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Content Vocabulary
Acid and Base Solutions
Directions: An analogy is a relationship between two pairs of words. An analogy can be written in the following
manner: a is to b as c is to d. For example, apple is to fruit as celery is to vegetable. In the analogies that follow,
one of the words is missing. On each line, write the term from the word bank that correctly completes each analogy.
acid
base
1.
2. Acid is to lemon as
3. Base is to OH− as
4. H 3 O+ is to
5. Acidity is to
hydronium ion
indicator
pH
is to pH as thermometer is to temperature
is to detergent.
is to H 3 O+.
as OH− is to hydroxide ion.
as distance is to centimeter.
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Lesson Outline
Acid and Base Solutions
A. What are acids and bases?
1. Acids are found in many
, including fruits,
, milk, and vinegar; bases are also found in many
household items, such as
, baking soda, and medicines
called antacids.
2. A substance that produces a hydronium ion (H 3 O+) when it is dissolved in water is
called a(n)
.
a. Almost all acid molecules contain one or more
atoms,
which separate from the acid when they are mixed
with
.
b. The hydrogen atom combines with a water molecule to form
ion, (H 3 O+), which is a positively charge ion
a(n)
that forms when an acid dissolves in water.
3. A substance that produces hydroxide ions (OH–) when it is dissolved in water is
called a(n)
.
a. Some bases, such as sodium hydroxide, contain
when hydroxide compounds mix with
hydroxide ions
ions;
, the
from the base in the water.
b. Some bases, such as ammonia, do not contain hydroxide ions; but when these
bases mix with
, they take
+
ions (H ) away from water molecules, producing
ions
(OH–).
B. What is pH?
1. The
is an inverse measure of the concentration of
hydronium ions (H 3 O+) in a solution; the
of something
means that as one thing increases, the other thing decreases.
a. A solution that has a lower pH is more
than
a solution that has higher pH.
b. A solution that has a higher pH is more
a solution that has a lower pH.
than
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Lesson Outline continued
2. A solution that is
, such as pure water, contains an equal
number of hydronium and
ions.
ions (H 3 O+)
a. An acid has a greater concentration of
ions (OH–).
than
ions (OH–)
b. A base has a greater concentration of
ions (H 3 O+).
than
3. The
scale, which ranges from 0 to
, is used to indicate how acidic or basic a solution is.
a. A solution with a pH of 7 is
; a solution with a pH
lower than 7 is
; a solution with a pH higher than
7 is
.
b. An change of 1 unit on the
scale represents a(n)
change in the acidity or basicity of the solutions
being compared.
C. How is pH measured?
1. A compound that changes color at different pH values when it reacts with acidic or
basic solutions is called a(n)
.
2. Strips that contain a universal
a(n)
; the color change of the strip is matched against
a list that shows which colors represent which
3. Using a pH
can be dipped into
.
, which has an electrode sensitive to the
concentration of hydronium ions, is a more accurate way to measure pH than using
pH strips.
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Content Practice A
Acid and Base Solutions
Directions: Complete the concept map with the correct phrase from the word bank in the space provided. Each
phrase is used only once.
has hydroxide ions
has a pH below 7
has a bitter taste in foods
has hydronium ions
has a pH above 7
has a sour taste in foods
Solution
Facts About Acids
Directions: Respond to each statement on the lines provided.
1. List three examples of everyday acids.
2. List three examples of everyday bases.
Facts About Bases
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Content Practice B
Acid and Base Solutions
Directions: Use the diagram to answer the question on the lines provided.
Acids Mixed with Water
1. What happens when hydrochloric acid dissolves in water?
Directions: Answer each question on the lines provided.
2. What happens when a base dissolves in water?
3. What happens to the pH of a solution as the concentration of hydronium ions increases?
4. What happens to the pH of a solution as the concentration of hydronium ions decreases?
5. Why is pH an inverse measure of the concentration of hydronium ions in a solution?
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Language Arts Support
Word-Family Activity: Sentence Completion
Directions: On each line, write the form of the term that correctly completes each sentence.
1. mixed/mixture
a. Air is a
containing 78 percent nitrogen, 21 percent
oxygen, and 1 percent other substances.
b. The substances that make up granite are unevenly
.
2. solution/solute/solubility
a. Salt is a common
found in many food products.
b. Air is an example of a gaseous
.
c. More of a substance can dissolve in a given solvent if it has a
high
.
3. produce/production
a. Bases
hydroxide ions when they are dissolved in water.
b. Taking hydrogen atoms away from water results in the
of hydroxide ions.
4. saturate/saturated/saturation
a. The directions said to keep adding the solvent until the solution
reached
.
b. He kept adding orange drink powder until the solution
was
.
c. She continued to add solute, in an attempt to
the
solution.
5. indicator/indication
a. The pH scale gives you a good
as to how acidic or basic
a solution is.
b. An
is a compound that changes color at different Ph
values when it reacts with acidic or basic solutions.
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Language Arts Support
Reading Comprehension Activity
Directions: After you have read Lessons 2 and 3 of your textbook, complete the exercise below. On the line before
each question or statement, write the letter of the correct answer.
1.
is used to test the pH level in a solution.
A. A base
B. An acid
C. An indicator
2. How could a person increase the concentration of a solution?
A. by adding more solute to the solution
B. by adding more solvent to the solution
C. by putting the solution into a larger container
3. Which formula can be used to calculate concentration?
A. v =
d
t
B. C =
m
v
C. a =
F
m
4. A glass of lemonade contains 90 percent water, 7 percent lemon juice, and
3 percent sugar. Which substance is the solvent in this solution?
A. water
B. sugar
C. lemon juice
5. Air contains 78 percent nitrogen, 21 percent oxygen, and 1 percent other
substances. Which substances are the solutes in this solution?
A. nitrogen and oxygen
B. oxygen and other substances
C. nitrogen and other substances
6. Which statement is true?
A. Acid contains less H 3 O+ than OH-.
B. Bases contain less OH- than H 3 O+.
C. All acid and base solutions contain H 3 O+ and OH−.
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School to Home
Acid and Base Solutions
Directions: Complete the first table below with your learning partner. Then use your textbook to complete the
second table.
1. Look in your kitchen or bathroom for foods and products that contain acids or bases.
Record your results in the chart below. You do not have to fill every space in the table.
Acids and Bases in My House
Products or Foods Containing Acids
Products or Foods Containing Bases
2. Use the table below to record information about the properties of acids and bases. Fill
in each space in the table.
Properties of Acids and Bases
Acids
Bases
Name
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Key Concept Builder
Acid and Base Solutions
Key Concept What happens when acids and bases dissolve in water?
Directions: Complete the diagram by writing the steps that occur when an acid dissolves in water.
acid + water (H2O)
Directions: Answer each question or respond to each statement on the lines provided.
1. What does an acid produce when it is dissolved in water?
2. What do almost all acid molecules contain?
3. A hydronium ion (H3O+) is
when an acid dissolves in water.
Class
Name
Date
Key Concept Builder
Acid and Base Solutions
Key Concept What happens when acids and bases dissolve in water?
Directions: Answer the question on the lines provided.
1. How is base defined?
Directions: Use the diagram to answer each question on the lines provided.
Bases Mixed with Water
2. What happens when sodium hydroxide dissolves in water?
3. What happens when ammonia dissolves in water?
4. How is ammonia different from sodium hydroxide?
Class
Name
Date
Class
Key Concept Builder
Acid and Base Solutions
Key Concept How does the concentration of hydronium ions affect pH?
Directions: On each line, write the term from the word bank that correctly completes each sentence. Some terms
may be used more than once.
acidic
basic
hydronium
hydroxide
inverse
neutral
pH
solution
1.
means that as one thing increases, another thing decreases.
2. For the safety of all swimmers, it is important for pool water to have the
correct
.
3. A(n)
measure of the concentration of hydronium ions
in a solution defines pH.
4. When the concentration of
ions increases, the pH decreases.
5. A solution with a lower pH is more
.
6. A solution with a higher pH is more
.
7. An acid is distinguished from a base by a higher amount of
ions than hydroxide ions.
8. Bases are distinguished from an acid by a higher amount of
ions than hydronium ions.
9. A change from one pH unit to another pH unit represents a ten-fold change in how
acidic or basic a(n)
is.
10. Solutions that have a pH of 7 are not acidic or basic; they are referred to
as
.
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Key Concept Builder
Acid and Base Solutions
Key Concept What methods can be used to measure pH?
Directions: Complete the chart on the lines provided.
pH Indicators
pH Testing Strips
1. An indicator is a molecule
whose color depends on
pH Meters
5. This method of measuring
pH uses
9. The most accurate method
of testing pH is to use a
.
.
6. A universal indicator is one
that
10. A pH meter is an electronic
instrument that has an
electrode that is sensitive
to the
.
2. When using a pH indicator, a
drop or two of the indicator is
.
.
7. To use pH testing strips, first
.
11. Acids have a pH below 7,
and bases have a pH
3. The change in the color of
the solution is then
compared to a set of
.
8. Then match the color on the
strip to
on the pH scale.
12. The pH meter indicates
the concentration of
.
4. Each indicator changes color
over a specific range of
.
in solution.
.
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Enrichment
pH and Health
You may be surprised to learn that the
liquid that digests food in your stomach is
about a million times more acidic than
pure water. Hydrochloric acid in the stomach
has a pH of about 1–2. This would eat
through many metals! However, the stomach
lining secretes mucus, which protects the
stomach walls as the acid breaks apart food
during digestion. The low pH also kills many
harmful organisms that might be in the food.
Despite the low pH of the stomach, the
pH balance of the body is much closer to
neutral. This balance is extremely important
to health. The pH level determines the speed
of chemical reactions by controlling the speed
of enzyme activity, as well as the speed of
electrical impulses that move through the
body. If the overall pH of the body is acidic,
reactions take place quickly. When the pH is
alkaline, reactions take place much more
slowly.
Effects of pH
Many people today tend to eat lots of
acidic foods, such as coffee, burgers,
carbonated beverages, and pizza. These foods
lower the pH of the body and cause chemical
reactions to take place very quickly. Initially,
people have lots of energy, but it quickly
fades. In addition to being tired, people can
become irritable.
What’s normal?
The pH of human blood should be
slightly alkaline (7.35–7.45). If blood pH
goes below 6.8 or above 7.8, cells stop
functioning. If your body’s pH is not
balanced, for example, you cannot
effectively absorb vitamins, minerals and
food supplements. A pH below 7 can also
decrease the energy production in the cells,
decrease the body’s ability to repair
damaged cells, encourage the growth of
tumor cells, and make the body more
susceptible to fatigue and illness.
You Are What You Eat
To remain healthy, eat foods that help
your body maintain the slightly alkaline
balance in the blood. In general, this means
eating more vegetables and fewer animal
products. To maintain health, the diet
should consist of at least 60 percent
alkaline-forming foods and at most
40 percent acid-forming foods.
Note that a food’s acid- or alkalineforming tendency in the body is unrelated
to the pH of the food. For example, lemons
are 0very acidic. However, after digestion,
they form alkaline products in the body.
Similarly, meat tests alkaline before digestion,
but like nearly all animal products, meat is
classified as acid-forming.
Applying Critical-Thinking Skills
Directions: Answer each question.
1. Infer When you have indigestion, the contents of the stomach can back up into the
esophagus, which does not contain protective mucus. Why does indigestion produce
a burning sensation in the throat?
2. Apply Saliva has a healthy pH between 6.5 and 7.5. How could you use this
information to make sure your body is getting the foods it needs?
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Challenge
What is acid rain?
The picture at the beginning of Lesson 3 shows the effects of acid rain on a statue.
Research the topic of acid rain. Focus on the following questions:
• What is acid rain?
• What causes acid rain?
• Why is it more of a problem today than it was in the past?
• How does acid rain affect health?
• How does acid rain affect plants and animals?
• How do the concentrations of acid rain vary across the country? Across the world?
• What are some ways to reduce the problem of acid rain?
Design an Educational Web Site
Produce an online multimedia presentation for a Web site devoted to explaining
science topics to younger students. Include diagrams or pictures. You might also make up
interactive activities or quizzes on the topic or include music. Try to make the presentation as
interesting as possible to keep the students’ attention.
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Lesson Quiz A
Acid and Base Solutions
Matching
Directions: On the line before each definition, write the letter of the term that matches it correctly. Each term is
used only once.
1. a substance that produces a hydronium ion when
it is dissolved in water
2. a compound that changes color at different pH
values when it reacts with acidic or basic
solutions
A. indicator
B. acid
C. base
3. a substance that produces hydroxide ions when it
is dissolved in water
Multiple Choice
Directions: On the line before each question or statement, write the letter of the correct answer.
4. Which household item contains an acid?
A. vinegar
B. detergent
C. baking soda
5. The chemical formula for a hydronium ion is
A. H 2 O.
B. OH−.
C. H 3 O+.
6. Which equation shows the relationship between hydronium ions and
hydroxide ions in a neutral solution?
A. H 3 O+ > OH−
B. H 3 O+ = [OH−
C. H 3 O+ < [OH−
7. Which is the most accurate way to measure pH?
A. pH meter
B. pH indicator
C. pH testing strip
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Lesson Quiz B
Acid and Base Solutions
Matching
Directions: On the line before each definition, write the letter of the term that matches it correctly. Not all
terms are used.
1. a substance that produces a hydronium ion when
it is dissolved in water
2. a compound that changes color at different pH
values when it reacts with acidic or basic
solutions
3. a substance that produces hydroxide ions when
dissolved in water
4. inverse measure of the concentration of
hydronium ions in a solution
A. indicator
B. pH
C. neutral
D. acid
E. base
Short Answer
Directions: Respond to each statement on the lines provided.
5. Recall several household and food items that are acidic and several that are basic.
6. State the relationship between the number of hydronium ions and hydroxide ions in
a neutral solution. Write the chemical formula for each ion as part of your answer.
7. List two methods that can be used to measure the pH of a solution.