Question

Classify the following, as a physical or a chemical change. Give reasons: Change in the colour of black tea on adding lemon juice to it.

Answer 1

Physical Change:

• The change in which a substance undergoes a change in its physical properties in which no new substance get formed is known as a physical change.
• A physical change is generally known to be reversible in nature.

Chemical Change:

• A change in which one or more new substances get formed is known as a chemical change.
• A chemical change is generally irreversible in nature.

Change in the color of black tea on adding lemon juice to it:

• A change in the color of black tea on adding lemon juice to is known as a chemical change.
• Here lemon juice, which is a source of Citric acid, Ascorbic acid, and Malic acid, reacts with the Flavin antioxidants present in black tea to change the color of the tea.
• Also, the color of the black tea cannot be reversed back.

Hence, Change in the colour of black tea on adding lemon juice to it is a chemical change.