Lesson 1
Acids and Bases
Focus Question
How can you determine whether a solution is
acidic or basic?
Learning Objective
The students will be able to:
1. Identify the properties and Uses of Acid and
Base
2. Identify acid and base using Litmus paper.
Review Vocabulary
Electrolyte: a compound that breaks apart in
water, forming ions that can conduct electricity
Objective:
U6 M22L1 – Acid and Base
Determine
whether a
solution is
acidic or basic
Keywords
•
•
•
•
•
•
Acid
Base
Litmus paper
pH scale
Hydronium ion----H3O+
Hydroxide ion-----OH-
VOCABULARY
Watch This!
Acids
•
An acid is a substance that produces hydrogen ions (H+) in a water
solution.
•
The H+ ions bind to water molecules to produce hydronium ions: H3O+.
•
Acids are corrosive and can burn your skin.
•
They can react strongly with metals such as zinc to produce hydrogen
gas (H2).
•
Acids cause the sour taste in foods such as limes and pickles.
•
They tend to turn indicators red.
Solutions of Acids
• An acid ionizes in water, producing hydronium ions
when the hydrogen ions from the acid become
attracted to water molecules.
• For example, when hydrogen chloride is added to water,
a hydronium ion and a chloride ion are produced.
Question: is this an example of ionization or dissociation?
Critical Thinking
Should you use a strong acid to clean out
your metal drains? Why or why not?
We shouldn’t use acids to clean out metal
Answer
drains because the
acid can corrode the
metal.
Objective:
Identify Acid and Base
using Litmus paper
and pH scale.
Keywords:
U6 M22L1 – Acid and Base
Learning
Check
ACIDS
Acid
Base
Sour
Bitter
Hydronium ion---H+
Hydroxyl ion----OH-
• Taste sour
• Are corrosive
• Produce hydrogen gas when reacting
with metals.
• Produce hydronium ions H3O+
Acids
Some Common Acids and Their Uses
Name, Formula
Use
Other Information
Acetic acid (CH3COOH)
food preservation,
commercial organic
synthesis
vinegar (about 5% acetic acid)
Ascorbic acid (H2C6H6O6)
antioxidant, vitamin
Vitamin C; occurs naturally in
some foods and is added to
others
Carbonic acid (H2CO3)
carbonated drinks
involved in cave formation and
acid rain
Hydrochloric acid (HCl)
cleans steel in a process
called pickling
Gastric juice in the stomach is
a solution of HCl and water.
Sulfuric acid (H2SO4)
car batteries; to
manufacture fertilizers
and other chemicals
Dehydrating agent that
extracts water from air.
Watch This!
Bases
•
Most bases contain an OH–, called a hydroxide ion, in their chemical
formula.
•
A base is a substance that produces hydroxide ions when it is dissolved
in water.
•
Also, a base is any substance that accepts H+ from acids.
•
In their pure state, many bases are crystalline solids. This is because
they are ionic compounds like salts.
•
In solution, bases feel slippery and have a bitter taste.
•
They are corrosive and can burn skin.
•
Bases tend to turn indicators blue/purple.
Solutions of Bases
• Most bases are ionic compounds, made up of positive
metal ions and hydroxide ions. In water, such bases
dissociate, forming positive metal ions and hydroxide
ions.
• For example, when sodium hydroxide dissolves in water,
a sodium ion and a hydroxide ion are produced.
Solutions of Acids and Bases
•
Some bases are neutral compounds that accept H+ ions from
acids, or even from water.
•
These types of bases can ionize other molecules to produce
hydroxide ions in solution, even though they do not have an OH
group.
•
For example, ammonia, NH3, reacts with water to produce
hydroxide ions in solution. In this case, water acts as an acid.
Common Bases
•
Sodium bicarbonate, NaHCO3 is a base used in baking.
•
Amines (compounds with an – NH2 group) are found in many foods.
•
Soaps and cleaners are generally bases, although limescale remover for
your bathroom will contain a strong acid.
•
Sodium hydroxide (NaOH) is used in the paper industry to separate the
cellulose fibers needed for paper from the wood pulp.
•
Aluminium hydroxide is used
in water treatment plants.
It’s sticky surface collects impurities,
making them easier to remove.
Bases
Some Common Bases and Their Uses
Name, Formula
Use
Other Information
Aluminium hydroxide
(Al(OH)3)
color-fast fabrics, antacid,
water purification
sticky gel that collects suspended
clay and dirt particles on its
surface
Calcium hydroxide (Ca(OH)2)
to make leather, mortar and a.k.a slaked lime
plaster; to lessen soil acidity
Magnesium hydroxide
(Mg(OH)2)
laxative, antacid
called milk of magnesia when it
is mixed with water
Ammonia (NH3)
cleaners, fertilizer; to make
rayon and nylon
irritating odor that is damaging
to nasal passages and lungs
U6 M22L1 – Acid and Bases
Keywords:
Learning
Check
BASES
Acid
Base
1. Taste bitter
Sour
Bitter
2. Soapy to touch
Hydronium ion---H3O+
Hydroxyl ion----OH-
3.Produce Hydroxide ions OH-
Critical Thinking
What ions do acids produce?
What ions do bases produce?
Do you notice anything interesting about these ions?
H+
Answer
-OH
If you add them together, you get H2O
Objective:
Identify Acid and Base
using Litmus paper and
pH scale.
U6 M22L1 – Acid and Bases
Brain storming
Keywords:
Acid
Base
If you have two beakers:
1. With an acid
2. With a base
Indicator
Litmus paper
pH scale
How will you identify
which beaker has acid and
which has base?
Objective:
Identify Acid and Base
using Litmus paper and
pH scale.
Keywords:
U6 M22L1 – Acid and Bases
Indicators: Litmus paper
Acid
Base
Litmus paper
pH scale
We need something
which can help us to identify
between acid and base.
We call them as indicators
One of such indicator is Litmus paper
Understand
Objective:
Identify Acid and Base
using Litmus paper
and pH scale.
U6 M22L1 – Acid and Bases
Understand
Keywords:
Acid
Base
Litmus paper
pH scale
Acid
Base
Objective:
Identify Acid and Base
using Litmus paper
and pH scale.
Word wall:
Acid
Base
Litmus paper
pH scale
U6 M22L1 – Acid and Bases
Understand
and
Apply
Identify the Solution – Acid or base
Quiz
1. Which is NOT characteristic of an acid?
A
tastes sour
B
feels slippery
C
turns blue litmus red
D
a source of H+ ions
Quiz
2. Which is the term for H3O+?
A
hydroxide ion
C
trihydrogen oxide ion
B
hydronium ion
D
hydrogen ion
Quiz
3. Which is NOT characteristic of bases?
A
produce OH– in water
B
corrosive and damaging to skin
C
turn blue litmus red
D
bitter-tasting
Quiz
4. Which is an example of a base?
A
HCl
B
HNO3
C
NH3
D
H3PO4
Quiz
5. Unlike acids, bases made up of positive metal ions and
hydroxide ions _______ in water.
A
dissociate
C
react
B
ionize
D
crystallize
Lesson Summary
• Acids are sour tasting and corrosive;
they make the blue litmus paper turn
red
• Bases exist as crystals in the solid
state, they are slippery, have a bitter
taste, are corrosive and make the red
litmus paper turn blue
• Because water is polar, acids and
bases can dissolve in it and produce
ions
Plenary
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707f73/g8-acids-and-bases