What is the Specific Latent Heat of Fusion?
The amount of heat energy absorbed at constant temperature by unit mass of a solid to convert into liquid phase is called the Specific Latent Heat of Fusion.
What is the Specific Latent Heat of Vaporization?
The amount of heat energy absorbed at constant temperature by unit mass of a liquid to convert into gaseous phase is called the specific latent heat of vaporization.
What is regelation?
The ice converts into liquid due to applied pressure and then re-convert into ice again when the pressure is removed is called regelation.
Why does the water get converted into ice again as soon as the pressure is removed?
- The melting point of ice becomes lower than 0 degree Celsius due to pressure and at 0° celsius the ice gets converted into water.
- As soon as the pressure is removed, the melting point is restored to zero degree Celsius and water gets converted into ice again.
State the anomalous behaviour of water.
- In general, when a liquid is heated up to a certain temperature it expands and when school it contracts.
- Water shows a special and exceptional behaviour if we heat water from 0 degree Celsius up to 4 degree Celsius, it contracts instead of expands at 4 degree Celsius and its volume is minimum.
- If the water is heated further it expands and its volume increases.
- The behaviour of water between the temperature from 0 degree Celsius to degree Celsius is called anomalous behaviour of water.
"Though the heat energy is supplied to water over 100 degree Celsius, its temperature does not rise." Why?
- The heat energy is observed by water at this temperature and used to break the bonds between molecules of the liquid and convert the liquid into gaseous state.
- Thus during transmission from liquid phase to gaseous phase heat energy is observed by the liquid, but its temperature does not change.
How can the aquatic plants and animals survive even when the atmospheric temperature goes below zero degree celsius?
- Anomalous behaviour of water occur between 0° to 4° Celsius.
- Below 4 degree Celsius density of water decreases and volume increases.
- At the bottom of water sources, the temperature remain constant at 4 degree Celsius because of high density and low volume whatever the atmospheric temperature below zero degree celsius.
- At the 4 degree celsius temperature at the bottom aquatic plants and animals can survive.
What is humidity?
- The moisture in the atmosphere is called humidity.
- Due to constant evaporation of water, water vapours is always present in atmosphere and pressure of water vapour in the air mater it moist.
What is dew point temperature?
If the temperature of unsaturated air is decreased, temperature is reached at which the air becomes saturated with water vapour. This temperature is called the dew point temperature.
Define the Saturated Air and Unsaturated Air.
Saturated air:
When air contains maximum possible water vapour it is said to be saturated with water vapour at that temperature.
Unsaturated air:
When air contains water vapour less than its capacity to hold water vapour at a temperature, it is said to be an saturated with water vapour.
"Morning dew appears early in the morning." Why?
- If the temperature of unsaturated air is decreased, temperature is reached at which the air becomes saturated with water vapour. This temperature is called the dew point temperature.
- During cold night, the temperature of air may fall to the dew point or even below the dew point.
- If the temperature falls below the dew point, the excess of water vapours in air condenses on the surface of cold bodies and due is formed. And in the morning we see the dew on the grass and on other bodies also.
"During winter season, white trails appear at the bank of flying plane in a clean sky." Why?
- As the plane flies, the vapour released by the aeroplane engine condenses and forms clouds.
- If the surrounding air is having more relative humidity, it takes a long time for the white trail formed by condensation of the vapour to disappear.
- If relative humidity of the surrounding air is less, either the size of the white trail may be small or it may not even get formed.
What is the specific heat capacity?
- The amount of heat energy required to raise the temperature of unit mass of an object by 1 degree Celsius is called specific heat of that object.
- The specific heat capacity is a denoted by the letter C. The SI unit of specific heat is j/kg°c and the CGS unit is cal/g°c.
State the principle of heat exchange.
- If heat is exchanged between a hot and cold object, the temperature of the cold object goes on increasing due to the gain of energy and the temperature of the hot object goes on decreasing due to loss of energy.
- The change in temperature continuous till the temperature of both the objects attend the same value.
"Heat energy lost by the hot object = heat energy gained by the cold object." This is called as principle of heat exchange.
What is absolute humidity?
- The vapour content in air is measured using a physical quantity called absolute humidity.
- The mass of vapour present in a unit volume of air is called absolute humidity. Generally absolute humidity is measured in kg/m^3.
What is relative humidity?
The ratio of actual mass of water vapour content in the air for a given volume and temperature required to make the air saturated with vapour at the temperature is called the relative humidity.
% of relative humidity = actual mass of water vapour content in air in a given volume / mass of vapour needed to make the air saturated in that volume *100
