You all have witnessed the process of water boiling in your kitchen. You know when water is being heated at a high temperature for a longer time, the temperature of the water rises after which it starts boiling. But what happens when water boils and what are the bubbles in boiling water? You will find out where bubbles come from and lots more in this article.
1. What is the Boiling point of Water?
Everything changes its state at a particular temperature. Similarly, water also has a fixed temperature at which it transforms. It can take and store heat for up to 100 degrees celsius. It means that when the temperature of the water reaches 100 degrees, it starts boiling and that temperature is known as the boiling point. (See What is the Main Source of Water?)
2. What is the Effect of Heat?
When the container is heated, the temperature of the container starts rising and it also raises the temperature of the liquid inside. Now if the container is closed then the temperature rises more quickly than in an open container. The heat makes the water molecules shake vigorously and expand. As a result, they form droplets of water if the container is closed and if it is open then the water will convert to steam. So, what happens when water boils depends upon the temperature and heat that is being transferred to it. (See How does a Thermos Work?)
3. What is the Molecular Structure of Liquids?
The molecular arrangement of water is significantly loose and there is a very less intermolecular force of attraction between them. The molecules of water are not tightly packed in comparison to that of solid. It is the reason water can take any shape in which it is poured. Must read what are Examples of Elements in everyday life?
Water is also highly compressible, unlike solids. Liquids convert into a gaseous state when boiled above the boiling point because the loosely packed molecules expand and lose their durability. (See What is the NH4 Lewis Structure?)
4. What are the Bubbles in Boiling Water?
You all know about the molecular arrangement of liquids now. Because of this arrangement, their molecules shake easily when heated.
- When the water boils, the heat is transferred to the bottom making the water heat up faster than the water at the top.
- After this process, the molecules of water start to vibrate rapidly. This happens because of the heat being transferred to them. This dancing of molecules is what happens when water boils.
- Since the water at the bottom heats up rapidly it starts to convert into gas or vapor. But when that gas is not able to rise above as there is still water above, it rises and settles and this cycle keeps repeating. It is this process that forms the bubbles in boiling water.
- The bubbles are not water rather they are filled with air that is trying to rise. This rising steam is always trying to reach the surface and escape but instead, it is rising with water and converts into more bubbles. (Also read Why do atoms form chemical bonds?)
5. What happens when Boiling Water Reaches Evaporation?
As the bubbles reach the top of the surface, the water starts the process of transforming into steam or vapor. This process leads to what you call evaporation. During evaporation, the water starts boiling vigorously soon after which the change of state of matter takes place. You can observe water droplets in a closed container with boiling water but if you keep the container open the vapor is visible mixing with air. (See How is Dew Formed?)
6. When does Boiling Stop?
As long as there is water in the container which is boiling, the steam will continue to rise and become vapor. But if the stove or heat is turned off then the process of boiling and evaporation will stop. Must read how does a Water Wheel work?
Here is what happens when water boils, it changed its state from liquid to gas. Another example of water changing its state is when you pour water into the ice trays during summers. After keeping them in the freezer for some time, the water changes to ice (solid) undergoing another change of state. (Also read How Long does it take a Body to Decompose in Water?)