Metals and Non Metals | Class 10 full Chapter | Class 10 Science Chapter 3 in Animation

Summary

This video explains the extraction processes of metals, focusing on different methods for low, moderate, and high reactivity metals. It covers key techniques such as roasting, electrolysis, and the use of reducing agents. The video also addresses corrosion, its causes, and four key methods for prevention, including painting, greasing, galvanization, and making alloys. With clear examples and processes, the content offers an in-depth understanding of metal extraction and corrosion management.

Takeaways

• 😀 Low reactivity metals are typically extracted from sulfide ores through the process of roasting, which converts sulfides into metal oxides.
• 😀 For low reactivity metals like mercury, simple heating can reduce the metal oxide to obtain the metal.
• 😀 Moderate reactivity metals require reducing agents for their extraction, such as carbon in the case of zinc.
• 😀 High reactivity metals, due to their strong bonds in ores, need advanced methods like electrolytic reduction for extraction.
• 😀 Corrosion occurs when metals react with moisture or air, causing deterioration of the metal surface.
• 😀 Silver tarnishes and forms a black coating when exposed to air over time.
• 😀 Copper, when exposed to carbon dioxide and moisture, forms a greenish copper carbonate layer.
• 😀 Iron corrodes and forms rust, a brownish layer, when exposed to moisture and air.
• 😀 Corrosion can be prevented by painting metals to block moisture and air contact.
• 😀 Greasing metal surfaces is another effective method to prevent corrosion by preventing exposure to moisture and air.
• 😀 Galvanization involves coating iron or steel with a layer of zinc, protecting it from corrosion.
• 😀 Making alloys, such as brass (copper and zinc) or steel (iron and chromium), is another method of preventing corrosion, as alloys are more resistant than pure metals.

Q & A

What is the first step in the extraction of metals from ores?

The first step in the extraction of metals is refining the ores, where we prepare metal salts or solutions, especially for copper.

How are low-reactivity metals extracted?

Low-reactivity metals are typically found in sulfide ores, which are converted into metal oxides through a process called roasting, after which reduction through heating is often sufficient to extract the metal.

What happens when mercury sulfide is heated in the presence of oxygen?

When mercury sulfide is heated in the presence of oxygen, it undergoes roasting and is converted into mercury oxide (a metal oxide), releasing sulfur dioxide (SO2). This oxide can then be reduced to obtain mercury.

Why do moderate-reactivity metals require reducing agents for extraction?

Moderate-reactivity metals, like zinc, have stronger bonds in their ores that require external reducing agents, such as carbon, to break them and release the metal.

How are high-reactivity metals extracted?

High-reactivity metals require advanced extraction techniques, such as electrolytic reduction, due to their very strong bonds in ores that cannot be easily broken by simple heating or other basic methods.

What is the process of electrolytic reduction used for?

Electrolytic reduction is used for extracting high-reactivity metals by passing an electric current through a solution to break the bonds in the metal’s ore and release the pure metal.

What is corrosion in metals?

Corrosion is the gradual degradation of metals when exposed to air or moisture over time. It results in the formation of compounds such as rust (on iron) or tarnish (on silver).

How does moisture contribute to corrosion?

Moisture facilitates the reaction between the metal and oxygen in the air, leading to the formation of metal oxides or other compounds, such as rust on iron or tarnish on silver.

What are the four methods of preventing metal corrosion?

The four main methods of preventing corrosion are: 1) Painting to block moisture contact, 2) Greasing the metal surface, 3) Galvanization (coating metal with zinc), and 4) Making alloys that resist corrosion.

How does galvanization prevent corrosion in metals?

Galvanization involves coating iron or steel with a layer of zinc. Zinc protects the metal by acting as a sacrificial anode, preventing the iron or steel from corroding.