Why some metals become dull after some time?

It is the effect of air and moisture. Metals like iron, alluminium etc. reacts with moist air and get oxidised and they lose their shine.

What is the process called which make surface of metals dull and faded?

When some metals get exposed to air there is an oxidation process occurring on the outer layer of the metal. Due to the oxidation; a new layer covers the existing metal; hiding its original view; giving it a dull appearance. Almost all metals combine with oxygen to form metal oxides.

Why does surface of aluminium become dull and loss its shine after some days?

This is because aluminium reacts with oxygen present in air to form a thin layer of aluminium oxide. This oxide layer is very stable and prevents further reaction of aluminium with oxygen. Because of this layer surface of alluminium turns into dull colour after some few days.

Why shining surface of metal is tarnished after some time?

The surface of metals undergo oxidation under the influence of air, moisture and chemicals such as acids, which is called corrosion. Because of this process, the shining surface of metals is tarnished after some time. For example, iron turns reddish brown due to corrosion and silver turns greyish due to this process.

Why do metals have dull appearance?

The surface of some metal acquires a dull appearance because metals form a thin layer of oxides, carbonates or sulphides on their surface when exposed to air for a long time.

Why does metal lose their shine after exposure to air?

Why? The metals lose their shine or lustre on keeping in the air for a long time due to formation of a thin layer of oxide, carbonate or sulphide on their surface by the slow action of various gases present in the air. This is known as Rusting.

Why some metals like iron or copper lose their lustre on exposure to air?

The metals lose their shine or lustre on keeping in the air for a long time due to formation of a thin layer of oxide, carbonate or sulphide on their surface by the slow action of various gases present in the air. This is known as Rusting.

How we can prevent corrosion?

There are several cost effective ways to prevent corrosion including:

1. Use non-corrosive metals, such as stainless steel or aluminium.
2. Make sure the metal surface stays clean and dry.
3. Use drying agents.
4. Use a coating or barrier product such as grease, oil, paint or carbon fibre coating.

Why moist air are not good for some metals?

Moist air and acidic gases are not good for some metals because of the corrode the metal like iron and it can make them into the form of weak state. Hence it cannot be make use in the major people.

Why do metal objects lose their luster after a while?

Explanation: Metals lost their lustre after a while because it react with air and moisture. Metals like iron,aluminium etc. reacts with moist air and get oxidised and lost their shine.

Why do iron particles lose their shine gradually?

Answer : Iron articles lose their shine gradually when exposed to the atmosphere. Iron is a reactive metal and when exposed to the atmosphere it reacts with atmospheric oxygen and moisture to form an iron oxide, commonly called rust. As a result, iron articles lose their shine gradually.

Why do metals object lose their lustre after a while?

Why surface of some metals acquire a dull appearance when exposed?

Explain why surface of some metals acquire a dull appearance when exposed to air for a long time… The surface of some metals acquires a dull appearance when exposed to air for a long time due to:- the formation of a thin layer of oxide, carbonate or sulphide on their surface by the slow action of the various gases present in air.

Why do some metals oxidise faster than others?

This is common with many metals, however some are naturally less susceptible than others to oxidation, which is why metal alloys like stainless steel are popular – given they retain their lustre for a much longer time when exposed to air and water. This is due to a chemical reaction between the metal and the gases in the atmosphere.

Why is aluminum foil unreactive to gases?

This is due to a chemical reaction between the metal and the gases in the atmosphere. Aluminium which reacts to form a layer of aluminium oxide on its surface, the reason why aluminium foil is unreactive unless the oxide layer is removed.

What do you mean by corrosion?

⚫ Surface o some metals acquires a dull appearance because they react with air or water in the environment to form undesirable compounds (such as Oxides)..This process is called Corrosion. ⚫For example:- Silver tarnishes, Copper develops a green coating, iron loses it’s lustre. The corrosion of iron is called Rusting.