Chemical and Physical Change, Chemical Change, Examples of Chemical Change, Question (For CBSE, ICSE, IAS, NET, NRA 2022)

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Title: Chemical and Physical Change

  • The sun rises, the night turns into a day, the seasons change, the leaves shed, flowers bloom and living beings grow! Every day, we see a number of changes happening around us. Change is inevitable. It takes place all the time and everywhere. However, changes differ from one another in a number of aspects. Some changes are fast, others are slow. Some of them are temporary, others are permanent.
  • Some are periodic, others are non-periodic. Some are natural, others are man-made. Some are reversible, others are irreversible. On the larger front, a change may be categorized into a chemical or a physical change depending on how the properties of a subject alter when it undergoes the change.

Physical Change

  • A substance is said to undergo a physical change when only the physical properties such as the shape, size, colour, state or appearance of the substance change. Its chemical composition remains intact. Some of the characteristics of a physical change are:
    • Temporary in nature.
    • Does not affect the internal structure of a substance, only the molecules are rearranged.
    • No new substance is formed.
    • Most of the physical changes are reversible. We can obtain the substance back even after the change.
  • Physical change examples are folding of a paper sheet, melting of wax, freezing and boiling water, melting of ice, condensation, vaporization, magnetizing a compass needle, dissolving sugar in water, etc.

What is Physical Change?

  • During the physical change, the arrangement of molecules is altered leading to change in state. No new products are formed, and the molecular composition remains totally the same. For example, the molecular composition of ice and water is not altered.
  • No energy changes occur when as a result of a physical change. The energy needed to bring a physical change is equal to the amount of energy required to reverse the change. There is no change in energy.
  • The changes are reversible and temporary. The reaction gets reversed if the cause of producing the change is removed. For example, water on freezing forms ice and ice on melting forms water.
  • During the physical change, the mass of the substance remains the same. Only energy is added or removed, and mass is not involved in a physical change.

Examples of Physical Change

Dissolution of sugar in water

  • Melting of ice
  • Freezing of water
  • Boiling of water
  • Melting of wax

Chemical Change

  • A substance is said to undergo a chemical change when the chemical properties of a substance alter. As a result, there is either formation or breaking of atomic bonds at the molecular level. Some of the characteristics of a chemical change are:
    • Permanent in nature.
    • Since the original composition of the substance changes, one or more new substances are formed.
    • Forms of energy, such as heat, light or electricity, may be emitted or absorbed.
    • A chemical change is generally irreversible. At least, it cannot be reversed by simple physical means.
  • Chemical change examples are burning of paper, burning of fuel, rusting of iron, the souring of milk, growth in a living being, cooking, digestion of food, burning of wood, etc.

What is Chemical Change?

  • The change in which the molecular composition is completely altered and a new product is formed is called a chemical change.
  • Chemical changes create a new product.
  • The changes in Chemical change are irreversible and permanent.
  • It reveals that chemical change cannot be reversed by changing or altering the experimental changes.
  • The mass of the substance is altered during a chemical change. Either the mass is added or removed.
  • During a chemical change, the energy changes occur. There is an energy difference in the breaking of old bonds in reactants and the formation of new bonds in products.
  • The reaction is called an exothermic reaction if the energy is released and as an endothermic reaction when the energy is absorbed.

Examples of Chemical Change

  • Burning of wood or paper
  • Burning of camphor
  • Souring of milk
  • Burning of candle
  • Digestion of food
  • There is a difference in energy during the breaking and making of bonds. The energy is given out to the surroundings if the energy required to break the bonds is higher than the energy required to make the bonds.
  • These changes or reactions are called exothermic. But the energy is absorbed from the environment when the energy needed to break the bond is lower than the energy required to make the bonds. Such reactions are called endothermic reactions.

Question

What is Difference between Chemical and Physical Change?

Answer:

Physical changes only change the appearance of a substance, not its chemical composition. Chemical changes cause a substance to change into an entirely substance with a new chemical formula. Chemical changes are also known as chemical reactions.

What Are 3 Differences between Physical and Chemical Changes?

Answer:

  • A chemical change is a permanent change. A Physical change affects only physical properties i.e.. , shape, size, etc.
  • Some examples of physical change are freezing of water, melting of wax, boiling of water, etc. A few examples of chemical change are digestion of food, burning of coal, rusting, etc.

What is the Physical Change?

Answer:

A physical change is a change to the physical as opposed to chemical properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape (volume and size) , color, texture, flexibility, density, and mass.

What Are Three Examples of Physical Changes?

Answer:

Examples of Physical Changes

  • Crushing a can.
  • Melting an ice cube.
  • Boiling water.
  • Mixing sand and water.
  • Breaking a glass.
  • Dissolving sugar and water.
  • Shredding paper.
  • Chopping wood.

Is Melting a Chemical Change?

Answer:

  • When you melt an ice cube () , you have a physical change because you add energy. You added enough energy to create a phase change from solid to liquid. Physical actions, such as changing temperature or pressure, can cause physical changes.
  • No chemical changes took place when you melted the ice.

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