Class 7th science

 Topic - Exploring Substances: Acidic, Basic, and Neutral

we will discuss following things in our lecture -

Substances around us may be classifi ed as acidic, basic, and

neutral in nature.

 Extracts of lichen, red rose, red hibiscus, purple cabbage,

turmeric, etc., can be used to indicate the nature of substances.

 Substances that show diff erent colours in acidic and basic

solutions are called acid-base indicators.

 Acids turn the colour of blue litmus to red. Bases turn the

colour of red litmus to blue.

 Extract of red rose gives red colour in acidic solutions and

green colour in basic solutions.

 The yellow colour of turmeric turns red in basic solutions

but remains unchanged in acidic and neutral solutions.

 An acid and a base neutralise each other, forming salt and

water, along with the evolution of heat.

 Many day-to-day problems like a red ant bite, acidic or basic

nature of soil, and industrial waste can be attempted to be

managed by the process of neutralisation.