Steam at 100°C is more effective in heating than water at the same tem

Steam at 100°C is more effective in heating than water at the same temperature because

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steam is in the gaseous state and water is in the liquid state

steam has an additional heat known as 'latent heat of vaporization'

water has hydrogen bonds but steam does not

transfer of heat from steam is easier than water

Answer is Right!

Answer is Wrong!

This question was previously asked in

UPSC CAPF – 2011

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The correct option is B. Steam at 100°C is more effective in heating than water at 100°C because steam possesses additional energy in the form of latent heat of vaporization. This is the energy absorbed by water to change its state from liquid to gas at its boiling point (100°C) without a change in temperature. When steam comes into contact with a cooler surface, it condenses back into water at 100°C, releasing this large amount of latent heat, which is then transferred to the surface being heated. Water at 100°C does not have this stored latent heat to release upon changing state.

The question asks why steam at the same temperature as water is a more efficient heating medium. The key concept is latent heat.

The latent heat of vaporization of water at 100°C is approximately 2260 kJ/kg (or 540 cal/g). This means that condensing 1 kg of steam at 100°C to water at 100°C releases 2260 kJ of heat, which is significantly more than the heat released by simply cooling 1 kg of water from 100°C. This large amount of heat released upon condensation makes steam very effective for heating applications like steam engines, industrial processes, and steam burns.

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