Question

1. You are given three materials in the form
of solutions-citric acid, magnesium
hydroxide and sodium sulphate. Describe
how you will classify the substances
as acidic, basic and neutral using
purple cabbage solution.​

Answer 1

Explanation:

in citric acid purple cabbage remains in purple colour and in magnesium hydroxide the colour of cabbage will green and in sodium sulphate it will remain same

Answer 2

Answer:

• A purple cabbage solution made from its juice acts as a natural pH indicator.
• This is due to the presence of the purple pigment anthocyanin which will turn its original colour according to the acidity of the medium.
• Colour indicators are used to find the pH of a solution based on the hydrogen content of the solution.
• This is matched with the pH indicator scale from 0 to 14 with 7, where solutions with pH of 0 to 7 – acidic, 7 – neutral, 8 to 14 - basic in nature.
• The purple cabbage solution will retain its original purple colour in neutral solutions; will change to reddish pink in acidic solutions, and to bluish-green or yellow in basic solutions.

Based on the purple cabbage indicator test, the following substances will be classified as:

1. Citric acid: The pH is around 2, it will be acidic.
2. Magnesium hydroxide: The pH is around 10, it will be basic.
3. Sodium sulphate: The pH is 7, it will be neutral.