Made bySURESH KUMAR

KV AFS ARJANGARH, NEW DELHI-47

Characteristics Of AcidsAcids are sour in taste.Acids turn blue litmus to red.Acid have no effect on red litmus .

Examples of Acid- Hydrochloric acid, sulphuric acid

Types of Acid

Characteristics of BasesBases are bitter to tasteBases are soapy to touch.Bases turn Red litmus to blue.Bases have no effect on blue litmus.

Examples : Sodium hydroxide, Calcium hydroxide

IndicatorsIndicators- 1).Litmus(obtained from lichen) 2).Turmeric 3).China rose 4).Phenolphthalein

1).LITMUS- It has mauve(purple) colour in distilled water. It turns red in acidic solution and turns blue in basic solution. It is generally available as a strip of red or blue litmus paper.

Indicators(contd…)2).TURMERIC- The natural turmeric which is

used for cooking purpose, can be used as an acid-base indicator. Turmeric turns red in basic solutions.

3).CHINA ROSE- Warm water added to China rose(hibiscus) petals can be used as an indicator. China rose indicator turns acidic solution to dark pink(magenta) and turns basic solution to green.

Indicators(contd…)PHENOLPHTHALEIN-It is an indicator which is colourless in acid and pink in base.

Neutralisation ReactionThe reaction between an acid and a base is known

as neutralisation. Salt and water are produced in this process with the evolution of heat.

Acid + Base = Salt + Water

(Heat is evolved)

Eg - HCl + NaOH = NaCl + H2O

Neutralisation in everyday lifeThe various uses of neutralisation reactions in our

everyday life are:-1). INDIGESTION-Sometimes the amount of HCl in

stomach increases which is called acidity. Milk of magnesia is the base used to cure acidity.

2). ANT STING- It contains formic acid. It is injected when ant bites and the effect can be neutralised by rubbing moist baking soda or calamine lotion.

3). SOIL TREATMENT- Excess of fertilizers make soil acidic which is harmful. Base like quick lime or slaked lime can neutralise the soil.

RECAPTULATIONQ). Which acid is known as the “king of chemicals”?

Q). What is the common name of calcium hydroxide?

Q). What is the colour of base in methyl orange?

Q). Is coffee acidic or basic in nature?

Q). What is the difference between acids and base?

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