Difference Between Physical and Chemical Change - Definition, Characteristics, Examples, FAQs

Physical Change

Physical transformation or change is a result in which a substance's physical qualities, such as shape, size, quantity, appearance, colour, state (i.e., solid, liquid, gas), and so on, change without affecting its molecular composition. These changes are inherently unstable, but they can be reversed with basic physical techniques. The same component or combination exists before or after the alteration, i.e. the object's fundamental physical appearance is preserved. Examples of physical changes include wax melting, glucose dissolving in water, water bubbling, wood cutting, paper crumpling, and so on.

Chemical Change

Chemical change is explained as the method of rearranging or combining the molecules of one or even more substances to generate a new component. When a substance undergoes chemical transformation, its molecular character changes, and this is transformed into a new substance with a specific chemical structure. The development of energy, the formation of bubbles, and temperature variations are all examples of chemical change.

Alternatively, chemical change is called as a chemical reaction, in which the chemicals involved are referred to as reactants, as well as the reaction's outcome is referred to as a product. Because of the creation of the entire product, energy change is one of the characteristics of a chemical change. It is impossible to reverse the chemical change once it has occurred. For example, bleaching a stain, combining vinegar and baking soda, and so forth.

Common Physical Changes

1. Texture:

A physical alteration can modify the smoothness of a substance. A piece of wood that has been sanded, oiled, and polished, for example, will have a very different appearance than it had when it was rough.

2. Colour:

A substance's colour changing isn't always an indication of a chemical change. Changing the colour of a metal, for example, has no effect on its physical qualities. A colour change, on the other hand, is frequently an indication that a chemical reaction is taking place. The nature of the metallic component is not changed by painting the metal car whereas the physical appearance is altered.

3. Temperature:

Even though we cannot see change in temperature, it is a physiological response unless a change of condition occurs.

4. Shape:

An entity's shape can be modified while the object's molecular structure remains unchanged.

5. Change of state:

A physical change occurs when a substance changes its state. A multitude of physical qualities, such as viscosity and form, are changing in this scenario. When ice melts into water, it loses its solid form and becomes a viscous fluid.The common physical changes of state are:

Related Topics

• Physical Change Chemical Change
• Laws of Chemical Combination for Elements and Compounds
• Chemical Equation
• Example Chemical Change

Common Chemical Changes

1. Change in Temperature

Variation in temperature is a major characteristic of a chemical change.

2. Change in colour:

Another sign that a chemical reaction is currently happening is a change in colour. For instance, observing the rusting of metal over time will reveal that the metal has changed colour and glowed yellow. This colour shift is the result of a chemical process.

3. Odor development:

A chemical reaction occurs when two or more chemicals or components are combined, and a fragrance or odor is produced. A chemical reaction has occurred when an egg begins to smell (a rotting egg, for example). A chemical decomposition has resulted in this.

4. Formation of precipitate:

One of the most common signals that a chemical reaction is taking place is the emergence of a precipitate. A precipitate is a substance that develops inside another solid or within a solution.

Characteristics of Physical Change

The properties of physical change have three characteristics:

1. There is no formation of a new material.
2. The modifications are recoverable.
3. Both the product and the reactant have the same physical characteristics.

Characteristics of Chemical Change

Properties of chemical change have four major characteristics:

1. A chemical reaction results in the formation of a new material.
2. The alterations are long-term.
3. The change is usually irreversible.
4. It also entails the absorption or release of energy, such as heat or light.

Difference Between Physical and Chemical Change

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Some Solved Questions

Question 1: Which of the following is a chemical change?

A. Melting of ice
B. Dissolving sugar in water
C. Rusting of iron
D. Breaking of glass

Solution:
Rusting of iron forms a new substance (iron oxide), hence it is a chemical change.

Hence, the correct answer is option (C)

Question 2: Which statement is true for a physical change?

A. A new substance is formed
B. Chemical bonds are broken
C. Change is usually reversible
D. A Large amount of energy is absorbed

Solution:
Physical changes are generally reversible and do not involve the formation of new substances.

Hence, the correct answer is option (C)

Question 3: Which of the following processes involves both physical and chemical changes?

A. Melting of wax
B. Burning of a candle
C. Sublimation of iodine
D. Crushing of chalk

Solution:
Burning of a candle involves melting (physical) and combustion (chemical).

Hence, the correct answer is option (B)

Question 4: Which of the following is a physical change?

A. Photosynthesis
B. Fermentation
C. Evaporation of water
D. Digestion of food

Solution:
Evaporation changes only the physical state, not the chemical composition.

Hence, the correct answer is option (C)