Grade 7 Science Lessons

1. Acids, Bases, and Salts

2. Lesson Outline:
 Acids vs. Bases Comparison
 Neutralization reaction
 pH scale
 Salts

3. Acids, bases, and salts
are evident in the quality
of environment, food
and everyday living
Compounds may be
classified into acids,
bases, or salts.

4. Are substances whose
colors are affected by acids
and bases.
Indicators

6. Acids vs. Bases
When dissolved in water,
acids:
1. Conduct electricity
2. Change blue litmus to red
3. Have a sour taste
4. React with bases to
neutralize their properties
5. Contains H+ ions at the
beginning of their formula
Ex. HCl
When dissolved in water, bases:
1. Conduct electricity
2. Change red litmus to blue
3. Have a slippery feeling and bitter
taste
4. React with acids to
neutralize their properties
5. Contains hydroxide OH- ions the
end of their formula
Ex. NaOH

7. Acids have H+ ions at the beginning of
their formula
Examples:
 H2CO3
 HCOOH
 Exceptions are the hydrocarbons (they
have C and H in the beginning and a
carboxylic acid at the ending [HCOOH])
like CH3COOH, CH3CHOHHCOOH
Bases have hydroxide
OH- ions the end of their
formula
Examples:
 Ca(OH)2
 Mg(OH)2
carboxylic acid
Hydrocarbon methane
Acids vs. Bases

8. Most acids have a suffix
–ic attached
Examples:
 Sulfuric acid (H2SO4)
 Nitric acid (HNO₃)
 Acetic acid (vinegar)
(CH₃COOH)
Bases have hydroxide attached at
the end
Examples:
 Sodium hydroxide (NaOH)
 Calcium hydroxide (Ca(OH)₂)
 Magnesium hydroxide (Mg(OH)2)
Acids vs. Bases

9. Acids are
important even
in your body.
Acids in the body

10. Acid can be
found in your
teeth. They are
produced by
bacteria. So
always brush
your teeth.
Acids in the body

11. Acid can also
be found in
your stomach.
Hydrochloric
acid helps
digest food.
Acids in the body

12. Hydrochloric
acid in your
stomach is ten
times stronger
than carbonic
acid found in
soft drinks.
Acids in the body

13. Acids, in the form
of sweat helps also
regulate body
temperature. The
bad odor is caused
by the bacteria.
Acids in the body

14. Acids are also
important in the
industries.
Acids in the industry

15. Sulfuric acid
Acids in the industry
 manufacture of plastics,
detergents, batteries, and
metals

16. Nitric acid
Acids in the industry
 manufacture of
explosives, rubber, dyes,
and pharmaceuticals

17. Phosphoric acid
Acids in the industry
 manufacture of fertilizers,
animal feeds, detergents, and
ceramics

18. Acetic acid
Acids in the industry
 manufacture of plastics,
detergents, batteries, and
metals

19. Binary or simple acids – contains two different
elements, hydrogen and a nonmetal (ex. HCl)
Oxyacids – contains oxygen (ex. HNO3)
Kinds of Acids

20. Common Acids
• H2SO4- sulfuric acid - car batteries
• HNO3
– nitric acid - explosives
• HC2H3O2- acetic acid - vinegar
• H3PO4- phosphoric acid -flavorings
• H2CO3-carbonic acid – sodas

21. Some Common Acids
Ascorbic acid – citrus fruits
Formic acid – red ants
Lactic acid – sour milk

23. What is a BASE?
• Called alkaline substances
• Have bitter taste
• Feels slippery
• Dissolves fats and oils
• Changes the color of substance, red litmus turns
blue
• Neutralizes acids forming water and salts

24. Common Bases
•NaOH- sodium hydroxide (LYE) soaps, drain cleaner
•Mg (OH)2 - magnesium hydroxide-antacids
•Al(OH)3-aluminum hydroxide-antacids, deodorants
•NH4OH-ammonium hydroxide- “ammonia”

25. What do you think will happen
when an acid and a base are
mixed?

26. Process of mixing an
acid and a base to
produce a neutral
solution.
They combine to form
1. Water
2. Salts
NEUTRALIZATION

27. pH - a measure of H+
concentration in a
solution
Acid < 7
Base > 7
Neutral (pure H2O) = 7
pH SCALE

29. What is a SALT?
•A salt is a neutral substance produced from the reaction of an
acid and a base.
•Composed of the negative ion of an acid and the positive ion
of a base.
•One of the products of a Neutralization Reaction
Examples: KCl, MgSO4, Na3PO4, NaCl (salt), Potash (K2CO3),
Chalk (CaCO3)

30. Will the pH increase or decrease if NaCl
(table salt) is added to pure water (H2O)?
NaCl + H2O →
Question:

31. Nothing will happen. Remember that salt
added to water are products of a
neutralization reaction.
NaCl + H2O → NaOH + HCl
Answer:
base + acid = water and salt

32. Thank You Lirians!