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There are three states of matter: solid, liquid and gaseous which can interchange among themselves. Evaporation is a process that allows a matter to go from the liquid state to the gaseous phase while distillation is primarily a process of separation. Evaporation usually occurs when there is sufficient heat energy to break the intermolecular attractions and release the liquid molecules as gas molecules. Evaporation can occur naturally, but distillation requires some external factors to encourage it.
Read Also: Characteristics of Particles of Matter
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Key Takeaways: Evaporation, Distillation, liquid, gas, energy
What is Evaporation?
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Evaporation is a process that allows matter to change into its gaseous state from its liquid form without the participation of external factors. The matter doesn’t even have to reach its boiling point to undergo the change. Liquid molecules have intermolecular strength and with sufficient heat energy, they tend to dissociate, releasing the molecules as gas. The surface of the liquid is usually in close contact with the atmospheric air and the sunlight, which breaks down the molecular structure of the upper surface of the liquid and it is known that heat energy can be easily absorbed. The liquid does not even have to reach its boiling point for evaporation to happen. Due to evaporative cooling, energy removed from the vaporized liquid will reduce the liquid temperature, resulting in evaporative cooling of the liquid temperature. When the intermolecular strength of a liquid is high, it is less volatile and therefore it takes a longer time to evaporate. Liquids with low Intermolecular forces are highly volatile. Hydrogen bonds are usually stronger while Vanderwaal’s bonds are comparatively weaker. It can be noted that most nonpolar organic liquids are highly volatile. Overall, evaporation is a very slow process and the entire mechanism depends on the surface area of the liquid and air flow rate. With a high airflow right and surface area, evaporation’s rate increases.
Evaporation
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What is Distillation?
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Distillation is a process that refers to the separation or segregation of liquids using selective condensation as well as boiling. Distillation can always not be accurate and can also result in simply a higher concentration of the mixtures, therefore resulting in partial segregation. Distillation is basically a modern separation technique for liquids depending upon their boiling points. It basically exploits the different volatility levels in different liquids. Distillation can be termed as a physical phenomenon and not a chemical reaction. Different liquids dissolve or boil at different rates so distillation can be used to separate them. Boiling and condensing are two integral parts of distillation. The liquid is first heated and boiled at its boiling point. After that, the liquid evaporates and finally turns into a liquid phase with the aid of a condenser. There are different types of distillation known as simple distillation, fractional distillation and Steam distillation.
Distillation
Differences between Evaporation and Distillation
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The differences between evaporation and distillation are noted below:
| Evaporation | Distillation |
|---|---|
| Evaporation is a process through which liquid is turned into gas by adding heat to the liquid so that the molecules on the uppermost surface of the liquid turn into their gaseous phase. | Distillation is a process through which liquid vapour or steam is produced. The liquid is heated to produce the gaseous state of the liquid after which the obtained gas form is produced into its proper liquid form, free of impurities. |
| Evaporation is a very slow and gradual process. | Distillation is a very fast and rapid process. |
| Evaporation occurs mostly only on the surface. | Distillation occurs throughout the whole liquid. |
| Evaporation cannot be termed as a separation procedure. | Distillation can be termed as a separation technique. |
| The liquid evaporates below the boiling point. | The liquid evaporates exactly at the boiling point. |
| At boiling point, formation of liquid bubbles does not occur. | Formation of liquid bubbles occurs exactly at the boiling point. |
Check Important Differences Between Vaporization and Evaporation
Points to Remember
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Following are some important points:
- Evaporation is a process which allows a matter to go from the liquid state to the gaseous phase
- Distillation is a process of separating two liquids from a liquid mixture.
- In case of evaporation, a molecule absorbs enough energy to overcome the vapour pressure and escape to enter the surrounding air in the form of gas.
- Due to evaporative cooling, energy removed from the vapourized liquid will reduce the liquid temperature.
- Evaporation is useful in many household applications, especially drying clothes.
- Distillation is used to produce distilled beverages.
Sample Questions
Ques: Explain evaporation vs distillation. (3 Marks)
Ans: There are three major differences between evaporation and distillation. They are given below.
- Feature difference: Only the surface of the liquid gets affected in case of evaporation, while the entire liquid gets affected due to distillation.
- Duration difference: The process of evaporation is gradual and slow, but the process of distillation is rapid and quick.
- Boiling point difference: In case of evaporation, the liquid evaporates way below the boiling point while in case of distillation , the liquid evaporates exactly at the boiling point.
Ques: What are the different types of distillation methods? (3 Marks)
Ans: There are primarily three types of distillation: simple distillation, fractional distillation and steam distillation.
- Simple distillation: Simple distillation is a method which is used to segregate liquids having a very noticeable gap in their boiling points. In this process, the components of the liquid mixture are separated at their respective boiling points after which they change into vapour phase. After that, the vapour is condensed and collected which concludes the process of simple distillation.
- Fractional distillation: This process is used for liquids which have close boiling points. In this method, a fractionating column is used to separate two miscible liquids.
- Steam distillation: Steam distillation is a process which is mainly used for liquids which are immiscible with water. When such liquids compounds are mixed with steam, they tend to vapourize at a lower temperature than their boiling point.
Ques: What are some examples of distillation? (2 Marks)
Ans: Distillation is used in real life as well as laboratories for a lot of processes. They are mentioned below:
- Distillation is used highly in the beverage industry for alcohol fermentation.
- Salted water can be purified into water by using distillation.
- Fuel and gasoline are separated in crude oil through distillation.
- Air can be differentiated into its various components through distillation.
Ques: Which process is better: evaporation or distillation? (2 Marks)
Ans: Evaporation is not used for separation of liquid substances. It occurs naturally by changing its state of matter. Distillation is used to separate liquid components and it segregates them. Therefore, commercially and realistically, distillation is a better process.
Ques: What do evaporation and distillation have in common? (1 Mark)
Ans: Both evaporation and distillation depend on one fact: that the components of a liquid have variable boiling points.
Ques: What type of liquid evaporates first in distillation? (2 Marks)
Ans: The component with the lowest boiling point evaporates first while distilling, leaving the other solutes behind. Therefore, for distillation, the process takes place fast if the liquids in a solution have close boiling points as they will all start evaporation at around the same point of time. It can be said that the components with higher boiling points are the last to get evaporated.
Ques: How is evaporation different from drying? (2 Marks)
Ans: Drying is a process that is accomplished by imposing a difference in water activity between the food and its surroundings. Drying removes moisture from products so that microorganisms cannot grow on the very same products. Evaporation is used in the concentration of liquid foods. This makes water in the food reach the boiling point and escapes into the surroundings.
Ques: What factors affect distillation? (2 Marks)
Ans: The factors which affect distillation are:
- Water, vapour
- Condenser temperatures
- Dew point
- Water volume or water depth
- Vapour volume
- Geometry of enclosure
- Pressure
- Reflux conditions
- Column diameter
- Weather conditions
- Vapour flow conditions
Ques: What are the Applications of evaporation? (3 Marks)
Ans: There are many applications of evaporation and they are noted below:
- In laboratory processes like chromatography and spectroscopy, evaporation is used to concentrate or dry samples. These processes include centrifugal and rotary evaporators.
- Evaporation is useful in many household applications; when clothes are hanging outside in the sunlight the sun absorbs the water from the wet clothes. To clean places properly, evaporation is necessary.
- Traditional porous clay containers work through evaporation. They are used to cool and store water and other liquids.
- Coating and printing processes in the industry require evaporation.
- A variety of materials like paper, lumber, cloth and recovering salt from solutions, etc require evaporation.
- Evaporative coolers can cool buildings merely by blowing dry air over a filter saturated with water.
Ques: What are the Applications of distillation? (3 Marks)
Ans: There are many applications of distillation and they are noted below:
- Distilled beverages are formed through the process of distillation. Beverages with strong alcohol content can be separated from other fluids with fermentation products having higher commercial value.
- The vapour pressure of crude oil is lowered, which makes it safe through the process of distillation.
- Oil stabilisation is a kind of partial distillation in the petroleum industry. This function makes the oil safe for storage and transport.
- Desalination is a segment of distillation, and it is a traditional method for separating liquids.
- Air is separated into its components for industrial use, especially oxygen, nitrogen and argon. This process is also termed as cryogenic distillation.
- A lot of liquids are separated into their respective forms through distillation which helps in producing huge amounts of crude liquid products of chemical syntheses.
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