i.2. How do Natural Indicators such as Litmus, Turmeric and China Rose reflect Chemical Dynamics in Acid-Base Reactions?

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i.2. How do Natural Indicators such as Litmus, Turmeric and China Rose reflect Chemical Dynamics in Acid-Base Reactions?

Turmeric, litmus, china rose petals (Gudhal), etc., are some of the naturally occurring indicators.

To prepare lime water, dissolve some lime (chuna) in water. Stir the solution and keep it for some time. Pour a little from the top. This is lime water.

Litmus: Nature and Significance of a Natural Dye	The most commonly used natural indicator is litmus extracted from lichens. Colour: It has a mauve (purple) colour in distilled water. Observed Changes: When added to an acidic solution, it turns red and when added to a basic solution, it turns blue. Presence: It is available in the form of a solution, or in the form of strips of paper, known as litmus paper (red and blue litmus paper). Neutral Solution: The solutions which do not change the colour of either red or blue litmus are known as neutral solutions. These substances are neither acidic nor basic.
Turmeric: Red Stain and the Basic Soap Solution	Turmeric stain on white shirt turns to red when it is washed with soap. It is because the soap solution is basic.
China Rose (Gudhal): Acidity in Pink and Alkalinity in Green	China rose (Gudhal) indicator turns acidic solutions to dark pink (magenta) and basic solutions to green.

Litmus solution is a purple dye, which is extracted from lichen, a plant belonging to the division Thallophyta. When the litmus solution is neither acidic nor basic, its colour is purple. There are many other natural materials like red cabbage leaves, turmeric, coloured petals of some flowers such as Hydrangea, Petunia and Geranium, which indicate the presence of acid or base in a solution. These are called acid-base indicators or sometimes simply indicators.

Acid rain

As the name indicates the rain containing excess of acids is called an acid rain.
The rain becomes acidic because carbon dioxide, sulphur dioxide and nitrogen dioxide (which are released into the air as pollutants) dissolve in rain drops to form carbonic acid, sulphuric acid and nitric acid respectively.
Acid rain can cause damage to buildings, historical monuments, plants and animals.

Other Topics	Details
How do Synthetic indicators provide insights into the Chemical Dynamics of Acids and Bases?	Synthetic indicators such as methyl orange and phenolphthalein are used to test for acids and bases. When the solution is basic, phenolphthalein gives a pink colour and when the solution is acidic, it remains colourless.
Olfactory indicators and their Aromatic responses to Acidic and Basic Environments	There are some substances whose odour changes in acidic or basic media. These are called olfactory indicators