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प्रश्न
What do you understand by the ‘latent heat of vaporization’ of a substance?
उत्तर
The latent heat of vaporization of a given liquid is the heat required to convert one kilogram of the liquid into vapour at its boiling point without any change of temperature. It is measured in joule per kilogram. The latent heat of vaporization of water is 2260 × 103 J/kg. It means that we need 2260 × 103 J of heat to convert 1 kg of water at its boiling point into steam.
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संबंधित प्रश्न
State two characteristics of a good thermion emitter.
State the effect of an increase of impurities on the melting point of ice.
1 g ice of 0℃ melts to form 1 g water at 0℃. State whether the latent heat is absorbed or given out by ice.
- Which requires more heat: 1 g ice at 0℃ or 1 g water at 0℃ to raise its temperature to 10℃?
- Explain your answer in part (a).
Liquid ammonia is used in ice factory for making ice from water. If water at 20°C is to be converted into 2 kg ice at 0°C, how many grams of ammonia are to be evaporated? (Given: The latent heat of vaporization of ammonia = 341 cal/g)
Explain the following temperature Vs. time graph:
Define the following terms:
(i) Latent heat,
(ii) Latent heat of fusion of ice.
What is the name given to the energy absorbed during a phase change?
What happens to the heat supplied to a substance when the heat supplied causes no change in the temperature of the substance?
Why does weather become pleasant when it starts freezing in cold countries?
Why do we feel much comfortable when we sit under a moving fan especially when our body is sweating?
State the main precautions to be taken in finding the latent heat of steam.
Match the columns.
| Column A | Column B |
| 1) Specific latent heat of fusion | a) Air saturated with vapour |
| 2) Specific latent heat of vaporisation | b) Solid converts into liquid |
| 3) Dew point temperature | c) liquid converts into gas |
Match the columns.
| Column A | Column B |
| 1) Absolute humidity | a) J or cal |
| 2) Latent heat | b) J/kg °C |
| 3) Specific heat capacity | c) kJ/kg |
| 4) Heat | d) no unit |
| e) kg/m3 |
Write scientific reason.
The bottom of some steel utensils used for cooking is copper.
Specific latent heat of a substance ______.
Calculate the total amount of heat energy required to melt 200 g of ice at 0°C to water at 100°C. (Specific latent heat of ice = 336 Jg-1, specific heat capacity of water = 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.
