the release of pressure can change the state of the matter from liquid to gas. explain this process
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Answers
Answer:
Explanation:
What is the process of changing from liquid to a gas?
Vaporization of a sample of liquid is a phase transition from the liquid phase to the gas phase. There are two types of vaporization: evaporation and boiling. Evaporation occurs at temperatures below the boiling point, and occurs on the liquid's surface.
Changes in presure have very little effect on the volume of a liquid. Liquids are relatively incompressible because any increase in pressure can only slightly reduce the distance between the closely packed molecules. ... If the pressure above a liquid is decreased sufficiently, the liquid forms a gas.
when the gas becomes a liquid, however, the volume actually decreases precipitously at the liquefaction point. The volume decreases slightly once the substance is solid, but it never becomes zero. High pressure may also cause a gas to change phase to a liquid.
If you decrease both the pressure and temperature of a fixed amount of gas, any changes you observe will be in the volume of the gas. ... However, if you decrease the pressure by a greater degree than the decrease in temperature, the volume will increase.
Answer:
The phase change of matter depends upon the external pressure and temperature of the bulk of the substance , if there is no external pressure then there is no meaning of state , as then individual particles will have their own state rather than the state of the bulk
Dependence on temperature
If an isobaric system is considered , where the external pressure remains constant, lets say a an open beaker kept at sea level on earth then external pressure would always be 1 atm then obviously state change would happen spontaneously in the form of evaporation as there would be negligible condensation , to increase the rate of state change bubbles need to form which will only form if the individual particles inside of the bulk would have sufficient Kinetic energy as well as vapor pressure of its bulk . Increasing the temperature in this case guarantees both as vapor pressure increases with temperature . At the boiling point the molecules have enough Kinetic energy and vapor pressure to oppose the external pressure hence change of state happens vigorously with formation of bubble , even before boiling point was reached the rate of evaporation was increasing and state change was taking place but due to insufficient vapor pressure bubbles weren't forming
Dependence on pressure
Now lets consider an isothermal system where temperature remains the same
for example - an isothermal beaker where the temperature of the system remains same
Inside it a liquid is taken , it'll have some pressure which is equal to its vapor pressure
there's an equilibrium present in which rate of evaporation is equal to the rate of condensation as the beaker is closed by a movable piston
now if the pressure is decreased slowly by pulling the piston then external pressure due to the gas of the liquid over the liquid decreases that is P(external) decreases and even though the Kinetic energy of the particle of the liquid is same as the temperature is same , more and more particles begin to escape from the surface of the liquid and go in the vapor phase , so we decreased the external pressure which was equal to the vapor pressure slowly and we observed a phase change without changing the temperature
This phenomenon happened because the rate of condensation decreased slightly ,rate of evaporation remained the same and hence we observed an increase in vapor phase
Again the equilibrium would be achieved even after shifting the piston such that the pressure would be equal to the vapor pressure , which didn't change as temperature was constant the whole time
Now if you vigorously decreased the pressure by pulling the piston then the particles in the bulk despite having the same kinetic energy are able to form bubbles ( P(vapor) > P (ext) ) , thus phase change happens at a high rate
So you made the liquid boil by just decreasing the pressure
The equilibrium would be achieved again where the rate of evaporation is equal to the rate of condensation and external pressure is equal to the vapor pressure
