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प्रश्न
Why does evaporation causes cooling and why is water used in hot water bottles?
उत्तर
The specific latent heat of vaporization of water is 2260 J/g = 538 calories/g. Thus when water evaporates it absorbs large amount of latent heat and thus cooling is caused. The specific heat capacity of water is 4.2 J/kg°C = 1 cal/g°C which is quite high and this is the reason for using wafer in hot water bottles.
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संबंधित प्रश्न
A refrigerator converts 100g of water at 20℃ to ice at – 10℃ in 73.5 min. Calculate the average rate of heat extraction in watt. The specific heat capacity of water is 4.2 J kg-1 K-1, specific latent heat of ice is 336 J g-1 and the specific heat capacity of ice is 2.1 J kg-1 K-1.
When a liquid is getting converted into solid, the latent heat is ………………………………
Water expands on reducing its temperature below ______°C.
Define specific latent heat of vaporization of a substance.
Name two factors on which the heat absorbed or given out by a body depends.
Give one consequence of the high specific latent heat of fusion of ice.
Explain the statement; “The specific latent heat of vaporization of wafer is 2260 × 103 J/kg”.
Derive an expression for the amount of heat given out or taken up, when its temperature falls or rises by t°C.
What observation you will record and how will you determine the specific latent heat of fusion of ice?
Steam at 100°C is passed over 1000 g of ice at 0°C. After some time, 600 g of ice at 0°C is left and 450 g of water at 0°C is formed. Calculate the specific latent heat of vaporization of steam (Given: specific heat capacity of water = 4200 J/kg°C, specific latent heat of fusion of ice = 336,000 J/kg.)
1 kg of water is contained in a 1.25 kW kettle. Assuming specific heat capacity of water = 4.2 J/g °C and specific latent heat of vaporization = 2260 J/g, calculate:
(i) the time taken for the temperature of water to rise from 25°C to its boiling point,
(ii) the mass of water which evaporates per minute from the boiling water.
Define boiling point of a liquid.
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Write the name.
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Define specific latent heat capacity
600 g of copper at 50°C is mixed with lOOOg water at 20°C. Find the final temperature of the mixture. The specific heat capacity of copper is 0.4 Jg-1°C-1 and that of water is 4.2 Jg-1°C-1
20 g of ice at 0°C absorbs 10,920 J of heat energy to melt and change to water at 50°C. Calculate the specific latent heat of fusion of ice. Specific heat capacity of water is 4200 J kg-1 K-1.
