Charring of cane sugar by sulphuric acid shows the property of dehydrating.

Sulphuric acid (H2SO4) is a strong acid and a powerful dehydrating agent. When it reacts with cane sugar (sucrose, C12H22O11), it removes water molecules from the sugar molecule, resulting in the formation of a black carbonaceous substance known as "char". This process is commonly referred to as charring.

Explanation:

1. Dehydrating property of sulphuric acid:
Sulphuric acid is highly hygroscopic, meaning it has a strong affinity for water and readily removes water molecules from other substances. In the case of cane sugar, sulphuric acid acts as a dehydrating agent by abstracting water molecules (H2O) from the sugar molecule.

2. Reaction between sulphuric acid and cane sugar:
The reaction between sulphuric acid and cane sugar can be represented as follows:

C12H22O11 + H2SO4 → 12C + 11H2O + H2SO4

In this reaction, sulphuric acid (H2SO4) acts as a catalyst for the dehydration of cane sugar. The acid abstracts water molecules from the sugar molecule, resulting in the formation of carbon (C) and water (H2O) as products. The released water molecules further react with sulphuric acid, creating more sulphuric acid as a byproduct.

3. Formation of char:
The carbon (C) produced during the reaction accumulates as a black residue, giving the charred appearance. This carbonaceous substance is a result of the incomplete combustion of the sugar molecule due to dehydration.

4. Significance of the reaction:
The charring of cane sugar by sulphuric acid is often used as a test to identify the presence of sugar in various substances. The formation of char indicates the presence of sugar, as other substances do not undergo charring when treated with sulphuric acid.

In conclusion, the charring of cane sugar by sulphuric acid demonstrates the dehydrating property of the acid. Sulphuric acid acts as a catalyst in removing water molecules from the sugar molecule, resulting in the formation of carbon and water. This reaction is commonly used to identify the presence of sugar in substances.