Experiment on the reaction of Heating of copper sulphate crystals and classify it as physical or chemical changes

A physical change occurs when there is no change in the composition of a substance and no change in the chemical nature of the substance.

The interconversion of state occurs during physical change.

SOLID ⇄ LIQUID ⇄ GAS

A chemical change is a change that causes a change in the chemical properties of matter, resulting in the formation of a new substance. As an example, consider the burning of oil or fuel.

Heat is evolved or taken in, the formation of bubbles, gas, and fumes, as well as a change in the colour of the reactants, can take place when they form a product.

Reactants → Products

A + B → C (Chemical reaction)

Table of Contents

• Aim
• Materials Required
• Theory
• Procedure
• Observation
• Result
• Precautions
• Frequently Asked Questions – FAQs

Aim

To carry out the reaction of Heating of copper sulphate crystals and classify it as physical or chemical changes.

Materials Required

Hydrated copper sulphate, Test Tube, Test Tube Holder, Bunsen Burner, pH paper or

Blue Litmus Paper.

Theory

CuSO₄.5H₂O is the chemical formula for copper sulphate crystals. It is known as copper sulphate pentahydrate. It has a water content of five moles per mole of copper sulphate. Copper sulphate pentahydrate has a blue colour due to water hydration. It loses water molecules and transforms into white anhydrous copper sulphate when heated.

Procedure

1. Heat copper sulphate crystals in a dry test tube.
2. Observe the colour of the copper sulphate crystals after heating.
3. Observe the water droplets along the sides of the boiling tube.
4. Remove the test tube from the flame and allow it to cool for some time.
5. Add 2 – 3 drops of water to the sample of heated copper sulphate.

Observation

1. The colour of the copper sulphate crystals changes from blue to white on heating.
2. Water droplets can be clearly observed on the walls of the boiling tube.
3. White copper sulphate turns blue on adding 2 – 3 drops of water.

Result

1. Copper sulphate crystals contain water of crystallisation.
2. Hydrated copper sulphate crystals lose their water of crystallisation on being heated and become anhydrous.
3. Anhydrous copper sulphate changes to hydrated copper sulphate.
4. It is a reversible chemical change.

Precautions

1. Copper sulphate is a highly toxic substance. It is not to be touched or tasted.
2. Sulphuric acid is formed when sulphur trioxide reacts with atmospheric moisture. As a result, contact with sulphur trioxide should be avoided.
3. Copper sulphate should be gently heated at the start of the experiment. However, after the formation of anhydrous copper sulphate, the test tube should be strongly heated.