Grade 7 Science
Unit 3: Mixtures and
Solutions
Chapter 8: Some substances dissolve to form
solutions faster and more easily than others.
Name: __________________________
1
Making Solutions
When you mix two substances they form a ____________________
Solutions have two parts
The substance that
dissolves
(found in less
amounts)
ex: sugar
The substance in
which the solute
dissolves.
(found in the
greatest amount)
Ex :water
For each situation identify the solute and the solvent:
Situation
A. Brass is used to
make many
objects. Brass is a
solution of zinc
metal in a copper
metal
Solute
Solvent
B. Hydrogen
peroxide is used
to disinfect cuts.
Hydrogen
peroxide is a
solution of 3%
hydrogen and
97% water.
C. Dental amalgam is
a metal that is
used to fill
cavities. It is a
solution of
mercury in tin.
2
D. Deicing fluid is a
cleaner used to
clean car and
truck windshields.
It is made up of a
solution of
propylene glycol
in water.
Dissolving
Definition:
Dissolve
________________________________________________________________________
________________________________________________________________________
How are substances soluble?
According to the particle theory of matter, “there are _____________forces between the
particles”. In order to dissolve the _______________must be more strongly attracted to
the solvent than to themselves. This is means the solute is ____________in the solvent.
If something is ABLE to dissolve then it is _________________________.
Ex: __________________________________________________________________
How are substances insoluble?
If the particles of the ____________ are more attracted to their own particles than the
solvent particles, ______________does not occur. The solute is said to be __________
in that solvent.
If something is UNABLE to dissolve then it is _______________________.
Ex: __________________________________________________________________
3
Soluble or Insoluble?
Solvent or not??
Some materials are good _________________ for some solutes but not for others.
For example, ____________________________________________________________
4
Complete Activity 8 -1C Page 259
“Does it Dissolve?”
Different states of matter of Solutes and solvents.
Solvents and solutes can be different states of matter.
Fill in the state of matter for each solute and solvent in the given solution
Solution
Solute
Solvent
State of solute
State of solvent
Soda water
Carbon dioxide Water
GAS
LIQUID
Vinegar
Acetic acid
Water
LIQUID
LIQUID
Salt water
salt
Water
SOLID
LIQUID
Brass
zinc
Copper
SOLID
SOLID
Concentration
(p. 262)
The two cups below each had hot water with a tea bag sitting in them. The time
below the cup indicates how long the tea bag has been in the cup.
Definition: _A solution that has a __
Definition: A solution that contains a small
large amount of dissolved solute _
amount of dissolved solute
for a certain amount of solvent.
for a certain amount of solvent.
5
Directions:
1. Supposing these were clear cups, use a brown lead to color how dark you think
the tea would be in each cup.
2. Write the statement dilute solution or concentrated solution under the cup you
think it describes.
3. Write the definition for each statement in the space provided
Describing Concentration
The quantity of ___solute___ that is dissolved in a certain quantity of the _solvent__.
Concentration can be described two ways:
Qualitatively
QuaNtitatively
“With words”
like dilute and
concentrated
“With Numbers”
such as units of grams
per litre (g/L)
Qualitative or Quantitative?
Statement
Food coloring made the
water blue.
Adding 3 mL of food
coloring turned 250 mL of
water blue.
The water became warmer.
The water’s temperature
increased by 5 degree
Celsius.
We needed just over a
dozen floor tiles for our
model room.
Qualitative
Quantitative
√
√
√
√
√
6
√
We needed 14 floor tiles
for our model room.
The liquid boiled in 5 min.
The liquid took only a few
minutes to boil.
The mass of this solid is 5g
more than that one.
This solid is heavier than
that one.
He drinks eight glasses of
water each day.
He drinks 2L of water each
day.
√
√
√
√
√
???
√
Question:
If you were a diabetic and had to watch you sugar intake, would you want to know the
concentration of a drink qualitatively or quantitatively? Why?
I would want to know the quantitative concentration of sugar in a drink because I
would need to know an exact amount so I know how much insulin to take, or how
many carbohydrates I can eat.
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1. Convert each of the following from g/mL to g/L.
a) 10 g/ 100 mL = _______________________
b) 52 g/ 100 mL = _______________________
c) 65 g/ 100 mL = _______________________
d) 100g/ 100 mL = _______________________
e) 137g/ 100 mL = _______________________
f) 0.15g/ 100 mL = _______________________
Saturated vs. Unsaturated Solution
(Refer to p.264)
Define:
Saturated Solution:
________________________________________________________________________
____________________________
____________________________
Unsaturated Solution:
__________________________________________ ______
____________________________________________________
____________________________
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WEDNESDAY, MARCH 15th
Question:
1. If there are two glasses on Kool Aid on the table, one is unsaturated the other is
saturated. How would you be able to tell the difference between the two?
-
We are going to assume that both glasses of Kool Aid are the same temperature
and color, and that they both taste the same.
We can tell the difference between the unsaturated and saturated solutions by
adding more Kool Aid powder (solute).
- If the powder dissolves, we know the solution is unsaturated.
If the powder does not dissolve, we know the solution is saturated.
2. It is possible to “unsaturate a saturated solution”. Suggest ways you might be
able to do this. (Hint: How could you make more sugar to dissolve in a glass of
water?)
We cannot change the amount of solute or solvent.
However, we can increase temperature or pressure.
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Solubility
(Refer to p. 264)
Define:
Solubility:
________________________________________________________________________
____________________________________________
Factors that effect the Rate of dissolving
Factor
A.
Size of Solute
B.
Temperature
C.
Pressure
How does it affect the solubility?
10
Grade 7 Science Core Lab Activity 8-2A Pages 268-9
Unit 3: Mixtures and Solutions
How Does Temperature Affect Solubility?
Procedure: Part 1
Refer to text page 268.
Complete the graph on the graph paper provided on the next page.
Questions:
1. Describe the shape of the lines on your graph.
2. What happens to the lines as the temperature increases?
3. Predict the solubility of each solute at 90 degrees Celsius?
Sucrose
Potassium Chlorate
Ammonium Chloride
Title: ___________________________________________________________________
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Part 2:
Name: ______________________________
Partners: ____________________________
____________________________
Problem:
____________________________
_____________________________
How does temperature affect the solubility of a solid in a liquid solvent?
Hypothesis:
Materials:
graduated cylinder
sugar cubes
thermometer
stopwatch
beaker
Procedure:
 Measure 100 mL of cold water for one beaker.
 Measure 100 mL of hot water for another beaker.
 Record the initial temperatures of both beakers.
 Drop one sugar cube in each beaker and record the amount of time it takes to
completely dissolve.
Results:
Sugar Mixture
Temperature
Temperature
(Class
Average)
Time
Time
(Class
Average)
Cold
Hot
Analyze:
How did the solubility in warmer water of the substance you tested compare with its
solubility in colder water?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
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Key Terms
Dissolves
________________________________________________________________________
________________________________________________________________________
Insoluble
________________________________________________________________________
________________________________________________________________________
Soluble
________________________________________________________________________
________________________________________________________________________
Solute
________________________________________________________________________
________________________________________________________________________
Solvent
________________________________________________________________________
________________________________________________________________________
Concentrated Solution
________________________________________________________________________
________________________________________________________________________
Concentration
________________________________________________________________________
________________________________________________________________________
Dilute Solution
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________________________________________________________________________
________________________________________________________________________
Saturated Solution
________________________________________________________________________
________________________________________________________________________
Solubility
________________________________________________________________________
________________________________________________________________________
Unsaturated Solution
________________________________________________________________________
________________________________________________________________________
Comprehension Questions
1. a) Vinegar in insoluble in vegetable oil. Does this mean that vinegar is a totally
insoluble substance?
________________________________________________________________________
b) Why or why not?
________________________________________________________________________
________________________________________________________________________
2. List two substances that are soluble in water.
i)
________________________________________________________________________
ii)
________________________________________________________________________
3. List two substances that are insoluble in water.
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i)
________________________________________________________________________
ii)
________________________________________________________________________
4. Name a substance that is insoluble in water but is soluble in a different solution.
________________________________________________________________________
5. You put 3 teaspoons of sugar in jug and you put 2 teaspoons of sugar in another jug
exactly the same size. Which jug is more concentrated?
________________________________________________________________________
6. What does the units g/L mean?
________________________________________________________________________
________________________________________________________________________
7. What is the difference between a saturated solution and an unsaturated solution?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
8. Explain this statement: “The solubility of salt is 357 g/L at 0℃.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
9. How does the size of the solute affect the rate of dissolving?
________________________________________________________________________
________________________________________________________________________
10. Refer to Table 8.2 on page 264.
a) Which is the most soluble substance? ________________________________
b) Which is the least soluble substance? ________________________________
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11. a) Suppose that you add some solid detergent to the water in a washing machine. Then,
you decide that your clothes are really dirty, so you add more detergent. Is the solution
of detergent and water more concentrated or more dilute? Explain.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Temperature (0℃)
Solubility in Water (g/L)
Sugar
Potassium
Ammonium
Chlorate
Chloride
10
1910
50
320
20
2040
70
370
30
2200
110
410
40
2390
150
460
50
2610
210
500
60
2870
270
550
70
3200
340
600
12. Using the table above, which solute has the highest solubility at each of the following
temperatures?
a) 20℃
______________________
b) 60℃
______________________
c) 90℃
______________________
13. Why must you include information about temperature when you state the solubility of a
substance?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
16
Goal • Use this word search puzzle to review Key Terms from Chapter 8.
Create a list of 11 words from the descriptions below. Then find the words in the puzzle that
follows.
1. A solution in which the amount of solute is high
compared to the amount of solvent
2. What happens to a solute such as sugar when it
is mixed with water
3. A word used to describe a substance such as
glass when it is mixed with water
4. The opposite of the term you found for number 1
5. A solution that has as much solute dissolved in it
for a given temperature
6. A word used to describe a substance such as
motor oil when it is mixed with gasoline
7. The amount of solute that will dissolve in a given
quantity of solvent at a certain temperature
8. Another name for a homogeneous mixture
9. A word used to describe a mixture such as salt
water in which you can still dissolve more salt
10. Term used for what you mix into a substance
such as water to form a solution
11. Term used for what you mix with a substance
such as salt to form a solution
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Goal • Check your understanding of Chapter 8.
What to Do
Circle the letter of the best answer.
1. Which of the following statements accurately describes a solution of copper
in silver?
A. The copper is the solute and the silver is the solvent.
B. The copper is the solution and the silver is the solvent.
C. The silver is the solute and the copper is the solvent.
D. The silver is the solution and the copper is the solvent.
2. Which of the following statements is true?
A. Chlorophyll is soluble in water.
B. Gasoline is insoluble in motor oil.
C. Gasoline is soluble in motor oil.
D. Salt is insoluble in water.
3. How is a concentrated solution different from a dilute solution?
A. The concentrated solution has a large mass of dissolved solvent for a certain
quanity of solute.
B. The concentrated solution has a large mass of dissolved solute for a certain
quantity of solvent.
C. The concentrated solution has a small mass of dissolved solute for a certain
quantity of solvent.
D. They both have different solubilities.
4. Which statement best describes what is meant by the term “rate of
dissolving?”
A. how fast a mixture must be stirred
B. how fast a solute dissolves in a solvent
C. the solubility of a substance at a given temperature
D. the temperature at which a solute dissolves in a solvent
5. What happens when you remove the cap from a bottle of pop?
A. The pressure inside the bottle lowers very quickly.
B. The pressure inside the bottle remains the same at a certain temperature.
C. The pressure inside the bottle rises very quickly.
D. The solution increases in pressure at a certain temperature.
6. At 0°C, 357 g of salt will dissolve in 1 L of water. At this temperature, why
will no additional salt dissolve?
A. The rate of dissolving is equal to its solubility.
B. The solution is concentrated.
C. The solution is saturated.
D. The solution is unsaturated.
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Match the term on the left with the best description on the right.
Each description may be used only once.
Term
_____ 7. solute
_____ 8. solubility
_____ 9. solution
_____ 10. solvent
_____ 11.saturated
_____ 12.soluble
Description
A. describes a substance that will dissolve in
another substance
B. the mass of a solute that can dissolve in a
certain amount of solvent at a certain
temperature
C. the mass of a solvent that can dissolve in a
certain solute at a certain temperature
D. the substance in which something dissolves
E. a homogeneous mixture
F. the substance that dissolves in another
substance
G. describes a solution in which no more solute
will dissolve at a certain temperature.
H. describes a solution in which no more solute
will dissolve
Short Answer Questions
13. Give examples of each of the following.
solid-in-solid solutions
(1) ______________________
(2) ______________________
liquid-in-liquid
solutions
(1) ______________________
(2) ______________________
gas-in-gas solutions
(1) ______________________
14. Use the particle theory of matter to explain why some substances are
soluble in water while other substances are not soluble in water.
_________________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
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15. Suppose that you have a solution of table salt dissolved in water. Explain
how you could find out whether or not this solution is saturated.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
16. The solubility of sugar in water is 1792 g/L at 0°C. How much sugar must be
added to 50 mL of water to make a saturated solution at 0°C?
_________________________________________________________________
_________________________________________________________________
17. The solubility of a substance can be expressed qualitatively and
quantitatively. Use examples to explain this statement for sugar dissolved in
water.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
18. In the space to the right,
sketch the shape of a graph that
shows how the solubility of sugar
in water changes as the
temperature of the water
increases. Label the axes
correctly, and title the graph.
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