Activity to Show Preparation of a Mixture

  • Take some Iron filings and Sulphur powder
  • Mix and crush them
  • Bring a magnet near the mixture
  • We see that Iron fillings get attracted to it

 

This means that it is a mixture as it still shows properties of Iron (to be attracted by a magnet)

Also, the mixture can be separated using physical methods like magnetic separation .

 

Activity to Show Preparation of a Compound

  • Take some iron filings and sulphur powder
  • Mix and crush them
  • We also heat the same till it is red hot
  • Then we let it cool for some time
  • Now we bring a magnet near it

 

The Iron fillings are no longer attracted to magnet

This is because now a compound has been formed which has completely different properties from its constituent elements

 

Also, any physical method of separation cannot be used to separate the two.

 

 

Difference between Mixture and Compounds

 

 

Mixture

Compounds

They are formed by mixing of 2 or more substances  

(these may be elements or compounds)

They are formed by reaction between 2 or more elements



A mixture has variable composition  

(Ratio of 2 or more substances may not be same )

A compound has fixed composition  

(Ratio of 2 or more substances is same)

A mixture shows properties of substances it is made up of (constituent substances)

Properties of compound are different from its Elements

Different Elements of Mixture can be separated by Physical methods




Different Elements of a compound cannot be separated by Physical Methods. A proper chemical or electrochemical reaction is needed

Example : Salt in water is a mixture. We can add any amount of salt in a glass of water, and call the resultant a mixture. 

The amount of either of the things doesn't matter.

The property of the mixture is the same as that of the constituents salt and water.

Example : CO 2 is a compound . It is only formed when 1 atom of carbon combines with 2 Atoms of Oxygen. 

Carbon and Oxygen should always combine in a ratio of 1:2 to form CO 2 .

The property of CO 2 is different from that of Carbon and Oxygen

 

 

Difference between Distillation and Fractional Distillation

 

 

Distillation

Fractional Distillation

It is used to separate liquids with higher difference in boiling points (>25 O C)

It is used to separate liquids with less difference in boiling points (<25 O C)

It uses a simple apparatus; 2 flasks and a condenser. No fractionating column is used

It uses a fractionating column additionally



We need to repeat the process multiple times to obtain pure liquids




We do not require to be repeated many times (as distillation / heating and cooling, takes places multiple times in one round of fractional distillation) 

Solvent can be separated from solute using distillation. 

Solvent cannot be separated from solute using fractional distillation. 

Uses

  • It is used to separate acetone from water
  • It is also used to purify sea water



Uses

  • It is used to refine crude oil (convert crude oil into different components like petrol,diesel,kerosene)
  • It is also used to obtain different gases from air

 

 

  1. Class 9
  2. Chapter 2 Class 9 - Is Matter Around Us Pure

About the Author

CA Maninder Singh's photo - Founder at Teachoo
CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 11 years and a teacher from the past 11 years. He teaches Science, Accounts and English at Teachoo