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Physical Change and Chemical Change: Explanation with Examples - Testbook
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Some Basic Concepts of Chemistry
Defining Physical Change
Aspects like shape, size, color, and the state of a substance are called physical properties. These properties are influenced by physical changes.
For instance, when water evaporates into steam, it's a change in the physical state from liquid to gas. If we condense the steam, it turns back into water, demonstrating that this is a reversible process. Importantly, no new substance is created during this physical change.
Defining Chemical Change
A chemical change is a process that results in the formation of one or more new substances.
For example, when an apple is cut and left exposed to air, it turns brown. This is a new substance being formed due to the reaction with oxygen, causing the apple's color to change. Therefore, the browning of an apple is a chemical change.
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The Rusting of Iron
Rusting occurs when objects made of iron come into contact with oxygen and moisture. Rusting erodes a layer of material from the surface, weakening the object. Rusting is categorized as a chemical change.
The chemical reaction occurring during rusting is demonstrated below.
Rusting is undesired, and measures are taken to prevent it. One common method is galvanization, which involves coating iron with zinc. This process is frequently used in the manufacturing of water pipes.
The Process of Crystallization
Crystallization is a physical process in which large crystals of a pure substance are obtained from its solution. It's an example of a physical change.
Frequently Asked Questions
What are physical and chemical changes?
A chemical transition is the result of a chemical reaction, and a physical change occurs where the structure of matter changes but not the chemical identity. Examples of chemical transformations include fire, frying, rusting, and rotting. Examples of physical changes are to simmer and freeze.
What defines a chemical change?
Chemical reactions requiring the rearrangement of atoms of one or more compounds and the modification of their chemical properties or structure resulting in the creation of at least one new substance: iron rust is a chemical alteration.
Is Melting zinc a chemical change?
A chemical reaction is a mechanism that happens by converting one or more compounds into one or more other compounds. No chemical reaction is registered. However, if the mixture absorbs energy in the form of heat, the zinc may react chemically with the sulphur to form the compound zinc sulphide (ZnS).
Which process is a chemical change?
Material modifications arise as a substance becomes a new material, called chemical synthesis or, similarly, chemical decomposition into two or three distinct compounds, combined with another. These mechanisms are called chemical reactions, and they are usually not reversible or by additional chemical reactions.
What is the importance of chemical change?
Chemical processes allow one to understand matter’s properties. We can learn its chemical properties by observing the way a sample interacts with another matter. These properties may be used to classify an unknown specimen or to predict how different kinds of matter may react with each other.