ACIDS, BASES &
SALTS
Ions
 Some
times substances go through a
reaction that breaks off a hydrogen or
even a hydrogen and an Oxygen.
 These
extra Ions (Charged Particles) are
what make up Acids and Bases.
 H2O
-> H+ + OH-
Ions
 Because
the Single Hydrogen no longer
shares that electron is becomes positively
charged.
 He
is now called a Hydrogen Ion.
Ions
 The
Oxygen and Hydrogen now have an
extra electron and become negatively
charged.
 They
are now called a Hydroxide Ion.
Acid
 Any
substance that has extra Hydrogen
Ions is an acid.
 The
more Hydrogen Ions the more acidic.
Basis
 When
a substance has extra hydroxide
ions (OH- ) then it is a base.
 The
more hydroxide ions the more basic.
 (Bases
can also be called Alkaline)
pH Scale
 The
pH scale was created to better
compare the relative concentration of
Hydrogen ions.
 pH
stands for partial Hydrogen.
 The
scale ranges from 0 to 14 and each
step is a multiple of 10. The scale is
logarithmic.
pH
 Example:
 Urine
generally has a pH of 6 where as
water has a pH of 7.
 This
means that Urine has 10 times more
Hydrogen Ions than water.
pH
A
pH of 7 is considered neutral.
 This
means that there as many Hydrogen
ions as there are hydroxide ions.
 They balance each other out.
TERMS
ACIDS are substances that form hydrogen ions (H+(aq))
when dissolved in water eg

BASES are hydroxides that react and neutralize.


In acid solutions there are more H+ ions than
OH- ions.
In alkaline solution there are more OH- ions
than H+ ions.
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Topic 10: ACIDS, BASES &
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Strong or Weak
- Acids or Bases that dissociate completely are Strong
Acids/Bases.

Acids or Bases that dissociate only partially are Weak
Acids/Bases
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Topic 10: ACIDS, BASES &
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Physical Properties of Acids & Bases

ACIDS





Acids taste sour (e.g. vinegar, lemon juice).
Acids are harmful to living cells.
Aqueous solutions of all acids contain hydrogen ions.
Acid turns blue litmus red.
Strong acids are corrosive.

BASES




Alkalis are taste bitter
Strong alkalis are corrosive.
Aqueous solutions of all alkalis contain hydroxide ion.
Alkalis turns red litmus blue.
Soapy touch.

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Topic 10: ACIDS, BASES &
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Neutralization

H+1 + OH-1  HOH

Acid + Base  Water + Salt (double replacement)

Example:

HCl (aq) + NaOH (aq)  HOH (l) + NaCl (aq)

H2SO4 (aq) + KOH (aq)  2 HOH (l) + K2SO4 (aq)
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Topic 10: ACIDS, BASES &
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SALTS
When H+ ion of an acid is replaced by a metal ion, a
salt is produced e.g.
 H2SO4+ 2NaOH====== Na2SO + 2H2O


Here sodium sulphate (Na2SO4) is the salt formed.
Salts are ionic compounds.
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Topic 10: ACIDS, BASES &
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Methods of making Soluble
Salts
1)
ACID + METAL  SALT + HYDROGEN
2)
ACID + BASE  SALT + WATER
3)
ACID + CARBONATE  SALT + WATER +
CARBON
DIOXIDE
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Topic 10: ACIDS, BASES &
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Types of Salts
 Normal
Salts:
 Normal salts are formed when all the
replaceable hydrogen ions in the acid have
been completely replaced by metallic ions.

HCl(aq) + NaOH(aq)  NaCl(aq)

H2SO4(aq)
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+
ZnO(aq)

+ H2O(l)
ZnSO4(aq) + H2O(l)
Topic 10: ACIDS, BASES &
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17
Types of Salts
 Acid
salts:
 Acid salts are formed when replaceable
hydrogen ions in acids are only partially
replaced by a metal.
 H2SO4 + KOH  KHSO4 + H2O
 H3PO4
+ NaOH  NaH2PO4 +
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Topic 10: ACIDS, BASES &
SALTS
H2O
18
Types of Salts
 Basic
Salts:
 Basic salts contain the hydroxide ion, OH-.
They are formed when there is insufficient
supply of acid for the complete neutralization of
the base.
Zn(OH)2 + HCl  Zn(OH)Cl +
H2O
Mg(OH)2 + HNO3  Mg(OH)NO3 + H2O
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Topic 10: ACIDS, BASES &
SALTS
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USES OF SALTS
S.No
.
SALT
USE
1
Ammonium Chloride
In torch batteries
2
Ammonium Nitrate
In fertilizers
3
Calcium Chloride
As drying agent
4
Iron Sulphate
In Iron tablets
5
Magnesium Sulphate
In medicine
6
Potassium Nitrate
In gunpowder etc.
7
Silver Bromide
In photography
8
Sodium Chloride
Making NaOH
9
Sodium Stearate
In making soap.
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Topic 10: ACIDS, BASES &
SALTS
20
THE
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END
Topic 10: ACIDS, BASES &
SALTS
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