Question

why should a magnesium ribbon be cleaned before burning in air?​

Answer 1

Answer:

Magnesium ribbon should be cleaned with sandpaper before burning in the air. ... To remove the Magnesium oxide layer from the ribbon which may prevent or slow down the burning of magnesium ribbon. Unwanted impurities deposited on the magnesium ribbon can be removed and only pure magnesium can be used for the reaction.

Explanation:

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Answer 2

$\bf{\underline{Answer}}$

A magnesium ribbon must be cleaned before burning in air because magnesium when exposed to air reacts with oxygen which leads to the formation of magnesium oxide on the surface of the magnesium ribbon. The formation of a layer of magnesium oxide on the magnesium ribbon might slow down the reaction. So it is necessary to remove the layer of magnesium oxide from the surface of magnesium. Hence it must be cleaned before performing a reaction.

$\bf{\underline{Additional\:Informations}}$

$\bf{\underline{Activity\:for\:burning\:of\:magnesium\:ribbon\:in\:air}}$

AIM :-

To burn the magnesium ribbon in air and see what product is formed.

Materials Required:-

• Magnesium ribbon

• Burner

• A pair of tong

• Watch - glass.

Procedure:-

1. Take a magnesium ribbon of length 3-4 cm and clean it with a sandpaper.

2. Hold the ribbon with a pair of tong and burn it in the burner.

3. Collect the burnt residue in a watch-glass

Observation:-

We observe that the magnesium ribbon burns with a dazzling white flame.

Conclusion:-

The left residue after burning of magnesium ribbon is magnesium oxide.

Caution:-

The magnesium ribbon must be held as far as possible from the eyes while burning it.

$\bf{\underline{Some \:more\: points:-}}$

Magnesium ribbon when burnt in air leads to the formation of magnesium oxide.

Chemical formula for this reaction:-

$\sf{2Mg + O_2 \longrightarrow 2MgO}$

This reaction is a type of oxidation reaction and also a type of combination reaction.

In this reaction Magnesium is gaining oxygen. Hence oxidation reaction.

In this reaction two substances i.e., Magnesium and oxygen are combining together to form a single product i.e., Magnesium oxide. Hence Combination reaction.