NCERT Solutions for Class 7 Science Chapter 6
Important NCERT Questions
7th Chapter 6 Physical and Chemical Changes
NCERT Books for Session 2022-2023
CBSE Board and State Board
Questions No: 10
Explain why rusting of iron objects is faster in coastal areas than in deserts.
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Rusting of iron objects occurs at varying rates based on environmental conditions:
1. Coastal Areas:
– Higher Humidity: Coastal regions have elevated humidity due to proximity to water bodies like oceans or seas. This increased moisture content accelerates rusting by providing more water for the oxidation process.
– Salt Content: Sea spray and winds from the ocean carry salt particles into the air, enhancing rust formation. Salt acts as an electrolyte, speeding up the corrosion process on iron surfaces.
2. Deserts:
– Low Humidity: Deserts experience extremely low humidity levels, limiting moisture in the air. The scarcity of water hinders rust formation by reducing the available water necessary for oxidation.
– Minimal Salt Content: Deserts generally have minimal salt content in the air compared to coastal areas. The absence of salt diminishes the rate of corrosion, slowing down rust formation on iron objects.
3. Oxygen Availability:
– Similar in Both Areas: Both coastal areas and deserts have sufficient oxygen for the rusting process. Oxygen reacts with iron and water to form iron oxide (rust).
In summary, coastal areas witness faster rusting due to heightened humidity, increased moisture, and elevated salt content from nearby water bodies. Conversely, deserts experience slower rusting owing to low humidity and minimal salt concentration, limiting moisture and impeding the oxidation process on iron surfaces.
For rusting, the presence of both oxygen and moisture (water vapour) is required. In coastal areas the quantity of moisture content in air is high (highly humid) as compared to desert regions (low humid), so the rusting becomes faster in coastal areas.
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