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 Table
- Result
- Precautions
- Frequently Asked Questions – FAQs
Aim
To carry out the Burning of magnesium ribbon in air and classify it as physical and chemical changes.
Materials Required
Magnesium Ribbon, Burner, Tongs, Watch Glass, pH paper Strip/Red Litmus Paper.
Theory
Magnesium is an extremely active metal. Magnesium oxide is formed when it reacts with oxygen.
During this process, two elements, magnesium and oxygen, react to form the compound magnesium oxide. Such reactions are referred to as combination reactions.
Magnesium oxide is basic in nature because it forms magnesium hydroxide when dissolved in water.
Magnesium oxide changes the colour of the red litmus solution to blue.
Also Read: Experiment on Burning of magnesium ribbon in air Viva Questions
Procedure
1. Impurities are removed from a piece of magnesium ribbon by rubbing it with sandpaper.
2. Use a pair of tongs to hold the magnesium ribbon over the watch glass or china dish.
3. Light the magnesium ribbon on the bunsen burner. Gather ash in a watch glass or china dish.
4. Bring the ash with moist red litmus paper.
Observation Table
| S. No | Experiment | Observation | Inference |
|---|---|---|---|
| 1. | Rub magnesium ribbon with sandpaper. | It looks silvery white. | The colour of magnesium ribbon/metal is silvery white. |
| 2. | Burn magnesium ribbon. | It burns with a dazzling white flame. | Magnesium burns in the air to form magnesium oxide. |
| 3. | Bring moist red litmus paper in contact with the ash of the magnesium ribbon. | Red litmus paper turns blue. | MgO is basic is nature. |
Result
- Magnesium is a silver-white metal.
- Mg burns in the air, emitting a bright white flash, and then combines with oxygen to form basic magnesium oxide.
2Mg + O2 → 2MgO - MgO is a basic element.
- The experiment shows that burning magnesium ribbon in air is a direct combination reaction.
- The formation of magnesium oxide is a chemical change.
Precautions
1. The sandpaper should be used to clean the magnesium ribbon.
2. Hold the magnesium ribbon with tongs while it burns.
3. Avoid looking directly at the bright light associated with burning Mg. Wear sunglasses.
4. Do not come into contact with white powder or magnesium oxide.
Frequently Asked Questions
Q1
What is the colour of the flame when magnesium burns in the air?
Magnesium burns with a dazzling white flame.
Q2
Does Magnesium hydroxide have any effect on litmus paper?
Yes, on testing Magnesium hydroxide with litmus paper, it turns red litmus to blue.
Q3
Note down the observations for the experiment.
Some of the observations of the experiment are-
- Magnesium burns with dazzling white flame.
- A white powdery mass of magnesium oxide is formed.
Q4
What is the equation for the reaction?
The equation for the reaction is as follows-
Mg + O2 → MgO
Q5
What type of reaction is the burning of magnesium ribbon?
The burning of magnesium ribbon is a combination reaction. This is because magnesium reacts with oxygen to form a single product magnesium oxide
