Matter can exist in three physical state solid, liquid, gas. We can change the physical state of matter by two way.
- By effect of changing the temperature.
- By effect of changing pressure.
I) By effect of changing temperature:
Solid to Liquid change
The process in which solid change into liquid with increase in temperature ( heat) Is called is called melting/fusion.
Melting:
The temperature at which Solid substance melt And change into a liquid at atmospheric pressure.
(Or) The temperature at which a solid melt to become a liquid at the atmospheric pressure its called it’s melting point. The melting point of ice is 0°C . It may also be written as 273K.
Liquid to Solid (Freezing)
The process of changing a liquid into solid by cooling is called freezing,. Freezing is the reverse process of melting. Freezing means solidification.
Freezing Point:
The temperature at which liquid of a substance change into solid at atmospheric pressure is called freezing point.
Liquid into gas (Vaporization/Boiling)
The process in which liquid changes to gaseous form when it is heated is cat vaporization. There are two process of vaporization 1.boiling 2.evaporation
Boiling:
The process in which liquid change into gaseous form when it is heated at fixed temperature (boiling point) is called boiling.
Evaporation:
The surface process in which liquid change into gaseous form when it is heated below the boiling point is called evaporation.
Factor Effecting on evaporation:
- Surface Area
- Increase in temperature
- Decrease in humidity
- Nature of liquid
- We spread wet clothes’ to dry them into air.
- Evaporation is faster in summer than winter
Example: surface of water evaporate from sea, ocean, lakes due to heat of the sun. Water steam change into gaseous form at temperature of 100°C.
Evaporation causes cooling:
- We put acetone on our palm (cooling effect)
- We wear cotton clothes in summer.
- Water is kept in earthen pot in summer
- People sprinkled water on ground in summer etc.
Gas into liquid (condensation)
The process in which gas change into liquid by the process of cooling is called condensation. Condensation is reverse of boiling . When a gas is cooled enough (by lowering temperature) then it’s particles losses so much kinetic energy that the slow down move closer to together until they start being attracted to each other, and form a liquid.
Example: Any utensil taken out refrigerator, molecule of water vapour from the atmosphere come in contact with cold sight and form water drop.
Solid to gas (sublimation)
The process in which solid change into gaseous form or state directly without passing through liquid state when it is heated called sublimation. In this process energy is gain by matter.
Example:
- Iodine crystals solid form change into gaseous form (Violet fumes) without changing in liquid form.
- Dry ice carbon dioxide in solid form change into carbon dioxide gas when kept at room temperature.
- Ammonium chloride solid form change into gaseous form when heated.
Gas into solid (de sublimation/ deposition)
The process in which gas change into its solid form without changing into liquid form when it is cooled is called deposition/ de sublimation.
Deposition occur at the temperature below 0°C , or below freezing point.
Example: frost form on the cool winter morning.
II) By Effect of changing Pressure
Inter conversion of matter
When gas is compressed , The intermolecular space between the particles Decrease and ultimately It will be converted into liquid.
- On increase pressure, intermolecular force increase
- Gas can be liquidified by applying pressure on room temperature.
- By cooling atmospheric pressure. Gas particles are push and closer to each other
- Dry ice is stored under high pressure at it sublime At -78°C . It doesn’t wet at the surface like ice does.
Question answer
1) What is evaporation?
Answer: The surface process in which liquid change into gaseous form when it is heated below the boiling point is called evaporation.
2) Explain the condensation?
Answer: The process in which gas change into liquid by the process of cooling is called condensation. Condensation is reverse of boiling . When a gas is cooled enough (by lowering temperature) then it’s particles losses so much kinetic energy that the slow down move closer to together until they start being attracted to each other, and form a liquid.
Example: Any utensil taken out refrigerator, molecule of water vapour from the atmosphere come in contact with cold sight and form water drop.
3) What is sublimation?
Answer: The process in which solid change into gaseous form or state directly without passing through liquid state when it is heated called sublimation. In this process energy is gain by matter.
Example:
Iodine crystals solid form change into gaseous form (Violet fumes) without changing in liquid form.
4) What is melting point?
Answer:The temperature at which Solid substance melt And change into a liquid at atmospheric pressure.
(Or) The temperature at which a solid melt to become a liquid at the atmospheric pressure its called it’s melting point. The melting point of ice is 0°C . It may also be written as 273K.
5) Write down the factor effecting on evaporation?
Answer: Factor Effecting on evaporation are following
- Surface Area
- Increase in temperature
- Decrease in humidity
- Nature of liquid
- We spread wet clothes’ to dry them into air.
- Evaporation is faster in summer than winter
6) What is freezing point?
Answer: The temperature at which liquid of a substance change into solid at atmospheric pressure is called freezing point.