Class 7 Acid Base and Salts presentation

1. ACIDS, BASES & SALTS
Shivani Dhiman

2. • An acid is a chemical substance
that has a sour taste.
• Many food items such as
lemons, curd, vinegar and
orange taste sour because of the
presence of acid in them.
• Acidic Substances are the
substances that contain acid in
them.
ACIDS

3. EXAMPLES OF ACIDS
• Lemon juice
• Orange juice
• Vinegar
• Curd
• Tamarind
• Amla
• Unripe Mango
• Grapes

5. BASE
(ALKALINE)
Base bitter to taste
Soapy to touch
Bases are found in different substances
such as bleach, ammonia, washing
powder and soap.

6. EXAMPLES OF
BASE
DETERGENT BAKINGSODA DRAIN CLEANER
ANTACID BASE AMMONIA
SOPS(HAND, DISH)
LIME WATER

7. NAME OF BASE
- FOUND IN
Sodium hydroxide - Soaps
Calcium hydroxide - Lime Water
Ammonium hydroxide - Window
cleaners
Magnesium hydroxide - Milk of magnesia

8. NEUTRAL SUBSTANCE
Neutral Substance is any
substance which is neither acidic
nor basic in nature. Examples are
pure water, table salt, sugar
solution etc.

9. INDICATORS
• We cannot taste every object and find its
nature. Therefore, we use indicators.
• An indicator is a substance that can
determine if another substance is acidic or
basic in nature.
• The indicators indicate the presence of an
acid or base in a substance by changing their
colour.

10. EXAMPLES OF
INDICATOR
Litmus (paper/solution)
Turmeric
China rose
Phenolphthalein Indicator

11. NATURAL
INDICATOR
(LITMUS)
Litmus: A natural indicator
It is extracted from lichens. It has a purple
colour in distilled water.
When added to an acidic solution, it turns red
and when added to basic solution it turns
blue.
Generally, it is available as red and blue litmus
paper.

12. LITMUS PAPER

13. TURMERIC
(NATURAL
INDICATOR)
• To use turmeric as an indicator it is generally mixed with
water to form a paste which is then put on blotting paper
and dried to form thin strips of turmeric paper.
• The turmeric paper is then put into the solutions in order
to determine their acidic or basic nature.

14. TURMERIC(NATURAL INDICATOR)

15. CHINA ROSE
China Rose petals are kept in warm water and a coloured solution is
obtained. This coloured solution is used as an indicator to identify the
acidic or basic nature of substances.

16. PHENOLPHTHALEININDICATOR
Phenolphthalein is a synthetic
indicator which is colourless in acid
solution but turns pink to red as the
solution becomes alkaline(basic).

17. NEUTRALISATION
When an acidic solution is mixed
with a basic solution, both the
solutions neutralise the effect of
each other.
the reaction between an acid and a
base is known as neutralisation.
Salt and water are produced in this
process with the evolution of heat.

18. NEUTRALIZATION IN EVERYDAY LIFE
1. Indigestion -
During indigestion, taking milk of magnesia (magnesium hydroxide)
gives us relief as it neutralizes the effect of excess acid produced inside
the stomach.

19. 2. Ant Bite -
The effect of ant sting which is caused by formic acid can be neutralized by
rubbing moist baking soda (basic in nature).
3. Soil Treatment -
Plants do not grow well when the soil is either too acidic or too
basic. When the soil is too acidic, it is treated with bases like quick lime
(calcium oxide) or slaked lime (calcium hydroxide). If the soil is basic,
organic matter is added to it. Organic matter releases acids which
neutralises the basic nature of the soil.

20. 4. Factory wastes -
The wastes of many factories contain acids. If they are allowed to flow in to
the water bodies, the acids will kill fish and other organisms. The factory
wastes are, thererfore, neutralised by adding basic substances.

21. Thank you