Mixtures And Solutions

1       (1) Mixtures-

·      Mixtures are constituted by more than one kind of pure form of matter.

·      Mixtures contains more than one pure substance.

Types of mixtures-

·       There are two types of mixtures.

(a)  Homogeneous- A Mixture which have uniform composition is called homogeneous mixtures.

Examples- Sugar in water, Salt in water, Water in alcohol etc.

(b) Heterogeneous Mixture- A Mixtures which have non uniform composition is called Heterogeneous mixture.

Examples- Sand and Salt, Sugar and Salt, Oil and Water etc

(2) Solution-

A Solution is a homogeneous mixture of two or more substance.

Examples- Lemonade, Soda water etc

v Alloys- Alloys are mixture of two or more metals, or a metal and non-metal and cannot be separated into their component by physical methods. But still an alloy is considered as a mixture because it shows the properties of its constituents and can have variable composition. For example, brass is a mixture of approx. 30% Zinc and 70% Copper.

Ø A Solution has a Solvent and Solute as its components.

v Solvent- The Component of the solution that dissolves the other component in it is called the Solvent.

v Solute- The Component of the solution that dissolved in the solvent is called Solute.

Examples of solvent and Solute are given below-

1.       A Solution of sugar in water is a solid in liquid solution. In this Solution sugar is in the solute and water is in solvent.
2.     Aerated drink like soda water etc are gas in liquid solution. These contains carbon dioxide gas as solute and water (liquid) in the solvent

Properties of Solution

1.       A Solution is a homogeneous mixture.
2.      The Particles of solution are smaller than 1nm (10^-9 )
3.        Because of very small particle size, they don’t scatter a beam of light passing through the solution. So, the path of light is not visible in solution.
4.   The Solute particle cannot be separated from the mixture by process of filtration when undisturbed. That is, a solution is stable.

Concentration of a Solution 

·      The Concentration of the solution is the amount (Mass or Volume) of the solute present in a given amount (mass or volume) of the solution.

v  There are various methods to express the concentration of a solution, Some of them are given below-

•  Mass by mass percentage of a solution =  (Mass of solute)/(Mass of Solution)  ×100
• Mass by volume percentage of a solution = (Mass of Solute )/(Volume of Solution)×100
• Volume by volume percentage of a solution=(Volume of Solute )/(Volume of Solution)×100

Suspension –

·      Non-Homogeneous system in which solids are dispersed in liquids are called Suspensions.

·      A Suspension is a heterogeneous mixture in which the solute particle do not dissolve but remain suspended throughout the bulk of the medium.

·      Particle of a suspension are visible to the naked eye

Properties of the suspension

       I.          Suspension is a heterogeneous mixture.

    II.          The particles of the suspension can be seen by naked eye.

 III.          The particles of a suspension scatter a beam of light passing through it and make its path visible.

 IV.          The solute particles settle down when a suspension is left undisturbed, that is a suspension is unstable.

Colloidal solution

·      Colloidal solution is a mixture in which the particles are regularly suspended in fluid. It can be occurred in any of the three key states of matter like Solid, liquid and Gas.

·      It is a heterogeneous mixture.

Properties of Colloid

       I.          The colloid is a heterogeneous mixture.

    II.          The size of particle of a colloid is too small to be individually seen by naked eye.

 III.          Colloid are big enough to scatter beam of light passing  through it and make its path visible.

 IV.          They don’t settle down when left undisturbed. That is a colloid is quite stable.

Pure substance

·      It is defined as substances that are made of only one type of atom or molecule. The purity of a substance is the measure of the extend to which a given substance pure.

Types of Pure Substance

On the basis of their chemical composition, substances can be classified in two parts.

·       Elements- Robert Boyle was the first scientist who use the term Element in 1661.

                Elements is the purest part of substance. Which can not be broken down into simpler substance by chemical reactions.

Elements can divide into metal, Non-metal and Metalloids.

(1)  Metal- Metals usually show some or all of the following properties.

(a)  They have a lustre(shine)

(b)  They have silvery grey or golden yellow colour.

(c)  They conduct heat and electricity.

(d)  They are ductile

(e)  They are malleable.

Examples- Gold, Silver, Copper, Iron etc

           (2) Non-Metal- Non-Metal have following properties-

a.     They display a variety of colours.

b.    They are poor conductors of heat and electricity.

c.     They are not lustrous, Sonorous or meable.

Examples – hydrogen, oxygen,iodine,carbon,chlorine

            (3) Metalloids- Some elements have intermediate properties between those of mental and Non-Metals are called Metalloids.

Examples-Boron, Silicon, Germanium etc.

Compounds-

·      A compound is a substance composed of two or more elements.

Matter in our Surroundings

Matter in our Surroundings

Meaning of Matter in science –

Ø Everything in the universe is made up of material, which are called “Matter”

Matter is made up of small particles.

Examples-Air, Foods, Stone, clouds, Animals, Water, Evan a particles of sand etc

            Classification of Matter based on their physical properties-

(1)- Physical Nature of Matter – Matter is made up of particles. the particles of matter are very small. they are small beyond our imagination!!!

(2)-Characterises of particles of Matter -   Particles of Matter have space between them, particles of matter are continuously moving. Particle of matter attract each other.

(3) States of Matter – Matter around us exists in three different states. i.e. Solid, Liquid, Gas.

(a) Solid state- Solid matter are those Matter which have definite shape, size and volumes.

Examples- Pen, Book, Needles, Board, Bench etc

(b) Liquid state- Liquid Matter are those Matter which have fixed volume. Liquid Matter do not have fixed shape.

Examples- Water, Cooking oil, Milk, Juice, Cold drink etc

(C) The Gaseous State- The LPG, CNG (Compressed Natural Gas) , Oxygen etc , are the examples of Matter in Gaseous State. The Gaseous Matter are highly compressible as compared to Solid and Liquids Matter. In the Gaseous state, The Particle move about randomly at high speed.

(4) Can Matter Change its State?

(a) Due to effect of change of temperature- On increasing the temperature of solids, the Kinetic energy of the particles increases. Due to increase in Kinetic energy, the particle start vibrating with greater speed. The Energy supplied by heat overcomes the forces of attraction between the particles. The Particles have their fixed position and start moving more freely. A Stage is reached when the solid melts and is converted to a Liquid. The Minimum temperature at which a solid melt to become a liquid at the atmospheric pressure is called its melting point.

v Melting point of ice is 273.15K

v The Process of Melting , That is change of solid state into liquid state is known as Fusion.

v Latent Heat of Fusion- The Amount of Heat energy that is required to change 1 KG of solid into liquid at atmospheric pressure at its melting point is known as

(5) Evaporation- We know that particles of matter are always moving and are never at rest. At a given temperature in any gas, liquid, or solid, there are particles with different amount of kinetic energy. In the case of Liquids, a small fraction of particles at the surface having higher kinetic energy, is able to break away from the forces of attraction of the other particles and gets converted in Vapour. This Phenomenon of change of a liquid into vapours at any temperature below its boiling point is called Evaporation.

v The rate of evaporation increases with, an increase of surface, Temperature, wind speed etc. and also increases with the decrease of humidity.