Changing States of Matter

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States of Matter and Changes of State

Have you ever wondered why ice turns into the liquid state after melting? Do you ever notice what happens when water boils? The answer to all such questions is straightforward: that is the changing states of matter. Whenever a substance absorbs energy or loses its energy, it changes its state. The reason behind such a change is due to the increase in kinetic energy. After absorbing the energy, the atoms or molecules in the substance start moving rapidly, and the increased kinetic energy drives the particles far away. 


What are the Three States of Matter?

There are generally three states of matter, namely; solid, liquid, and gas. In the solid-state, the molecules or particles are closely packed to each other, and hence they have a strong intermolecular force of attraction. In the liquid state, particles are quite separated from each other and hence have less force of attraction between them. However, in gases, particles are highly apart from each other and thus have the almost negligible force of attraction. 

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The diagram shows the effect of temperature on the states of matter and changes of state. 

Whenever there is a change in the pressure or temperature of a substance, changing states of matter occur. The effect of temperature on states of matter changing is directly proportional to the increase in interaction between the molecules present in the substance. When the temperature decreases, particles get a chance to relax into a more rigid structure. 


What is the Reason Behind Changing States of Matter?

Almost every substance undergoes a state change, whether it’s solid, liquid, or gas. It depends on the energy supplied or absorbed by the substance in which form they are changing. The changing states of matter are always physical and commonly include:

  • Sublimation

  • Melting

  • Freezing

  • Condensation

  • Deposition

  • Vaporization

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The diagram shows the processes that describe how can matter change its state from solid to liquid, solid to gas, liquid to gas, liquid to solid, gas to solid, and gas to liquid. 


What Changes Occur Between Solids and Liquids?

Melting: Any cold substance when brought to a warmer area absorbs energy. The energy absorbed by the colder substance facilitates them to overcome the strong intermolecular force of attraction. It enables them to rapidly move out of their fixed positions and, as a result, changes the state of matter. Due to an increase in temperature, any solid form starts melting. Similar to this concept, ice melts at higher temperatures and changes into a liquid state.  


Freezing: In the freezing, the transfer of heat is from the matter with higher temperatures to the substance at lower temperatures. The hot substance loses heat to the colder one, and the heat transfer continues until no external energy is available for the particles. It results in the close packing of particles and a strong force of attraction between them. Because of the decrease in temperature, there is a change of liquid state to solid-state. 


This solid to liquid process refers to freezing. Generally, water freezes into ice at a temperature of 0℃. Freezing means the solidification phase change of liquid state to solid due to cooling.


What Changes Occur Between Liquids and Gases?

Vaporization: The bubbles of the water vapour form when the water is boiling. It is because the water molecules get enough energy to overcome the intermolecular force of attraction, and as a result, water changes into a gaseous state. The temperature at which water or any liquid starts boiling refers to its boiling point. Generally, water starts heating when the temperature goes up to 100℃. At this temperature, water starts converting into vapours. The process of change of liquid form of water into a gas or vapour phase refers to vaporization. 


Condensation: When the evaporated vapours come in contact with cold substances, they start losing energy. As a result, the cold substances have not enough energy to overwhelm the force of attraction, and they form droplets of water liquid. Thus, when the temperature starts decreasing, the vapour starts changing its state: gas changing into liquid. The condensation process is just the reverse of the condensation process. 


What Changes Occur Between Solids and Gases?

Sublimation: It is the process in which the solid substance changes directly to gases. It generally happens when the solid substance absorbs energy to overcome the strong intermolecular forces of attraction between solid molecules. The reverse of this process is that; gas to solid process refers to deposition. One of the greatest examples related to the sublimation process is dry ice. Some other examples include the element iodine and high-quality coal.

FAQ (Frequently Asked Questions)

1. What is Needed to Change the State of Matter?

If you either add or take the heat away from a matter, it defines its changing state. Whenever you add heat to a matter, it starts melting. However, if you take the heat away, it starts solidifying. Adding and limitation of heat from the matter leads to change in the state due to the movement of particles. The atoms present in a matter always keep moving at a different speed. Heat adds speed to them.

2. What are the two Types of Changes that Occur in the Matter?

Usually, matter undergoes two main changes- physical and chemical change. In the physical alteration, there is no change in the identity of a matter. However, its state, size, and shape change. However, in case of chemical change, you cannot reverse it back or if it’s reversible under only certain conditions.