Acids bases and salt

1. ACIDS, BASES, AND SA~TcS

2. Acids
An acid is a substance that produces
h dro en ions (H·) when placed in water
- When acids/ ionic compounds are dissolved in water,
the ions split apart from each other (dissociation)

3. Properties of Acids
Most acids...
• Taste sour
• React w/many metals to form H2 gas
• Are corrosive (appears to "eat away" materials
while reacting)
• Have a chemical formula that begi
Zinc Metal + Hydrochloric Acid ➔ ??
Zn <•I + 2 HCI l•ql ➔
Pradlct thct type of ro:ict,on buad on tho raact:intal

4. Common Acids
· Citric Acid
• Found in citrus fruits
· Used as a preservative
· Lactic Acid
• Found in yogurt
• Produced by our muscles when they are overworked
· Acetic Acid (HC2H3O2)
• Vinegar
• Used as a preservative
Carbonic Acid ( H2CO3) or Phosphoric
• Found in soft drinks
· Hydrochloric Acid (HCI)
• Found in our stomachs- aids in food digestion

5. Bases
A base is a substance that produces
h droxide ions (OH-) when placed in water
When bases/ ionic compounds are
dissolved in water, the ions split apart from
each other (dissociation)

6. Properties of Bases
Most bases.. .
• Taste bitter
• Feel slippery
• Are corrosive (appears to "eat away" materials
while reacting)
• Have a chemical formula that ends with OH
/I'
,....·. .
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. , ' ~5••
. · 1'"t , . •
. . :,~ j,1:'J
• . • Ill'• '
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,.. ·. :>,e·,~

7. Common Bases
·-~
1
Ammonia
• Cleaners and fertilizers
• Sodium hydroxide
• Used in soaps and drain cleaners
• Magnesium hydroxide
• An ingredient found in antacids

8. Indicators
Indicators are used to determine if a substance is
an acid or a base
An indicator changes a specific color when in the
presence of an acid or a base
: ,: , ·. - :· : .• ,: indicator made of a special filter paper
that contains dyes extracted from lichens (the crusty
"stuff' that grows in rocks)
litmus turns in an ACID
litmus turns in a BASE
Why do you think it's important to test an
unknown substance with both types of litmus
paper?

9. The pH scale can also help us classify
solutions as acids or bases
pH is a measure of th,e amount of H•
ions in a solution (potential hydrogen)
• The more H'ions, the lower the pH, the
more acidic the solution

10. pH Scale
- - - - - -
I • s
Ml. ~ Ammonia Oritln clHMf
6 7 I 9 10 '' ~
I , -=----=?
lllood plume Milk of
~ i .

11. Complete the following chart by telling whether the pH
represents an acid, base or neutral substance.
Also tell what color each type of litmus paper will turn at
that pH level.
Acid/8aMINeu11'11 Colo. of Blue Uunus Paper Color ol Red Utmue P•J>M
L _
13

12. Strength vs Concentration
When describing acids and bases, strength and
concentration do not mean the same thing!
• Strenath refers to the ability of the acid/base to
dissociate in solution
pH measures this
· Dissociation refers to the abiility of an ionic compound to
break apart into ions
• Concentration refers to the amount of acid/base
dissolved in solution.
An acid or base will have the same pH, regardless of how
concentrated it is
· Just because you add water to dilute ii, it's still going to have the
same amount of H· ions, they'll just be spread out more

13. Stro1
ng/Weak Acids & Bases
When a strong acid/base dissolves in
water, nearly all of the acid/base
molecules will dissociate into ions
3
The greater the ability to dissociate, the
more potential the acid or base has for
being dangerous because there are n1ore
ions available to react
When a weak acid/base dissolves in
water. only a small fraction of the
acid/base molecules dissociate
(dissociate partially)
.:; With less ions in solution, there is less
potential for danger because there are
less ions available to react

14. Strong/Weak Acids Examples
Strong Acids
1. HCI - hydrochloric acid - stomach
acid
2. H1S04 - sulfuric acid - battery acid
3. HN03 - nitric acid
Weak Acids:
1. HC1H30 1 - acetic acid - vinegar
2. H3C6H50 7 -citric acid -citrus fruits

15. Strong/Weak Bases Examples
Strong Bases:
1. NaOH - sodium hydroxide
2. Any alkali or alkaline earth metal with OH·
(i.e. KOH - potassium hydroxide)
Weak Bases:
1. Al(OH), - aluminum hydroxide - often found in
deodorants
2. NH,OH - ammonium hydroxide (ammonia) -used in
many cleaning products

16. Neutralization
Neutralization is a chemical reaction between an
acid and a base that takes place in a water solution
When acids and bases react, the H· ions from the
acid react with the OH· ions from the base to form
HOH (H2O - water!)
The overall pH becomes "neutral"
Many people that suffer from heartburn will take antacids to ease their
symptoms (i.e TUMS). How do you think antacids work?

17. Salts
, The ions that are left behind after the H' and OH·
ions form water, combine to form a salt
• A salt is a compound that forms when the negative ions
from the acid combine with the positive ions from the
base
Acid + Base ➔ Water + Salt
What type of reaction is a neutralization reaction?
Name the salt produced in this neutralization reaction.