Is Matter Around Us Pure

Matter is anything that occupies the space and has certain mass. Matter can be impure or pure. Impure matter is a mixture of many pure substances. Mixture contains more than one kind of pure form of matter in which their constituents do not lose their identity. Mixtures are of two types; homogeneous and heterogeneous mixture. Homogeneous mixture is a mixture that has a uniform composition throughout. A solution is a type of homogeneous mixture. Alloys are homogeneous mixtures of two or more metals or a metal and non-metals. Solution is a homogeneous mixture of two or more substances. Heterogeneous mixture does not have uniform composition throughout.

Suspension is a type of heterogeneous mixture. Colloid is a type heterogeneous mixture with a dispersed phase and a dispersion medium. Their particle size is more than the 1 nanometer but particles cannot be seen with naked eye. These particles can scatter light. This effect is called Tyndall effect. Components of colloids can be separated by centrifugation. Saturated solution is a solution, which has dissolved the maximum solute at particular temperature and no more solute, can be dissolved in solution at that temperature. The amount of the solute present in solution at given temperature is called its solubility.

The components of a mixture can be separated by various physical methods that include: evaporation, sublimation, separating funnel method etc. Evaporation is used to separate a volatile component from a non-volatile component. Sublimation is used to separate a sublimable volatile component from a non-sublimable component. Separating funnel method is used to separate two immiscible liquids from their mixture. Chromatography is used to separate components that are soluble in same solvent. Paper Chromatography is used to analyse the presence of different colour in a dye or in a black ink. Distillation is used to separate two miscible components of a mixture that have different boiling points. Crystallisation is used to separate a pure solid from its solution. In this method, the saturated solution of a substance is allowed to evaporate slowly. The liquid evaporates leaving behind the pure solid.

Pure substances consist of only one component with definite physical and chemical properties and a definite composition. Pure substances can be classified into elements and compounds. Elements are pure substances, which are made up of only one kind of atom and cannot be further reduced to simpler substances. Compounds are the substances made up of more than two types of elements combined together chemically in definite proportion by weight. Substances undergo chemical changes during the formation of compounds whereas during the formation of mixture, substances undergo physical change only. In physical Change, no change occurs in the chemical nature and composition of the substances. During chemical changes, change occurs in the chemical nature and composition of the substances.

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  • Q1

    An example for a mixture of an element and a compound is

    Marks:1
    Answer:

    sulphur + carbon disulphide.

    Explanation:
    Sulphur is an element and carbon disulphide is a compound. Sugar and common salt are compounds having fixed compositions.Iron fillings are small pieces of iron.
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  • Q2

    The sky appears blue because of

    Marks:1
    Answer:

    Tyndall effect.

    Explanation:
    The scattering of light by colloidal particles, on passing through them is called Tyndall effect.
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  • Q3

    An example for a homogeneous mixture is

    Marks:1
    Answer:

    sugar + water.

    Explanation:
    The mixture has a uniform composition. It has no visible boundaries of separation between the various components. It is also called a solution.
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  • Q4

    The solvent which dissolves sulphur present in a mixture of sulphur and iron fillings is

    Marks:1
    Answer:

    carbon disulphide.

    Explanation:
    Sulphur is insoluble in water but soluble in carbon disulphide and to lesser extent in other polar organic solvents.
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  • Q5

    An example for heterogeneous mixture is

    Marks:1
    Answer:

    kerosene + water.

    Explanation:
    Sodium chloride, alum and sugar dissolve in water to form a homogeneous solution. When kerosene and water are mixed they form heterogeneous mixture because kerosene does not completely disolve in water.
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