounds are most examples insoluble in water?
a)nitrates
b)sulfates
c)phosphates
d)acetates
_____ 7. Which of the following statements about solutions is correct?
a) A solution is a homogeneous mixture.
b) It is possible to have solutions in which both solute and solvent are solids.
c) Solutions readily separate into solute and solvent if left undisturbed for 24hours.
d) (more than one correct response)no correct response
_____ 8. A crystal of solid NaCl is placed into an aqueous NaCl solution. It is observed that most, but
not all, of the crystal dissolves. This means the original solution was_______
a) supersaturated.
c) dilute.
b) unsaturated.
d) (more than one correct response)no correct response
_____ 9. Which of the following types of antiparticle attractions must be overcome in order for a
solute to dissolve in a solvent?
a)solute-solute
b)solvent-solvent
c)solute-solvent
d)more than one correct responsee)no correct response
Consider the following substances and their polarities:
A – polar, B – polar, C – nonpolar, D – nonpolar.
_____ 10. It is true that
a)A is more soluble in C than in B.
b)C is more soluble in D than in A.
c)D is more soluble in B than in C.
d)more than one correct responsee)no correct response
_____ 11. Particles of the dispersed phase in a colloidal dispersion are
a)small enough that they cannot be seen by the naked eye.
b)large enough that they settle out under the influence of gravity.
c)small enough that they cannot be filtered out using filter paper.
d)more than one correct responsee)no correct response
_____ 12. In which of the following pairs of properties are both members of the pair colligative
properties?
a)density, boiling point
b)vapor pressure, osmotic pressure
c)solubility, freezing point
d)more than one correct responsee)no correct response8
_____ 13. In which of the following pairings of terms are the terms closely related?
a)hemolysis, hypotonic solution
b)hypertonic, higher osmotic pressure than within cells
c)isotonic solution, crenation
d)more than one correct responsee)no correct response
_____ 14. Which of the following statements concerning dialysis iscorrect ?
a)Only water passes through the dialyzing membrane.
b)Dissolved ionic substances and small molecules are separated from colloidal particles.
c)Two types of colloidal particles are separated from each other.
d)more than one correct responsee)no correct response
CHOICE FORMAT TRUE-FALSE QUESTIONS
In each of the following multiple-choice questions, characterize EACH of the three given
statementsas being TRUE or FALSE and then indicate the collective true-false status of the statements
using thechoices
a) All three statements are true.
b) Two of the three statements are true.
c) Only one of the statements is true.
d) None of the statements is true.
______ 1.
a. A saturated solution always contains excess undissolved solute.
b. In aqueous solution Ba2+ion combines with NO3-ion to produce an insolub lesalt.
c. Addition of a nonvolatile solute to a solvent produces a solution with lower vapor pressure,
freezing point, and boiling point than that of pure solvent.
_____ 2.
a. Equal volumes of two solutions of the same molarity contain the same number of grams of
solute
b. Hemolysis and crenation are “opposite” processes.
c. The solubility rule “like dissolves like” is not adequate for predicting thesolubility of ionic
compounds in water.
_____ 3.
a. In a colloidal dispersion solute particles are large enough to be discernible bythe naked eye.
b. The selectivity of a semi-permeable membrane is based on polarity differencesamong
molecules.
c. For dilute aqueous solutions, %(m/m) and %(m/v) concentration units havealmost the same
magnitude because the density of water is 1.00 g/mL andthe solution is almost entirely water.
_____4.
a. TheTyndall effect involves light-scattering by colloidal-sized particles.
b. Aqueous solutions of 0.1 M KCl and 0.1 M glucose would have the samefreezing point
because the solvent is water in both cases.
c. Percent by volume is a concentration unit used when both solute and solventare liquids.
_____ 5.
a. To find the molarity of a solution, both solution volume and the number of moles of solute must
be known.
b. Osmosis involves the passage of solvent from a dilute solution (or pure solvent) into a more
concentrated solution.
c. 5.0 %(m/v) glucose solution and 0.9 %(m/v) sodium chloride solution have the same osmolarity
and are hypotonic relative to red blood cells.
Prepared By: Sheila Marie R. Visda