Acids, Bases and Salts 17
ACID, BASE AND SALTS
1. Write answers to the
following questions.
(a) Explain the
difference between acids and bases.
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Acids
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Bases
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(1) Acids have sharp
sour taste.
(2) Blue litmus turns
red in acidic solution.
(3) In an acid there is
H group.
(4) 'H' group gives
acidic properties.
(5) Example:
Hydrochloric acid, Sulphuric acid, Acetic acid.
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(1) Bases have sharp
astringent taste.
(2) Red litmus turns
blue in basic solution.
(3) In a base there is
OH group.
(4)'OH' group gives
basic properties.
(5) Example: Sodium
hydroxide, Calcium hydroxide.
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(b) Why does an indicator not affect common
salt?
(1)
Litmus is used to identify acids and bases. If it is added to an acid it turns
red, and if added to a base it turns blue.
(2) Salt is formed after the neutralization reaction of an acid and a base
therefore it is a neutral substance. (2) A neutral substance does not have
acidic or basic properties. (s) Neutral substances do not affect either red or
blue Litmus paper. (4) Therefore an indicator like litmus is not affected by
common salt.
(c) Which substances are formed as a result
of a neutralization reaction?
The chemical reaction that
takes place between acids and bases is called neutralization. (2) It results in
the formation of salt and water.
(d) Explain the
difference between a base and an alkali.
(1) When a base is
dissolved in water it is called alkali. (2) All alkalis are bases but all bases
are not alkalis. (3) Bases are those which in solutions are soapy to touch. (4)
Sodium hydroxide (NaOH) is basic, its solution in water is alkaline.
2. Fill in the blanks.
(a) The main constituent
of an acid is H.
(b) The main constituent
of a base is OH.
(c) Tartaric acid is a weak acid.
(d) To get acidic salts strong acids are used.
3. Match the following.
Group ‘A’ Group ‘B’
(a)
tamarind------- 3. Tartaric acid
(b)
yoghurt -------- 4. Lactic acid
(c)
lemon ----------- 2. Citric acid
(d)
acetic acid ----- 1. vinegar
4. True or false?
(a) Oxides of metals are basic.
-------- TRUE
(b) Common salt is acidic.
------- FALSE (Common salt is neutral)
(c) Salts corrode metals.
------- FALSE (Acids and bases corrodes metals)
(d) Bases are formed by
the neutralization reaction between acids and salts. ------- FALSE (salts are
formed by the neutralization reaction between acids and bases)
(e) Salts are neutral.
-------- FALSE (Not all salts neutral)
5. Find the
odd-man-out.
(a) HN03, H2SO4,
HCl, Na2CO3 ----------
Na2CO3. (Others are acids.)
(b) MgO, CaO, H2O,
Na2O. ---------- H2O.
(Others are oxides of metals.)
(c) NaHCO3,
NaOH, NH4OH, CH3COOH ---------- CH3COOH (Others are basic salts.)
(d) NaCl, C12H22O11,
KCl, CuSO4 ---------- C12H22O11.
(Others are salts.)
(e) HCl, H2S04,
HNO3, CH3COOH ----------
CH3COOH. (Others are strong acids.)
6. Classify the
following substances as acidic, basic and neutral.
HCl, NaCl,
MgO, KCl, CaO, H2SO4, HNO3, H2O, N2CO3.
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