What is latent heat?
Heat energy absorbed or released during a change of state without a temperature change.
Name the two types of latent heat.
Latent heat of fusion and latent heat of vaporization.
What is latent heat of fusion?
The heat required to convert a solid to a liquid at constant temperature.
What is latent heat of vaporization?
The heat required to convert a liquid to gas without temperature change.
What is specific latent heat?
The heat required to change the state of 1 kg of a substance without temperature change.
What is the specific latent heat of fusion of ice?
\( L_f = 33{,}600 \, \text{J/kg} \)
Give the formula for heat energy during fusion.
\( Q = M L_f \)
What is the specific latent heat of vaporization of water?
\( L_v = 2.26 \times 10^6 \, \text{J/kg} \)
Give the formula for heat energy during vaporization.
\( Q = M L_v \)
Define evaporation.
Evaporation is the process where a liquid changes into gas from its surface at any temperature.
List three factors that affect the rate of evaporation.
Temperature, pressure, surface area, wind, and nature of liquid.
Why does evaporation cause cooling?
Because latent heat is absorbed from the surroundings during the process.
What is boiling point?
The temperature at which the saturated vapor pressure of a liquid equals atmospheric pressure.
How does pressure affect boiling point?
Increasing pressure raises the boiling point; decreasing pressure lowers it.
What is humidity?
Humidity is the amount of water vapor present in the air.
Define relative humidity.
\[ \text{R.M} = \frac{m}{M} \times 100\% = \frac{\text{V.P}}{\text{S.V.P}} \times 100\% \]
What instrument is used to measure relative humidity?
A hygrometer, which includes dry and wet bulb thermometers.
What is dew point?
The temperature at which air becomes saturated and condensation begins.
How does dew form?
When air cools below the dew point, excess water vapor condenses into droplets.
What are mist and fog?
Mist is water droplets suspended near the ground; fog is a denser form of mist.
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