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 H2SO4 Potassium hydroxide KOH
– Nitric Acid HNO3 Calcium hydroxide Ca(OH)2
– Acetic Acid CH3 COOH – Ammonium hydroxide NH4OH
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.
11 X – Science
AK
, 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 → ZnCl2 + H2
2HNO3 + Zn → Zn (NO3)2 + H2
H2SO4 + Zn → ZnSO4 + H2
2CH3COOH + Zn → (CH3COO)2 Zn + H2
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 → Na2ZnO2 + H2
Sodium Zincate
Note – Such reactions are not possible with all the metals.
12 X – Science
AK
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 H2SO4 Potassium hydroxide KOH
– Nitric Acid HNO3 Calcium hydroxide Ca(OH)2
– Acetic Acid CH3 COOH – Ammonium hydroxide NH4OH
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.
11 X – Science
AK
, 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 → ZnCl2 + H2
2HNO3 + Zn → Zn (NO3)2 + H2
H2SO4 + Zn → ZnSO4 + H2
2CH3COOH + Zn → (CH3COO)2 Zn + H2
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 → Na2ZnO2 + H2
Sodium Zincate
Note – Such reactions are not possible with all the metals.
12 X – Science
AK
