Dhristi JEE 2022-24

What is Vaporization?

Vaporization can be defined as the method in which the state of the liquid transforms into the state of the vapor. The kinetic energy of the molecules increases as a result of an increase in temperature. The force of attraction between the molecules decreases as a result of the rise in kinetic energy. As a consequence, in the form of vapors, they escape into the vicinity. This approach requires heat energy.

 

Factors affecting the Rate of Vaporization

  • The concentration of an evaporating material in the air 

  • Air Rate of Flow - This is partly connected to the above concentration points. If 'fresh' air (i.e. air that is not already filled with a substance or other substances) is continuously flowing over the substance, the concentration of the substance in the air is less likely to increase with time, thus facilitating faster evaporation. This is the effect of decreasing the boundary layer at the evaporation surface with the velocity of flow, decreasing the distance of diffusion in the stagnant layer.

  • The amount of minerals in the liquid that have been dissolved 

  • Intermolecular Forces - The greater the forces in the liquid state that hold the molecules together, the more energy one has to get to escape. This is described by the vaporization enthalpy. 

  • Pressure - When there is less effort on the surface to prevent the molecules from launching themselves, evaporation occurs faster. 

  • Area Surface - As there are more surface molecules per unit of volume that are theoretically able to escape, a material that has a greater surface area can evaporate quicker. 

  • The Substance's Temperature- The higher the temperature of the material, the greater the surface kinetic energy of the molecules, and the faster the rate of their evaporation.

 

Two Modes of Vaporization Exist: Evaporation and boiling. Evaporation is a surface phenomenon while boiling is a bulk phenomenon.

 

Evaporation

Evaporation is a phase transition from the liquid phase to a vapor (substance state below critical temperature) which occurs at a given pressure at temperatures below the boiling temperature. On the surface, evaporation occurs. Evaporation occurs only when a substance's partial vapor pressure is less than the equilibrium vapor pressure. For example, vapor pumped out of a solution would eventually leave behind a cryogenic liquid due to continuously decreasing pressures.

 

Applications

  • Many printing and coating processes include industrial applications; recovering salts from solutions; and drying a range of materials such as lumber, paper, fabric and chemicals. 

  • A typical preparatory step for many laboratory tests, such as spectroscopy and chromatography, is the use of evaporation to dry or concentrate samples. Rotary evaporators and centrifugal evaporators are systems used for this purpose. 

  • Even if the ambient temperature is below the boiling point of water, when clothes are hanging on a laundry line, water evaporates. Factors such as low humidity, heat (from the sun), and wind accelerate this. 

 

Boiling

Boiling is  a phase change from the liquid phase to the gas phase, but boiling is the formation of vapor below the liquid surface as bubbles of vapor. Boiling takes place when the substance's equilibrium vapor pressure is greater than or equal to the ambient pressure. The boiling temperature, or boiling point, is the temperature at which boiling occurs. The boiling point varies with the environment's pressure.

 

Applications 

  • Air Conditioning and Refrigeration - By compressing a gas so that it becomes liquid and then allowing it to boil, most forms of refrigeration and some kind of air conditioning function. This absorbs heat from the atmosphere to cool the refrigerator or freezer or to cool the air entering a house. Propane, ammonia, carbon dioxide or nitrogen are among the usual liquids. 

  • To Make Potable Water - As a method of disinfecting water, it is the oldest and most efficient way to bring it to its boiling point at 100 ° C (212 ° F), because it does not affect the taste, it is effective despite pollutants or particles present in it, and is a single step process that removes most microbes responsible for causing intestinal disease.

  • In Cooking - Boiling is the technique of cooking food in boiling water or other liquids such as stock or milk that are water-based.

 

Examples of Vaporization

  • Industrially, salt is recovered by the vaporization process from sea-water. 

  • The process of vaporization allows wet clothes to dry up. 

  • The method is used for the isolation of the components of a mixture in many manufacturing processes.

 

Did You Know?

Sublimation is an endothermic process which occurs in its phase diagram at temperatures and pressures below the triple point of a substance, corresponding to the lowest pressure at which the substance can exist as a liquid. Deposition or sublimation, in which a substance passes directly from a gas to a solid level, is the reverse sublimation process. Sublimation has also been used as a generic term to describe a transition from solid to gas (sublimation) followed by a transition from gas to solid (deposition).


High Heat of Vaporization

The high heat of vaporization is defined as the heat required to convert 1 gram of liquid into the gaseous state. As the temperature rises, the hydrogen bonds present in the liquid water start to break. Water has the highest known heat of vaporization.  Whenever heat is provided to the water, molecules start getting dismissed and they vaporize. The surface molecules get cool and hence More kinetic energy is required to evaporate water and hence water has the highest heat of vaporization. 


Whenever a liquid in a closed container is heated, the liquid which is getting converted into a gaseous state, through evaporation is unable to escape. This process continues until there are as many molecules as the liquid state.  At this point, the vapor is said to be saturated vapor, and the pressure associated with it is saturated vapor pressure. 


Summary

  • Vaporization helps to get converted from liquid to a gaseous state.

  • There are two types of vaporization: boiling and evaporation.

  • Vaporization requires more energy as more effort is required to convert the liquid state into the gaseous state.

  • The graph of vaporization decreases with temperature and at a critical point called Critical temperature, it diminishes.

  • Condensation is the reverse process of vaporization.

  • Nils Wallerius was the first person to make some studies on evaporation and vaporization of liquids using some scientific methods.


Questions that can be asked in the Exam:

  1.  Explain the factors affecting vaporization.

  2.  What is the high heat of vaporization?

  3.  Differentiate between boiling and evaporation.

  4.  Differentiate between vaporization and boiling.

  5.  What is sublimation? Give an example.

  6. What is vaporization and explain the process.

  7. At what temperature water does not evaporate?

  8. Why does water record the highest heat of vaporization?

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FAQs (Frequently Asked Questions)

1. What's the difference between Vaporization and Evaporation? 

Vapourization is the phase that occurs during evaporation or sublimation.  Evaporation is a process that is nothing but a type of vaporization which occurs below the boiling point of the liquid. During vaporization solid-state gets converted into a liquid state and then into the gaseous state, whereas in evaporation the liquid state directly gets converted into a gaseous state. Vaporization is a fast process and evaporation is a slow process. In vaporization the entire water can turn into gas but whereas during evaporation only the surface water gets converted into gas. Vaporization requires less amount of energy and evaporation requires a higher amount of energy.

2. Why does Vaporization Occur? 

Vapourization is defined as the process of converting a solid or liquid substance into a gaseous state. Whenever the temperature of the solid or liquid substance is increased, the interaction between molecules also increases. This continuous motion between the molecules tends to break the bonds present between them, and when these bonds break, they get separated. This causes them to get vaporized or turn into a gaseous state. Vaporization can take place at any temperature. There are two types of vaporization: boiling and Evaporation. Vapourization power depends upon the intermolecular forces present between the molecules, and whenever the temperature is increased, the solid or liquid starts vaporizing and gets converted into a gaseous state. 

3. What is required for Water to Change from Solid to Liquid or Vapor?

For any substance to get converted from liquid to gaseous state heat of vaporization, temperature and pressure are required. With the help of this heat of vaporization, any substance 


gets converted from a liquid state to a gaseous state. Whenever a solid reaches its melting point, it will get converted into liquid, and if it reaches boiling point it will get converted into a gaseous state. So whenever solid will be heated at its melting point, it will get converted into liquid and when this liquid water is heated at its boiling point, liquid water will get converted into gaseous vapor. 

4. What is the difference between vaporization and boiling?

Vaporization is the process of converting solid or liquid into a gaseous state. Boiling is rapid vaporization that takes place due to heat supplied to any substance. The difference between vaporization and boiling is that vaporization can take place at any temperature whereas boiling of any liquid or solid requires a definite temperature known as boiling point.  This boiling point is defined for all the substances. During the boiling process, Bubbles are produced whereas in vaporization there are no bubbles formed. Boiling is a Fast process and vaporization is a slow process. Vaporization takes place only on the surface but boiling happens throughout the liquid 

5. What is vaporization used for?

Vaporization is the process where a solid or liquid gets converted into a gaseous state at any temperature. Vaporization is basically used to drain out moisture from the substance, leaving behind only the solid part. The most common technique of vaporization called evaporation is used in various daily life actions. Evaporation is used to obtain salt from seawater, is used to dry clothes, Ice cubes And perspiration in our body. Vaporization also helps the cloud to remain cool and provides moisture. In industries for the separation process, evaporation is used. In the food Industry, evaporation is also used to concentrate any foods such as noodles or To make condensed milk.

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