2. ACIDSACIDS
AcidsAcids are those substances which are sourare those substances which are sour
in taste, produce burning sensation onin taste, produce burning sensation on
touching and which turn blue litmus to red.touching and which turn blue litmus to red.
Examples – Citric acid, oxalic acid,Examples – Citric acid, oxalic acid,
hydrochloric acid.hydrochloric acid.
Curd, lemon juice, orange juice and vinegarCurd, lemon juice, orange juice and vinegar
taste sour. These substances taste sourtaste sour. These substances taste sour
because they contain acids.because they contain acids.
The chemical nature of such substances isThe chemical nature of such substances is
aa acidicacidic. The word acid comes from the Latin. The word acid comes from the Latin
wordword acereacere which means sour.which means sour.
22
4. 44
NAME OF ACID FOUND IN
Acetic Acid Vinegar
Formic acid Ant’s sting
Citric Acid Citrus foods such as oranges,
lemons etc
Lactic Acid Curd
Oxalic Acid Spinach
Ascorbic Acid (Vit ‘C’) Amla, citrus fuits
Tartaric Acid Tamarid, grapes, unripe
mango etc
5. BASESBASES
Bases are those substances which are bitterBases are those substances which are bitter
in taste, are soapy to touch and which turnin taste, are soapy to touch and which turn
red litmus to blue. Example Sodiumred litmus to blue. Example Sodium
Hydroxide, Potassium hydroxide etc.Hydroxide, Potassium hydroxide etc.
The nature of such substances is said to beThe nature of such substances is said to be
basic.basic.
55
7. 77
NAME OF BASES FOUND IN
Calcium Hydroxide Lime Water
Ammonium
Hydroxide
Window Cleaner
Sodium
Hydroxide/Potassium
Hydroxide
Soap
Magnesium
Hydroxide
Milk of Magnesia
8. INDICATORSINDICATORS
The special substances which are used toThe special substances which are used to
test whether a substance is acidic or basictest whether a substance is acidic or basic
are known as indicatorsare known as indicators
The indicators change colour when added toThe indicators change colour when added to
a solution containing an acidic or a basica solution containing an acidic or a basic
substance.substance.
Some of the naturally occurring indicatorsSome of the naturally occurring indicators
areare turmeric, litmus, china rose petals etc.turmeric, litmus, china rose petals etc.
88
10. NEUTRALISATIONNEUTRALISATION
The reaction between an acid and a base isThe reaction between an acid and a base is
known as neutralization. Salt and water areknown as neutralization. Salt and water are
produced in this process with the evolutionproduced in this process with the evolution
of heat.of heat.
In neutralization reaction heat is alwaysIn neutralization reaction heat is always
produced or evolved.produced or evolved.
In neutralization reaction a new substanceIn neutralization reaction a new substance
is formed. This is called salt. Salt may beis formed. This is called salt. Salt may be
acidic, basic or neutral in nature.acidic, basic or neutral in nature.
1010
11. ACTIVITY TEST WITH DIFFERENTACTIVITY TEST WITH DIFFERENT
INDICATORSINDICATORS
1111
TEST SOLUTION CHINA ROSE
INDICATOR
TURMERIC
INDICATOR
LITMUS SOLUTION
BLUE/RED
HCL (Hydrochloric
Acid)
Red No change Blue to Red
NAoH
Sodium Hydroxide
Green Red Red to Blue
Soap solution Green Red Red to Blue
Baking Powder Green Red Red to Blue
Lemon Juice/
Tomato Juice
Red No Change Blue to Red
Vinegar Red No Change Blue to Red
Sugar No Change No Change No Change
