Class 7 Chapter 5 Science Acids, Bases and Salts Notes (NCERT) To make the chapter easier. I hope it helps you.

1. 1) Substances which are sour-> Acid, Substances which are
bitter-> Base, Substances which are neither sour nor
bitter-> Neutral
2) Substances which are used to test whether a substance is
acid or base-> Indicator. Indicators change their colour
when added to a substance with an acidic or basic nature-
>
i) Litmus-> Obtained from lichens, Most commonly
used, Has a mauve(purple) colour in distilled water,
Turns into blue in base and red in acid, Available in
paper form-> Blue litmus paper, Red litmus paper.
Acid Base Neutral
Tastes-> Sour Bitter(except
Coffee)
Neither
sour nor
bitter
Feeling-> Non-soapy Soapy Can be
Non-soapy
and soapy
Contains-> H+
(Hydrogen)
ions)
OH-
(Hydroxide
ions)
No specific
ions
Turns Litmus-> Red or Blue to
Red
Red or Blue to
Blue
No change
Turns Turmeric to-> Yellow Reddish-
Brown
No change
Turns China Rose to-> Dark
Pink(Magenta)
Green No change
Turns Phenolphthalein to -> Colourless Pink No change
Turns Methyl Orange to-> Red Yellow No change
Nature-> Acidic Basic Neutral

2. ii) Turmeric-> Used as a spice, Turns red in base, To
detect acid->use the turmeric used to test base. If
turns back to yellow, It is an acid.
iii)China Rose(Gudhal)-> Turns Magenta in Acid, Turns
Green in base.
3) Acid Rain-> Rain containing excess of acids. It becomes
acidic as pollutants like CO2(Carbon dioxide), NO2-
(Nitrogen Dioxide), SO2(Sulphur dioxide) dissolve in rain
to form H2CO3(Carbonic acid), HNO3(Nitric Acid),
H2SO4(Sulphuric acid). It causes damage to buildings,
historical monuments, plants and animals.
4) The reaction between an acid and a base which forms salt,
water and evolved heat is known as neutralization. In this
process, the acidic and basic of both solutions get
destroyed. Acid+Base Salt+Water+Evolved heat. For
eg.-> HClHydrochloric Acid+NaOHSodium Hydroxide NaClSalt+
H2OWater.
5) Neutralisation in our life->
a) Indigestion-> Stomach uses HCl(Hydrochloric Acid) to
kill microbes in our food. When HCl is released in
excess, it causes indigestion. To relieve pain, we use
antacids (Substances which are used to neutralize the
effect of acid) to neutralize the acid. For eg-> Milk of
Magnesia which contains Mg(OH)2 (Magnesium
Hydroxide).
b) Ant sting-> When ant stings, It releases Formic
Acid(CHOOH). To relieve irritation, we use Moist Baking
Soda(NaHCO3) or calamine solution which contains
ZnCO3(Zinc Carbonate).

3. c) Soil Treatment-> Chemical fertilisers make soil acidic.
We treat the soil with CaO2(Calcium oxide or Quick
Lime) or Ca(OH)2(Calcium Hydroxide or Slaked Lime). If
the soil is too basic, we use compost as it releases acid.
d) Factory wastes-> Factory wastes are to be treated
before being released into water bodies as it may have
acids which could kill fish. Thus, We use bases to
prevent this.
6) Common Acids and bases->
Name of Acid Found in
Acetic Acid Vinegar
Ascorbic Acid (Vitamin
C)
Citrus Fruits, Amla
Citric Acid Citrus Fruits
Formic Acid Ant’s Sting
Lactic Acid Curd
Oxalic Acid Spinach
Tartaric Acid Tamarind, Unripe Mangoes,
Grapes
Name of Base Found in
Ammonium Hydroxide Window cleaner
Calcium Hydroxide Lime Water
Magnesium Hydroxide Milk of Magnesia
Sodium Hydroxide and
Potassium Hydroxide
Soap