NCERT Notes, Chapter 2: Acids, Bases & Salts, Class 10 (Science) PDF Download

 Page 1


AK
11 X – Science
CHAPTER – 2
ACIDS, BASES AND SALTS
q
Acids Bases
– Sour in taste – Bitter in taste
– Change the blue litmus to red – Change red litmus to blue
– eg. HydrochloricAcid HCl eg. Sodium hydroxide NaOH
– SulphuricAcid H
2
SO
4
Potassium hydroxide KOH
– NitricAcid HNO
3
Calcium hydroxide Ca(OH)
2
– AceticAcid CH
3
COOH – Ammonium hydroxide NH
4
OH
q Some Naturally occuring acids
Vinegar – Acetic Acid
Orange – Citric Acid
Lemon – Citric Acid
Tamarind – Tartaric Acid
Tomato – Oxalic Acid
Sour milk (Curd) – Lactic Acid
Ant and Nettle sting – Methanoic Acid
q Acid – Base Indicators – Indicate the presence of an acid or base in a
solution.
q Litmus solution – It is a natural indicator. It is a purple day extracted from
Lichens. Other examples are Red Cabbage and coloured petals of Petunia
and turmeric.
q Olfactory indicators – Show odour changes in acidic or basic media. eg.
onion and clove.
Page 2


AK
11 X – Science
CHAPTER – 2
ACIDS, BASES AND SALTS
q
Acids Bases
– Sour in taste – Bitter in taste
– Change the blue litmus to red – Change red litmus to blue
– eg. HydrochloricAcid HCl eg. Sodium hydroxide NaOH
– SulphuricAcid H
2
SO
4
Potassium hydroxide KOH
– NitricAcid HNO
3
Calcium hydroxide Ca(OH)
2
– AceticAcid CH
3
COOH – Ammonium hydroxide NH
4
OH
q Some Naturally occuring acids
Vinegar – Acetic Acid
Orange – Citric Acid
Lemon – Citric Acid
Tamarind – Tartaric Acid
Tomato – Oxalic Acid
Sour milk (Curd) – Lactic Acid
Ant and Nettle sting – Methanoic Acid
q Acid – Base Indicators – Indicate the presence of an acid or base in a
solution.
q Litmus solution – It is a natural indicator. It is a purple day extracted from
Lichens. Other examples are Red Cabbage and coloured petals of Petunia
and turmeric.
q Olfactory indicators – Show odour changes in acidic or basic media. eg.
onion and clove.
AK
12 X – Science
q Acid – Base Indicators
S. No. Name of the Colour Change Colour Change
Indicator with Acid with Base
A. Blue litmus solution To red No change
B. Red litmus solution No change To blue
C. Turmeric No change To red
D. Methyl orange To red To yellow
E. Phenolphthalein (colourless) No change To pink
q Dilute Acid : Contains only a small amounts of acid and a large amount of
water.
q Concentrated Acid : A concentrated acid contains a large amount of acid and
a small amount of water.
q Chemical Properties of Acids and Bases
Acid + Metal
-- ?
Salt + Hydrogen
(Refer activity 2.3 on page No. 19 of NCERT Book)
2HCl + Zn
-- ?
ZnCl
2
+ H
2
2HNO
3
+ Zn
-- ?
Zn (NO
3
)
2
+ H
2
H
2
SO
4
+ Zn
-- ?
ZnSO
4
+ H
2
2CH
3
COOH + Zn
-- ?
(CH
3
COO)
2
Zn + H
2
q Pop test : When a buring candle is brought near a test tube containing
hydrogen gas it burns with a ‘Pop’ sound. This test is conducted for examining
the presence of hydrogen gas.
q Base + Metal
-- ?
Salt + Hydrogen
NaOH + Zn
-- ?
Na
2
ZnO
2
+ H
2
Sodium Zincate
Note – Such reactions are not possible with all the metals.
Page 3


AK
11 X – Science
CHAPTER – 2
ACIDS, BASES AND SALTS
q
Acids Bases
– Sour in taste – Bitter in taste
– Change the blue litmus to red – Change red litmus to blue
– eg. HydrochloricAcid HCl eg. Sodium hydroxide NaOH
– SulphuricAcid H
2
SO
4
Potassium hydroxide KOH
– NitricAcid HNO
3
Calcium hydroxide Ca(OH)
2
– AceticAcid CH
3
COOH – Ammonium hydroxide NH
4
OH
q Some Naturally occuring acids
Vinegar – Acetic Acid
Orange – Citric Acid
Lemon – Citric Acid
Tamarind – Tartaric Acid
Tomato – Oxalic Acid
Sour milk (Curd) – Lactic Acid
Ant and Nettle sting – Methanoic Acid
q Acid – Base Indicators – Indicate the presence of an acid or base in a
solution.
q Litmus solution – It is a natural indicator. It is a purple day extracted from
Lichens. Other examples are Red Cabbage and coloured petals of Petunia
and turmeric.
q Olfactory indicators – Show odour changes in acidic or basic media. eg.
onion and clove.
AK
12 X – Science
q Acid – Base Indicators
S. No. Name of the Colour Change Colour Change
Indicator with Acid with Base
A. Blue litmus solution To red No change
B. Red litmus solution No change To blue
C. Turmeric No change To red
D. Methyl orange To red To yellow
E. Phenolphthalein (colourless) No change To pink
q Dilute Acid : Contains only a small amounts of acid and a large amount of
water.
q Concentrated Acid : A concentrated acid contains a large amount of acid and
a small amount of water.
q Chemical Properties of Acids and Bases
Acid + Metal
-- ?
Salt + Hydrogen
(Refer activity 2.3 on page No. 19 of NCERT Book)
2HCl + Zn
-- ?
ZnCl
2
+ H
2
2HNO
3
+ Zn
-- ?
Zn (NO
3
)
2
+ H
2
H
2
SO
4
+ Zn
-- ?
ZnSO
4
+ H
2
2CH
3
COOH + Zn
-- ?
(CH
3
COO)
2
Zn + H
2
q Pop test : When a buring candle is brought near a test tube containing
hydrogen gas it burns with a ‘Pop’ sound. This test is conducted for examining
the presence of hydrogen gas.
q Base + Metal
-- ?
Salt + Hydrogen
NaOH + Zn
-- ?
Na
2
ZnO
2
+ H
2
Sodium Zincate
Note – Such reactions are not possible with all the metals.
AK
13 X – Science
q Action of Acids with metal Carbonates and metal bicarbonates
Metal Carbonate + Acid
-- ?
Salt + Carbondioxide + Water
Na
2
CO
3
(s)
+ 2HCl
(aq)
-- ?
2NaCl
(aq)
+ H
2
O(l) + CO
2(g)
Metal bicarbonate + Acid
-- ?
Salt + Carbondioxide + Water
NaHCO
3
+ HCl
-- ?
NaCl + CO
2
+ H
2
O
q Lime water Test : On passing the CO
2
gas evolved through lime water,
Ca(OH)
2
(aq) + CO
2(g)
-- ?
CaCO
3(s)
+ H
2
O(l)
Lime water White precipitate
On passing excess CO
2
the following reaction takes place
CaCO
3(s)
+ H
2
O
(l)
+ CO
2(g)
-- ?
Ca(HCO
3
)
2
aq
Soluble in water
q Neutralisation Reactions
Base + Acid
-- ?
Salt + Water
NaOH
(aq)
+ HCl
(aq)
-- ?
NaCl
(aq)
+ H
2
O(l)
Neutralisation reacton takes place when the effect of a base is nullified by
an acid and vice versa to give salt and water.
q Reactions of metal oxides with acids
Metal Oxide + Acid
-- ?
Salt + Water
CuO + HCl
-- ?
CuCl
2
+ H
2
O
Copperoxide Hydrochloric Copper + Water
acid chloride
Note : Appearance of blue green colour of the solution because of formation
of CuCl
2
.
Metallic oxides are said to be basic oxides because they give salt and water
on reacting with acids.
q Reaction of Non Metallic Oxide with Base
Non metallic oxide + Base
-- ?
Salt + Water
Ca(OH)
2
+ CO
2
-- ?
CaCO
3
+ H
2
O
Page 4


AK
11 X – Science
CHAPTER – 2
ACIDS, BASES AND SALTS
q
Acids Bases
– Sour in taste – Bitter in taste
– Change the blue litmus to red – Change red litmus to blue
– eg. HydrochloricAcid HCl eg. Sodium hydroxide NaOH
– SulphuricAcid H
2
SO
4
Potassium hydroxide KOH
– NitricAcid HNO
3
Calcium hydroxide Ca(OH)
2
– AceticAcid CH
3
COOH – Ammonium hydroxide NH
4
OH
q Some Naturally occuring acids
Vinegar – Acetic Acid
Orange – Citric Acid
Lemon – Citric Acid
Tamarind – Tartaric Acid
Tomato – Oxalic Acid
Sour milk (Curd) – Lactic Acid
Ant and Nettle sting – Methanoic Acid
q Acid – Base Indicators – Indicate the presence of an acid or base in a
solution.
q Litmus solution – It is a natural indicator. It is a purple day extracted from
Lichens. Other examples are Red Cabbage and coloured petals of Petunia
and turmeric.
q Olfactory indicators – Show odour changes in acidic or basic media. eg.
onion and clove.
AK
12 X – Science
q Acid – Base Indicators
S. No. Name of the Colour Change Colour Change
Indicator with Acid with Base
A. Blue litmus solution To red No change
B. Red litmus solution No change To blue
C. Turmeric No change To red
D. Methyl orange To red To yellow
E. Phenolphthalein (colourless) No change To pink
q Dilute Acid : Contains only a small amounts of acid and a large amount of
water.
q Concentrated Acid : A concentrated acid contains a large amount of acid and
a small amount of water.
q Chemical Properties of Acids and Bases
Acid + Metal
-- ?
Salt + Hydrogen
(Refer activity 2.3 on page No. 19 of NCERT Book)
2HCl + Zn
-- ?
ZnCl
2
+ H
2
2HNO
3
+ Zn
-- ?
Zn (NO
3
)
2
+ H
2
H
2
SO
4
+ Zn
-- ?
ZnSO
4
+ H
2
2CH
3
COOH + Zn
-- ?
(CH
3
COO)
2
Zn + H
2
q Pop test : When a buring candle is brought near a test tube containing
hydrogen gas it burns with a ‘Pop’ sound. This test is conducted for examining
the presence of hydrogen gas.
q Base + Metal
-- ?
Salt + Hydrogen
NaOH + Zn
-- ?
Na
2
ZnO
2
+ H
2
Sodium Zincate
Note – Such reactions are not possible with all the metals.
AK
13 X – Science
q Action of Acids with metal Carbonates and metal bicarbonates
Metal Carbonate + Acid
-- ?
Salt + Carbondioxide + Water
Na
2
CO
3
(s)
+ 2HCl
(aq)
-- ?
2NaCl
(aq)
+ H
2
O(l) + CO
2(g)
Metal bicarbonate + Acid
-- ?
Salt + Carbondioxide + Water
NaHCO
3
+ HCl
-- ?
NaCl + CO
2
+ H
2
O
q Lime water Test : On passing the CO
2
gas evolved through lime water,
Ca(OH)
2
(aq) + CO
2(g)
-- ?
CaCO
3(s)
+ H
2
O(l)
Lime water White precipitate
On passing excess CO
2
the following reaction takes place
CaCO
3(s)
+ H
2
O
(l)
+ CO
2(g)
-- ?
Ca(HCO
3
)
2
aq
Soluble in water
q Neutralisation Reactions
Base + Acid
-- ?
Salt + Water
NaOH
(aq)
+ HCl
(aq)
-- ?
NaCl
(aq)
+ H
2
O(l)
Neutralisation reacton takes place when the effect of a base is nullified by
an acid and vice versa to give salt and water.
q Reactions of metal oxides with acids
Metal Oxide + Acid
-- ?
Salt + Water
CuO + HCl
-- ?
CuCl
2
+ H
2
O
Copperoxide Hydrochloric Copper + Water
acid chloride
Note : Appearance of blue green colour of the solution because of formation
of CuCl
2
.
Metallic oxides are said to be basic oxides because they give salt and water
on reacting with acids.
q Reaction of Non Metallic Oxide with Base
Non metallic oxide + Base
-- ?
Salt + Water
Ca(OH)
2
+ CO
2
-- ?
CaCO
3
+ H
2
O
AK
14 X – Science
Note : Non Metallic oxides are said to be acidic in nature because on reacting
with a base they produce Salt and Water.
q All acidic solutions conduct electricity
Refer activity 2.3 on page 22 of NCERT Book
– Glowing of bulb indicates that there is a flow of electric current through the
solution.
q Acids or bases in a Water Solution
Acids produce H
+
ions in the presence of water
HCl + H
2
O
-- ?
H
3
O
+
+ Cl
–
H
3
O
+
– Hydronium ion.
– H
+
ion cannot exist alone. It exists as H
+
(aq) or (H
3
O
+
) hydronium ion.
H
+
+ H
2
O
-- ?
H
3
O
+
– Bases provide (OH
–
) ions in the presence of water
NaOH
(s) --- - ?
2
H O
Na
+
(aq)
+ OH
–
(aq)
KOH
(s) --- - ?
2
H O
K
+
(aq)
+ OH
–
(aq)
Mg(OH)
2(s) --- - ?
2
H O
Mg
2+
(aq) + 2OH
–
(aq)
q Alkalis
All bases donot dissolve in water. An alkali is a base that dissolves in water.
Common alkalis are
NaOH Sodium hydroxide
KOH Potassium hydroxide
Ca(OH)
2
Calcium hydroxide
NH
4
OH : Ammonium hydroxide
Note : All alkalis are bases but all bases are not alkalis.
q Precaution must be taken while mixing acid or base with water. The acid must
always be added to water with constant stirring as it is highly exothermic
reaction.
Page 5


AK
11 X – Science
CHAPTER – 2
ACIDS, BASES AND SALTS
q
Acids Bases
– Sour in taste – Bitter in taste
– Change the blue litmus to red – Change red litmus to blue
– eg. HydrochloricAcid HCl eg. Sodium hydroxide NaOH
– SulphuricAcid H
2
SO
4
Potassium hydroxide KOH
– NitricAcid HNO
3
Calcium hydroxide Ca(OH)
2
– AceticAcid CH
3
COOH – Ammonium hydroxide NH
4
OH
q Some Naturally occuring acids
Vinegar – Acetic Acid
Orange – Citric Acid
Lemon – Citric Acid
Tamarind – Tartaric Acid
Tomato – Oxalic Acid
Sour milk (Curd) – Lactic Acid
Ant and Nettle sting – Methanoic Acid
q Acid – Base Indicators – Indicate the presence of an acid or base in a
solution.
q Litmus solution – It is a natural indicator. It is a purple day extracted from
Lichens. Other examples are Red Cabbage and coloured petals of Petunia
and turmeric.
q Olfactory indicators – Show odour changes in acidic or basic media. eg.
onion and clove.
AK
12 X – Science
q Acid – Base Indicators
S. No. Name of the Colour Change Colour Change
Indicator with Acid with Base
A. Blue litmus solution To red No change
B. Red litmus solution No change To blue
C. Turmeric No change To red
D. Methyl orange To red To yellow
E. Phenolphthalein (colourless) No change To pink
q Dilute Acid : Contains only a small amounts of acid and a large amount of
water.
q Concentrated Acid : A concentrated acid contains a large amount of acid and
a small amount of water.
q Chemical Properties of Acids and Bases
Acid + Metal
-- ?
Salt + Hydrogen
(Refer activity 2.3 on page No. 19 of NCERT Book)
2HCl + Zn
-- ?
ZnCl
2
+ H
2
2HNO
3
+ Zn
-- ?
Zn (NO
3
)
2
+ H
2
H
2
SO
4
+ Zn
-- ?
ZnSO
4
+ H
2
2CH
3
COOH + Zn
-- ?
(CH
3
COO)
2
Zn + H
2
q Pop test : When a buring candle is brought near a test tube containing
hydrogen gas it burns with a ‘Pop’ sound. This test is conducted for examining
the presence of hydrogen gas.
q Base + Metal
-- ?
Salt + Hydrogen
NaOH + Zn
-- ?
Na
2
ZnO
2
+ H
2
Sodium Zincate
Note – Such reactions are not possible with all the metals.
AK
13 X – Science
q Action of Acids with metal Carbonates and metal bicarbonates
Metal Carbonate + Acid
-- ?
Salt + Carbondioxide + Water
Na
2
CO
3
(s)
+ 2HCl
(aq)
-- ?
2NaCl
(aq)
+ H
2
O(l) + CO
2(g)
Metal bicarbonate + Acid
-- ?
Salt + Carbondioxide + Water
NaHCO
3
+ HCl
-- ?
NaCl + CO
2
+ H
2
O
q Lime water Test : On passing the CO
2
gas evolved through lime water,
Ca(OH)
2
(aq) + CO
2(g)
-- ?
CaCO
3(s)
+ H
2
O(l)
Lime water White precipitate
On passing excess CO
2
the following reaction takes place
CaCO
3(s)
+ H
2
O
(l)
+ CO
2(g)
-- ?
Ca(HCO
3
)
2
aq
Soluble in water
q Neutralisation Reactions
Base + Acid
-- ?
Salt + Water
NaOH
(aq)
+ HCl
(aq)
-- ?
NaCl
(aq)
+ H
2
O(l)
Neutralisation reacton takes place when the effect of a base is nullified by
an acid and vice versa to give salt and water.
q Reactions of metal oxides with acids
Metal Oxide + Acid
-- ?
Salt + Water
CuO + HCl
-- ?
CuCl
2
+ H
2
O
Copperoxide Hydrochloric Copper + Water
acid chloride
Note : Appearance of blue green colour of the solution because of formation
of CuCl
2
.
Metallic oxides are said to be basic oxides because they give salt and water
on reacting with acids.
q Reaction of Non Metallic Oxide with Base
Non metallic oxide + Base
-- ?
Salt + Water
Ca(OH)
2
+ CO
2
-- ?
CaCO
3
+ H
2
O
AK
14 X – Science
Note : Non Metallic oxides are said to be acidic in nature because on reacting
with a base they produce Salt and Water.
q All acidic solutions conduct electricity
Refer activity 2.3 on page 22 of NCERT Book
– Glowing of bulb indicates that there is a flow of electric current through the
solution.
q Acids or bases in a Water Solution
Acids produce H
+
ions in the presence of water
HCl + H
2
O
-- ?
H
3
O
+
+ Cl
–
H
3
O
+
– Hydronium ion.
– H
+
ion cannot exist alone. It exists as H
+
(aq) or (H
3
O
+
) hydronium ion.
H
+
+ H
2
O
-- ?
H
3
O
+
– Bases provide (OH
–
) ions in the presence of water
NaOH
(s) --- - ?
2
H O
Na
+
(aq)
+ OH
–
(aq)
KOH
(s) --- - ?
2
H O
K
+
(aq)
+ OH
–
(aq)
Mg(OH)
2(s) --- - ?
2
H O
Mg
2+
(aq) + 2OH
–
(aq)
q Alkalis
All bases donot dissolve in water. An alkali is a base that dissolves in water.
Common alkalis are
NaOH Sodium hydroxide
KOH Potassium hydroxide
Ca(OH)
2
Calcium hydroxide
NH
4
OH : Ammonium hydroxide
Note : All alkalis are bases but all bases are not alkalis.
q Precaution must be taken while mixing acid or base with water. The acid must
always be added to water with constant stirring as it is highly exothermic
reaction.
AK
15 X – Science
When an acid or a base is mixed with water they become dilute. This results
in the decrease in the concentration of H
3
O+ or OH
–
per unit volume in acids
and bases respectively.
q Strength of an Acid or Base
Strength of acids and bases depends on the no. of H
+
ions and OH
–
ions
produced respectively.
With the help of a universal indicator we can find the strength of an acid or
base. This indicator is called PH scale.
pH = Potenz in German means power.
This scale measures from 0 (very acidic) to 14 (very alkaline) 7 Neutral
(water in Neutral).
pH paper : Is a paper which is used for measuring PH.
V ariation of PH
S. PH Colour of the Nature of H
+
ion O H
–
i o n
No. Value pH Paper Solution Conc. Conc.
1. 0 Dark red Highly acidic very high very low
2. 4 Orange or yellow Acidic high low
3. 7: Green Neutral Equal Equal
4. 10 Bluish green or blue Alkaline low high
5. 14 Dark blue or voilet highly basic very low very high
– strong Acids give rise to more H
+
ions.
eg. HCl, H
2
SO
4
and HNO
3
.
– Weak Acids give rise to less H
+
ions
eg. CH
3
COOH, H
2
CO
3
(Carbonic acid)
– Strong Bases – Strong bases give rise to more OH
–
ions.
eg. NaOH, KOH, Ca(OH)
2
– Weak Bases : give rise to less OH
–
ions.
eg. NH
4
OH