Question

notes on is mattr around us is pure of book s chand class 9th

Answer 1

IS MATTER AROUND US PURE

In our daily life whatever we see around is Matter. But is matter around us pure? A matter is defined as something which occupies space and has mass. Mass is a fundamental property which shows the amount of substance in an object.

How can we define the term purity? Many times we would have come across sentences like this water is pure or the milk used in making this tea is pure. Is this right? What is the basis for saying that a substance is pure? Can we say any substance is pure if it is smooth or soft or it is white? NO.

According to scientists, a substance is said to be pure if we take a substance and put it at a place and pick a particle from one corner and another particle from some random corner we get the identical particle despite the number of attempts made. In other words, a pure substance is made up of only one kind of elements or molecules. But if a substance is composed of different kind of elements or molecules then that substance is known as an impure substance. For example: When we were children, we would have played playpen with balls in which we have a large number of small balls. In this, we can have different colours of balls or all the balls can be of the same colour. If all the balls are of the same colour, then we can pick two balls from anywhere and it will be identical. This type of substance in which if we pick particles from any corner of the substance and it is same, then it is pure substance. But if the balls are of different colours in the playpen, then now if we pick balls from different corner they will not be identical always. This case in which if we pick particles from some random corners and are not identical then it is known as impure substance. The impure substance are often known as mixture.

Characteristics of pure substance:

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

Characteristics of impure substance:

It does not have any specific properties, the properties of mixture are result of the average of properties of all the constituents.It is formed as a result of physical change.They have variable composition.The mixtures are homogeneous as well as Heterogeneous Mixture in nature.

Answer 2

hy
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pure substance❓

made up of only kind of atoms or molecules

matter around us is of two types
__________________________

pure substance

mixture


mixture ❓

it contains two or more pure substances mixed together !!

pure substances are of two types.

elements ❓

which cannot be broken itno simpler substances by usual chemical method by supplying heat , light , energy !!

compounds ❓

it is a substance made up of two or more elements chemically combined in a fixed proportion

mixtures are of two types

homogenous ❓

in which substances are completely mixed and are indistinguishable from one another

heterogenous ❓

in which substances are not completely mixed with each other

alloys ❓

are homogenous mixtures of metals and nonmetals

solution ❓

a solution is homogeneous mixture

it consists

solute ❓

substance dissolved in solvent to make a solution

solvent ❓

which dissolves solute in it

properties of solution ❓

homogenous mixture.
particles are less than 1nm
they are stable
doesnot show tyndall effect

suspension ❓

in which solid substances are spread throughout the liquid without dissolving in it

properties ❓

heterogenous mixture.
are unstable
size if particles is 100nm

shows tyndall effect

colloids ❓

in which the size of solute particles is intermediate between those in true solution and suspension

properties❓

heterogenous mixture
particles size is intermediate between those in suspension and true solution
are unstable
shows tyndall effect

tyndall effect ❓

scattering of light by colloids

types of colloid ❓

sol

solid sol

aerosol

emulsion

foam

solid foam

gel

saturated solution ❓

a solution in which no more solute can be added at that temperature

unsaturated solution ❓

a solution in which more quantity of solute can be dissoved without raising its temperature

solubility ❓

maximum amount of solute which can be disdolved in 100 g of solvent at a specufic temperature

physical change ❓

in which no new substance is formed

its a temporary change

chemical change ❓

in which new substance is formed

its permanent change

filteration ❓

used to seperate insoluble substance from a liquid

crytallisation❓

process of cooling a hot concentrated solution to get the pure crystals

centrifugation ❓

un which suspended particles of a substance from a liquid un which mixture is rotated in a centrifuge machine

chromatography ❓

in which two or more solid substances present in solution in very small quantity is seperated

distillation❓

process in which heating the liquid to get vapours and cooling the vapours to get liquid back

evaporation ❓

is a surface phenomenon in which liquid is heated ti form vapours below its boiling point



hope helped❗