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

We all know that matter exists in three different physical states. All matter exists in solid, liquid or gaseous states. But as students go up to higher classes, they will learn that there are other states where matter exists in more sophisticated forms. Still, most of the substances in our daily life exist in the three basic physical states.

The Solid State

A solid-state the greater is characterized by strong bonds of attraction between its elementary particles. They have a fixed density and shape. They are the most stable state of any substance. They are rigid and relatively strong.

The liquid State

The liquid state is characterized by its appearance. It is not rigid and has relatively low intermolecular attraction between its particles. Liquids do not have a specific shape and take the shape of any container that they are placed in. They have a fixed density, unlike gasses.

The Gaseous State

The gaseous state is the most volatile physical form of an object. The particles are in constant motion and possess a lot of kinetic energy. They have large interatomic spaces and are less stable. They do not have any definite shape or density. They have low intermolecular and interatomic interaction due to their kinetic energy.

Even when this is the case, no substance permanently remains in its basic physical state. This is because of external forces acting on it. Every substance in the world is influenced by both internal and external forces. So they undergo a constant physical transformation. These transformations are facilitated by different processes that can be either spontaneous or forced. Some of them are boiling, melting, evaporation, sublimation, fusion, condensation etc. 

All these processes involve some amount of energy. Energy is either consumed or released during physical transformation. Energy consuming processes are called endothermic processes while energy releasing processes are called exothermic processes. Whether energy is used or released is determined by the nature of intermolecular or interatomic forces acting upon different substances. Solids have the greatest interatomic interaction, so any process that starts with the solid-state consumes energy since these strong bonds need to be broken. The reverse processes that result in the solid-state will be exothermic. Similar principles apply for liquids and gasses and their energy utilization is determined by the extent of atom-atom interaction and the energy these particles possess.

Have you tried making Maggie on the top of the mountain? not yet? Now, cooking Maggie at the top of the mountain will  test your knowledge of chemistry as well as your cooking skills. So before you reach the top of the mountain and test your cooking skills, uncover the chemistry behind it and improve your experience. 

Water boils at 100 ° C on the surface of the sea, but water in highlands such as mountain peaks begins to boil at low temperatures. When you try to cook Maggie at the top of the mountain,  the  water boils at a low temperature and evaporates quickly. Because of this, Maggie remains half cooked and needs more water to cook it well. Therefore, it takes  time to cook Maggie in the mountains. 

In this article, to get a clear understanding of the concept, we will first elaborate on vaporization and boiling, and then explain the differences between them. 

What is boiling? 

Boiling means that the liquid evaporates rapidly when  heated to the boiling point. For example, when  water is heated to 100 ° C on the surface of the sea, the water begins to boil and turns into steam. Boiling water is used to kill and soften the microorganism that are present there. It is also used in a variety of cooking methods.

In the boiling process, the vapor pressure of the liquid can overcome atmospheric pressure. That’s why bubbles can form and rise upwards in boiling. 

 

What is Boiling Point? 

• The boiling point of a substance is the temperature at which the vapor pressure of the liquid corresponds to the pressure surrounding the liquid and the liquid turns into vapor. The boiling point of a substance depends on the ambient pressure. High-pressure liquids have a high boiling point, and low-pressure liquids have a low boiling point. For example, at sea level, it boils at 100 ° C, but in the highlands where atmospheric pressure is low, water boils at temperatures below 100. ° C. 

•  factors affecting boiling point 

•  The following factors affect the boiling point- 

•  Atmospheric pressure-The boiling point of a substance changes depending on the ambient pressure. The higher the atmospheric pressure, the more energy is needed to break the bonds between the particles, and the boiling point rises. Therefore, high pressure raises the boiling point and low pressure lowers the boiling point. 

•  Impurities-The boiling point of a compound is used as a reference for its pure form. For example, pure water boils at 100 ° C, while water containing various other substances and dirty water boils at a higher temperature.

•  Thus, impurities in a pure substance elevate the boiling point. 

What is Evaporation?  

Take a beaker and put water in it. Then place this mug on the flame and continue heating. After a while, you will notice that the water begins to boil and turns into steam. This phenomenon is called evaporation. Did you notice now that when a glass of water falls to the floor and no one wipes it off, it dries after a while? Wet clothing will dry out after a while. Do you know how to do it? This means that they have different amounts of kinetic energy at different temperatures, as we know that particles of matter are always moving and  never resting. Even in the case of liquids, a small portion of the particles on the surface with high kinetic energy can be converted into vapors away from the gravitational pull of other particles. This phenomenon of converting a liquid into vapor at any temperature below its boiling point is known as evaporation.

Factors Affecting Evaporation

Following factors affect the rate of evaporation –

• Surface Area – Evaporation is a surface phenomenon. As the surface area increases, so does the rate of evaporation. For example, distribute clothing and let it dry faster. The relationship between evaporation rate  and surface area can be written as 

evaporation rate ∝ surface area. 

• Temperature-Evaporation rate  increases at higher temperatures. As with the rise in temperature, more particles receive enough kinetic energy to change to a vapor state. For example, wet clothing dries quickly in the sun. The relationship between evaporation rate  and temperature can be written as:

Rate of Evaporation ∝ Temperature 

• Humidity – Humidity is the amount of water vapor present in the air. Air cannot hold more than a definite amount of water vapor at a given temperature. If the amount of water in the air is already high or maximum, the rate of evaporation decreases. Relation between rate of evaporation and surface area can be written as –

Rate of Evaporation  ∝ 1∕ Humidity

• Wind Speed – With the increase in wind speed, the particles of water vapor move away from the wind, decreasing the amount of water vapor in the surrounding area. Thus, an increase in wind speed increases the rate of evaporation as well. For example, clothes dry faster on a windy day. The Relation between rate of evaporation and surface area can be written as –

Rate of Evaporation ∝ Wind Speed 

Differences Between Evaporation and Boiling 

This ends our coverage on the Difference between evaporation and boiling point. We hope you enjoyed learning and were absolutely able to grasp the concepts. We hope after reading this article you will be able to answer questions related to this topic. If you are someone who is  looking for solutions to NCERT Textbook problems based on this topic, then log on to the website or download Learning App. By doing so, you will be able to access free PDFs of NCERT Solutions as well as Revision notes, Mock Tests and much more.