NCERT Solution for Class Tenth Science Chapter 3
Metals and Non-metals
CBSE NCERT Book Session-2022-2023
Exercises Questions
Page No-21
Questions No-
Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).
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Copper does not react with cold water, hot water, or steam. However, iron reacts with steam. If the hot water tanks are made of steel (an alloy of iron), then iron would react vigorously with the steam formed from hot water.
3Fe+4H₂o → Fe₃O₄ + 4H₂
That is why copper is used to make hot water tanks, and not steel.
Iron react with steam, whereas copper does not reat with cold water, hot water, or steam. So, hot water tanks are made of steel (an alloy of iron), then iron reacts with the steam formed by hot water.
3Fe + 4H2O → Fe3O4 + 4H2
Iron+ Steam –> Iron oxide + Hydrogen
Therefore copper is used to make hot water tanks, and not steel.
Copper is commonly used to make hot water tanks, while steel (an alloy of iron) is not typically used for this purpose. There are several reasons for this choice:
1. Corrosion Resistance: Copper is highly corrosion-resistant, especially in the presence of hot water. It forms a protective layer (copper oxide) on its surface that further inhibits corrosion. In contrast, steel is prone to rust (iron oxide formation) when exposed to water and oxygen, which can compromise the tank’s integrity over time.
2. Heat Conductivity: Copper is an excellent conductor of heat. This means it heats up quickly and efficiently, which is desirable for heating water. It also retains heat well, keeping the water warm for longer periods. Steel, while a good conductor of heat, is not as efficient as copper.
3. Lightweight: Copper is relatively lightweight, making it easier to handle during tank manufacturing, installation, and maintenance. Steel, especially when used for large tanks, can be much heavier and cumbersome.
4. Aesthetic Appeal: Copper has a visually appealing reddish-brown color that many people find attractive. It is often used for exposed hot water tanks or tank exteriors, contributing to their aesthetics.
5. Longevity: Copper hot water tanks can have a long service life due to their corrosion resistance and durability. While steel tanks can be coated to reduce corrosion, copper tanks do not require such coatings.
6. Compatibility: Copper is compatible with different water qualities and does not react with water as aggressively as steel can when it comes to potential water quality issues.
7. Reduced Scaling: Copper is less prone to scaling, which is the buildup of mineral deposits in the tank, compared to steel. Scaling can reduce the efficiency of the hot water tank.
Despite these advantages, it’s worth noting that copper hot water tanks are typically more expensive than their steel counterparts. However, the longevity and efficiency of copper tanks often justify the initial investment for many consumers, especially in areas with aggressive water quality or where aesthetics are important.