[Chemistry Class Notes] on Difference Between Evaporation and Distillation Pdf for Exam

The matter has three phases such as solid, liquid, and gaseous phases. These phases are interconvertible in nature. However, they have some processes that they need to undergo in order to be able to interconvert into the other. Evaporation allows a phase change from the liquid state to the gas state. This process also takes place in the environment commonly around us.

The most common example is the heat of the sun evaporating the water in the sea or rivers into vapors. Unlike evaporation, the distillation process is not something that occurs naturally; it needs external energy to be provided in order to take place. In this process, there is the change of gases back to liquid. 

What are Evaporation and Distillation?

Evaporation is described as a type of vaporization method that occurs on the liquid’s surface as it changes into the gas phase. The gas that is surrounded must not be saturated with the evaporating substance. The liquid molecules transfer energy to each other when they collide, depending on how they collide. When a molecule available near the surface absorbs enough energy to overcome the vapor pressure, it will escape and enter into the surrounding air in the form of gas. When evaporation occurred, the energy which has been removed from the vaporized liquid will reduce the liquid temperature, resulting in evaporative cooling.

 

On average, only a fraction of the liquid molecules has enough heat energy to escape from the vaporized liquid. This evaporation will continue until an equilibrium is reached when the liquid evaporation becomes equal to its condensation. Throughout the enclosed environment, a liquid will be evaporated until the surrounding air is saturated.

 

Evaporation

Evaporation is a necessary component of the water cycle. Solar energy (sun) drives the evaporation of water from water resources such as lakes, oceans, soil moisture, and other sources of water. In hydrology, it is said that evaporation and transpiration (which involves evaporation within the plant stomata) are collectively termed evapotranspiration. Water evaporation takes place when the surface of the liquid gets exposed by allowing the molecules to escape and form water vapor. Then, this vapor can rise and then form clouds. The liquid will turn into vapor having sufficient energy.

 

Applications of Evaporation

• Industrial applications include most coating and printing processes. These include drying a variety of materials such as paper, lumber, cloth, and other chemicals, and recovering salts from solutions.

• The evaporation used to concentrate or dry samples is a common preparatory step for most laboratory analyses like chromatography and spectroscopy. These systems include centrifugal evaporators and rotary evaporators.

• If clothes are hanging on the laundry line, even though the ambient temperature falls below the water boiling point, water evaporates. This is accelerated by factors including heat from the sun, low humidity, and wind. Hot air is blown through the clothes in a clothes dryer, allowing water to evaporate rapidly.

• A traditional Indian porous clay container called Matki/Matka is used to cool and store water and other liquids.

• A traditional Spanish porous clay container called Botijo, designed to cool the contained water by the evaporation process.

• Evaporative coolers can cool a building significantly by merely blowing dry air over a filter saturated with water.

 

Distillation

The process of separating the substances or components from a liquid mixture by using selective condensation and boiling refers to distillation. Essentially, distillation can result in a partial separation or a complete separation (approximately pure components), that increases the concentration of the selected component present in the mixture. In the other case, the method exploits differences in the relative volatility of the mixture’s components. Considering industrial chemistry, distillation is a unit operation practically of universal importance. Still, it is a process of physical separation, not a chemical reaction.

 

Applications of Distillation

• The distillation of fermented products forms distilled beverages with a strong alcohol content or separates certain other fermentation products having commercial value.

• Distillation is a traditional and effective method of desalination.

• Oil stabilization is a kind of partial distillation in the petroleum industry, that lowers the vapor pressure of crude oil, making it safe, thereby for transport and storage, and reducing the atmospheric emissions of volatile hydrocarbons. In oil refineries midstream operations, fractional distillation is a primary operational class for converting crude oil into fuels and also chemical feedstocks.

• Cryogenic distillation tends to separate air into its components, notably oxygen, argon, and nitrogen for industrial use.

• Huge amounts of crude liquid products of chemical synthesis in the chemical industry are processed to separate them from the impurities, unreacted starting materials, or other products.

 

To discuss briefly, there is much difference between evaporation and distillation. A few of them are tabulated below.

 

Difference Between Evaporation and Distillation

 

From the above-tabulated difference between evaporation and distillation, it can conclude that the primary difference between them lies at the boiling point. Evaporation occurs below the liquid boiling point, whereas distillation occurs right at the boiling point. Both processes depend on certain factors that may be the same, but considering all the cases, they are vastly different.

 

Examples of the Evaporation process

The rain cycle is one of the most common examples of the evaporation process. This process involves two cycles where the first cycle involves evaporation of the water from water bodies and the second part of the cycle where the vapors condense to form the liquid. The colder the temperature tends to be, the faster the condensation that takes place.