Physical and Chemical Changes

Transformation is happening all the time, everywhere. Scientists have classified types of modifications in the same way that they have classified chemical elements. Changes can take two forms: physical and chemical. Change does not occur on its own. A transformation in a material is always accompanied by a cause. Ice, for example, does not melt by itself to produce water. To melt and transform into water, ice should be boiled. 

There are two different kinds of changes occurring in our environment: physical and chemical changes. Let’s compare and contrast them.

Definition of Physical and Chemical Change

A physical change is a change in a material’s physical qualities that is transient and reversible. It is a phenomenon where a substance’s physical qualities, such as form, size, quantity, appearance, colour, condition, and so on, alter without changing its chemical composition. The blazing of an electric bulb, the dissolution of iodine, the burning of wax, the dissolving of sulfur, and the evaporation process are all examples of physical changes.

To better understand, let’s look at how water changes as it boils or cools. Ice melts and water evaporates as the temperature rises. Water vapour starts to cool to produce water, and water freezes to make ice as it cools. This is a reversible transformation in which the shape of water changes when the circumstances are reversed. A similar change occurs in the condition when the wax and butter melt.

A chemical change is described as a procedure of rearranging or combining the atoms of one or even more materials to generate a new component. When a material undergoes a chemical change, its chemical characteristics shift and it is transformed into a new material with a distinct chemical structure.

To understand this phenomenon better, let us take the example of the conversion of milk to curd. When some amount of curd is added to the milk, the lactobacillus bacteria convert all the milk into curd, and this phenomenon cannot be reversed. This is an example of a chemical change because, here, milk’s molecular composition is changing. 

Difference in respect of Energy Absorption

In case of physical change, let us take the example of stretching a rubber band. When we stretch it, it uses the energy provided by the person to stretch it and when we release it the energy goes back out from the rubber band. However, this scenario does not take place in a chemical change. During a chemical change, energy is either required or expelled out from the reaction (the endothermic and exothermic processes). In the case of endothermic, energy is required to change chemical composition which gets utilised by the reaction. And in endothermic, the energy gets expelled out due to the generation of energy during the change.

Characteristics

Characteristics of physical changes

• There is change only in the physical qualities of any material
• There is no other material created.
• As we all know, physical changes are reversible, and thus can be reversed
• To separate two mixtures mostly a physical change is used
• The weight of the material does not get changed

Characteristics of a Chemical Change

• New chemicals will be created here Chemical alterations cannot be reversed by basic physical techniques
• The molecular formula of the material gets altered
• The bonds of the material get altered
• The formation of some new substance takes place in case of a chemical change
• The weight of the material or substance may change

 Conclusion

To sum up, Physical and Chemical changes are entirely different from each other. Physical change is the phenomenon of change in the properties of a substance such that the process can be reversed. And in the case of a chemical change, the process can not be reversed and entirely new substances are formed. Moreover, the atoms, molecules and bonds combining the atoms also get altered in case of physical change. Which does not happen in the case of physical change.