[Chemistry Class Notes] on Phase Changes Pdf for Exam

We know how it feels to finally get your hands on the ice cream which you made it all by yourself and put it in the freezer, so it turns into ice. This is one of the ways you are, indeed performing a phase change experiment. The phase change is happening all around us, from water being evaporated to form clouds to cloud showering rain. Everything we see around us is in the phase change or has completed its phase change. In addition to this, the phase change is one of the basic concepts of chemistry, but it works as the foundation of other complex concepts which you will study in higher classes. 

Properties On Which Phase Changes Are Dependent

The tea spreads out from the teabag when we immerse it in hot water in the same way the molecules that are restricted to a particular area during the phase will try every possible way to spread themselves. This is known as escaping tendency to understand the fundamentals of equilibrium and transformations for chemical reactions, and one needs to be familiar with these phase changes. 

The scientist has observed that even if the object is in a solid or liquid state, it will tend to escape into the gas phase also if there is absolutely nothing to make the change possible. 

To measure the escaping tendency of a given element one needs to calculate its vapour pressure which is a direct measure of the escaping tendency. 

The same thing happens when we keep the water outside it gets evaporated even if the temperature is not more than 25 degrees celsius. During the evaporation phase, some of the particles of water that are present in the air they too get condensed and become liquid, but the speed of this process is so slow that no water remains. In the end, these two-phase changes reach a point where both of them get stabilized, and that’s where we entered the equilibrium value.

The equilibrium value depends on the substance that you are using and the temperature around it. The other name of this property is equilibrium vapor pressure. 

We have on earth three phases of matter, and these are solid, liquid, and gas. In solid the particles of a given object are so tightly packed that they make the object look rigid and gives it a fixed shape that can’t change until some external force is used.

Secondly, we have a liquid the particles present in the liquid are not so tightly held as they were in the solid-state. As a result, we get to see the shape-shifting property of liquid. Also, having less force of attraction between the particles, some of the liquids are quite reactive and can quickly form compounds. Most of the compounds that form are present in the liquid state. Because gas state is too reactive and it is hard to get to the solid-state from the reaction. 

Gas particles are not held together in any way possible, as soon as you give them a little bit of space they expand in that region. Thus, they move around a lot and can quickly fill an entire area in no time. 

The boiling point of water is 100 degrees Celcius, and the freezing point of water is 0 degrees celsius. 

Describe All Different Types of Phase Changes

Given below is the list of all the different types of phase changes in physics and chemistry.

1. Sublimation 

Sublimation is the process where the matter changes its state from solid to gas without being converted into liquid in the first place. One of the examples of sublimation is the naphthalene balls that you use to keep your winters clothes packed and safe in summer. 

2. Deposition

The opposite of sublimation is deposition, here the matter is present in the gaseous state, and as the reaction occurs, it changes into soil state without being converted into a liquid which is the intermediate state. An example of this is hard to find because you need to have a sub-zero temperature to achieve it. But in higher altitude and south and north pole, we can see vapours of water being converted into solid ice without getting into their liquid state. 

3. Melting

When a matter changes its state from solid to liquid, for example, ice cubes, when taken out from the freezer, start to melt.

4. Boling

Boling of a matter occurs when it reaches a certain temperature, its a non-natural process and requires a high amount of heat. Boling water to kill bacteria inside it is also a non-natural process.

5. Freezing

When a matter changes from liquid to solid, when you put water in the freezer, and it converts into ice. 

6. Condensation

When a matter changes itself from the gaseous state to liquid state, water particles in the air get condensed when they come in contact with a cold water bottle.

7. Evaporation

Changing of liquid matter into a gaseous state. The water in the ocean evaporates to form clouds in the atmosphere.