Combination of two or more substances called mixture.
Types of mixtures
Solution
Suspension
Colloidal solution
Solution
It is a homogenous mixture of two or more substances.
Properties of solution
It a homogenous mixture.
The size of particle is smaller than 1nm that cannot be seen with naked eyes.
The particles do not scatter the light.
The particles are very stable in the solution i.e they do not settle at the bottom.
The particles cannot be separated by any physical method of separation.
Concentration of solution
The concentration of solution can be found with the help of the following formulae:
i. Mass by Mass percentage
= (mass of solute / mass of solution) x 100
ii. Mass by volume percentage
= (mass of solute / volume of solution) x 100
iii. Volume by volume percentage
= (volume of solute / volume of solution) x 100
Suspension
It is a heterogeneous mixture of two or more substances.
Properties of suspension
It is a heterogeneous mixture of two or more substances.
The size of particle is more than 1nm that can be seen with naked eyes.
The particles are unstable that is they settle at the bottom if left undisturbed.
The particles scatter the beam of light.
The particles can be separated by filtration method.
Colloidal solution
Colloidal solution holds the property of both solution and suspension.
Properties of colloidal solution
It is a heterogeneous mixture of substances.
The size of particle is so small that it cannot be seen with naked eyes but are so big enough they can scatter the beam of light.
The particles are quite stable so they do not settle at the bottom when left undisturbed.
Separation of substances
Separation of dye from blue of black ink
The dye can be separated from blue or black ink with the help of evaporation.
Separation of cream from milk
Cream is separated from milk by centrifugation method. This method forces the denser particles to settle at the bottom and lighter particle to the top when it is spun rapidly.
Applications:
Used in blood test and urine test
Used to separate butter from cream
Used in washing machine to dry clothes by squeezing the water
Separation of two immiscible liquids
Two immiscible liquids can be separated with the help of a funnel.
Example: pour oil and water in a funnel and left it hanging for a few hours. After, that you can observe the water is settled at the bottom and the oil is floating on the top.
Applications:
Used to separate the mixture of oil and water
Used in extraction of iron from its ore.
Separation of mixture of salt and camphor
Mixture of salt and camphor can be separated by the method called sublimation. Camphor when heated, converts directly into gas without converting into liquid but the salt remains at the bottom. In this way, we can separate the two mixtures.
Separation of different color from a dye
Dye is made of multiple colors, which can be separated by chromatography.
Applications:
Used to separate the colors from dye
Used to separate pigment from natural colours
Used to separate drugs from blood
Separation of two miscible liquids
Two miscible liquids can be separated by the distillation method. In which the two miscible liquids have different boiling points.
Fractional distillation: It is used to separate the mixture of two or more miscible liquids that have 25K difference in their boiling point.
Separation of different gases from air
A series of process is used to separate different gases from air.
The air is compressed by passing it under pressure.
After that the hot air is cooled with the help of cold water running is a separate tube.
The air, after cooling, is stored in a column for fractional distillation where it is warmed slowly.
Different gases are separated at their own boiling point.
Separation of copper Sulphate from impure substance
Copper sulphate can be separated from impure substance by the method of crystallization. In this method, the mixture is heated and the solvent starts to evaporates. After the whole solvent is evaporated, the remaining solute is left to cool down, which after sometimes starts to form crystals.
Supply of water to our home
Several steps are used to purify the water before it reaches our home.
The water is first loaded in a sedimentation tank where it is left for a few hours and the sand is settled at the bottom.
After sedimentation, clear water is loaded into another tank where other impurities are sediment.
The water is then passed through a filtration tank, where fine impurities are filtered.
The clear water is then loaded into another tank for chlorination to kill the bacteria present in it.
In the last step, the water is supplied to our home.
Physical changes
Physical change is also called reversible change in which no new substances are formed and we can reverse it back to its original state. For example, the ice can be converted into water and vice versa.
Chemical changes
Chemical change is also called Irreversible change in which new substances are formed and we cannot reverse it back to its original state. For example, burning a paper will produce charcoal that cannot be used to get the paper back.
Pure substances
There are two pure substances
Elements
Compounds
Elements
It is a substance that cannot be divided into smaller particles in any chemical reactions. Elements are divided into three major categories:
Metals
Non-metals
Metalloids
Metals
Metals are lustrous
They can be drawn into thin wires and sheets.
They are good conductor of heat and electricity.
They are generally found in silver, gray, gold, or yellow colors.
They produces ringing sound
For example, steel and aluminum
Non-metals
Non-metals are dull
They cannot be drawn into thin wires and sheets
They are poor conductor of heat and electricity.
They are generally found in many colors.
For example, wood and plastic
Metalloids
These are substance that posses the property of both metals and non-metals. For example, boron and silicon.
Compounds
When two or more elements are chemically combined in fixed proportion, they are said to be compounds. For example, sodium chloride (NaCl)
