Physical Change-Characteristics

Have you ever noticed the change in shape or size of the moon, melting of an ice cube, burning of coal or wood, boiling of water, freezing of water, rusting, etc.? Ever thought about why and how these changes could occur? What is the scientific reason behind them? These changes are categorized under physical changes or chemical changes depending on the process involved during transformation. In the upcoming section, we will understand these changes in detail with examples.

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Before understanding the central concept, we must be familiarised with some essential terms related to it:

• Chemical reaction- Building or breaking interatomic bonds or transforming a substance is known as a chemical reaction.

• Physical change- A change that does not alter the substance fundamentally.

• Physical properties- Colour, odour, state of matter, density, solubility, weight, mass, size all are common examples of physical properties in daily life.

• Chemical change- The process that changes a substance into a completely different substance.

Physical change

As mentioned, weight, size,  density, colour, odour, height, volume, and appearance are all physical properties. Any change in a substance leading to alteration of these physical properties is called Physical change. The physical change only affects the physical appearance of a substance. That is, it does not affect the chemical properties of a substance.

For example, when ice is melted, it gets converted into liquid water. In this case, only the state of matter(water) is changed, not the chemical properties of water.

A substance undergoes a physical change when its compound creation is unaffected.

Characteristics of a physical change

Few properties help in distinguishing the physical changes from chemical changes. These are listed below:

1. No new substance formation: Whenever a substance undergoes a physical change, it never produces a new substance. For instance, consider a 100g of ice cube contained in a glass. When kept at room temperature for some time, 100g of water will be observed. This is because the state of matter has been converted from solid to liquid.

2. They are always reversible: As the name suggests, these changes can be easily reverted, for example, melting of ice, or we can say the liquid water can be again reformed into ice just by freezing it at the proper temperature, and solid ice can again be converted into liquid form just by the application of heat. So physical changes are always reversible.

3. No change in chemical properties of substance: the chemical properties of a substance remain unaffected regardless of physical change. For example, origami crafts made with paper only change the shape of the paper, not the chemical properties of paper.

4. Energy formation or evolution does not occur: In physical processes, energy is neither evolved nor absorbed. It means there is no production of any form of energy like heat, sound, chemicals etc. So, there is no liberation of energy.

5. Only physical parameters are changed: Physical properties mentioned in the above section are only subject to changes in such processes.

Characteristics of temporary physical change

Any change that is not forever lasting means not permanent is referred to as temporary change. Nearly all physical changes are temporary as they are reversible. A temporary physical change can be defined as a change where no new substance is formed, and also the chemical composition remains the same.

Features of temporary physical change-

• Are reversible

• No change in chemical composition

• only state if matter/substance is changed

Examples of physical changes

There are numerous daily life examples of physical changes. A few of them are categorized below:-

1. Physical changes observed in water-

• Melting of ice cube

• freezing if an ice cube

• evaporation of water while boiling

• conversion of water into steam while taking a hot shower

2. Physical changes that can be observed in the kitchen-

• Boiling of noodles to soften them.

• Crushing of waste wrappers.

• Using aluminium foil to cover something.

• Dissolving sugar in milk.

• Shaking up a bottle of ketchup before using.

• Freeze drying of fruits.

• Thawing meat

• Addition of milk in cereals.

• Melting chocolate

• melting ice cream

• whipping of cream

• Chopping of fruits

• mixing fruits and vegetables to make a salad.

• Addition of food colours into food.

• Sharpening knife

3. Outdoor examples of physical changes:-

• trimming a brush

• cutting hairs.

• dyeing you hairs

• crushing of carton box

• trimming nails

• making crafts with paper

• polishing gold or silver ornaments

• paper shredding

• knitting yarn into a cardigan

• melting a crayon

• cutting of a cloth

Some irreversible physical changes

Changes/deformation of a substance that cannot be reformed is known as irreversible change. Some of the physical changes are irreversible. A few of them are:

• Breaking of crockery

• mixing watercolours

• slicing of bread

• chopping of vegetables

• decrease in size of chalk after using it

• cracking an egg

• deformation of plastic toys

Conclusion

Everything around us is composed of matter. The term matter is vast and can denote even tiny minute particles present in our surroundings. The matter is composed of physical and chemical properties. This can undergo changes that can either be a physical change or can be a chemical change. Whenever a matter changes its state, such a type of change is termed physical change. In contrast, it is called a chemical change when the matter is subjected to changing its properties like a chemical formula, pH, etc., that completely transforms the substance into a new one. These changes can be further categorized as reversible and irreversible changes, depending upon their tendency to reform the initial substance.