Is Matter Around Us Pure, Characteristics Pure and Impure Substances, Questions (For CBSE, ICSE, IAS, NET, NRA 2022)

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Pure and Impure Substances

  • To answers all these questions, as per the scientists, a substance is said to be pure if it is made up of only one kind of molecules or particles. Pure substances normally cannot be separated by simple physical methods and are largely classified as elements and compounds. An element consists of only one type of particles which can be atoms or molecules. Likewise, compounds can also be pure substances when they contain two or more elements which are combined in a fixed proportion by weight. In addition, pure compounds can be easily decomposed into separate elements with the help of suitable chemical methods.
  • A substance that is composed of different kind of elements or molecules then that substance is said to be impure. These types of substance are often referred to as mixture. Mixtures are further said to be either homogenous or heterogeneous. Mixtures are mostly made pure by the use of different types of separation techniques.

Characteristics of Pure Substance

  • They are perfectly homogeneous in nature.
  • They are made up of only one kind of atoms or molecules.
  • They have a fixed composition.
  • It has fixed density, melting point and boiling point etc.

Characteristics of Impure Substance

  • It does not have any specific properties; the properties of the mixture are a result of the average properties of all the constituents.
  • It is formed as a result of a physical change.
  • They have a variable composition.
  • The mixtures are either heterogeneous or homogeneous mixture in nature.

Questions

Are Matter Around Us Pure?

Answer:

  • A pure substance consists of a single type of particles. In other words, a substance is a pure single form of matter.
  • As we look around, we can see that most of the matter around us exist as mixtures of two or more pure components, for example, sea water, minerals, soil etc.

What is Meant by a Pure Substance?

Answer:

A substance that has a fixed chemical composition throughout is called a pure substance such as water, air, and nitrogen. A pure substance does not have to be of a single element or compound.

What Are Pure Substances Give Three Examples?

Answer:

  • Examples of pure substances include tin, sulfur, diamond, water, pure sugar (sucrose) , table salt (sodium chloride) and baking soda (sodium bicarbonate) .
  • Crystals, in general, are pure substances. Tin, sulfur, and diamond are examples of pure substances that are chemical elements.

Which is the Best Example of a Pure Substance?

Answer:

The best examples of pure substances are pure elements, molecules, and compounds:

  • Hydrogen gas.
  • Gold metal.
  • Sugar (sucrose)
  • Baking soda (sodium bicarbonate)
  • Ammonia.
  • Diamond.
  • Copper wire.
  • Silicon chip.

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