SORTING MATERIAL INTO GROUPS (post -2 )

Good morning boys !
 In the last class you learnt that
-things are made up of different materials.
- different things can be made from the same material 
 -an object can be made from different materials.

LEARNING OUT COMES OF THIS CLASS- 
BY THE END OF THE CLASS YOU WILL BE ABLE TO-
- classify materials on the basis of their physical state.
- classify materials on the basis of their appearance.
- classify materials on the basis of their solubility in water.

PHYSICAL STATE-
Materials can be classified as solids , liquids or gases easily by seeing or touching them. Colourless gases like air cannot be seen but can be felt on our skin.




TRY THIS !
1. Do solids have a definite shape and volume ?
2. Do liquids have a definite shape and volume ?
3. Do gases have a definite shape and volume?

APPEARANCE-
Appearance of any material can be described in terms of any one or more of the following-
COLOUR-
Natural materials have have their characteristic colour.
For example -Gold is golden yellow in colour.


Copper is reddish-brown in colour.


Silver is white in colour.



LUSTRE- 
 The shine an object possesses is called lustre. All metals have lustre . Some metals like copper , aluminium ,silver lose their shine/lustre  when exposed to humid air. Once they are cleaned ,they start shining once again.
 Materials like wood ,do not possess lustre.

TEXTURE-
Certain materials like silk  are smooth to touch.


 Certain materials like wool  ,jute ,are rough to touch.


HARDNESS-

-Some materials like stone , metal are hard . Diamond is the hardest known material. It can even cut glass.


Some materials like cotton are soft. Cotton is also  light because it traps a lot of air.




SOLUBILITY IN WATER-


-Salt,sugar ,ink, lemon juice, oxygen (gas), carbon di oxide( gas) are soluble in water. Aerated drinks contain dissolved carbondioxide.
The  mixture containing the soluble substance and water is called solution.
https://www.bing.com/videos/search?

You have see in the above video , that in a sugar solution ( sugar + water) , sugar is the solute and water is the solvent. When a solute completely dissloves in a solvent , a solution is formed.

HOTS!
Which gas do aquatic plants use for the process of photosynthesis ?
Which gas do aquatic animals use for respiration ?

-Gases like nitrogen , methane and helium are insoluble  in water.
-Chalk powder , sand , oils ( kerosee, petrol ) are insoluble  in water.

MISCIBLE AND IMMISCIBLE LIQUIDS- 
Depending if a liquid totally mixes with water( or another liquid ) or not, they can be classified as follows-




DO THE FOLLOWING QUESTIONS IN YOUR NOTEBOOK-

3. Define the terms-
a) Lustre - It is the shine an object possesses.
b)Solution- The  mixture containing the soluble substance and water is called solution.

4. Give examples of the following-
a) Two  gases that are soluble in water.        ....oxygen....  
.carbon dioxide...........
b) Two gases  that are insoluble in water.       ..nitrogen....   ..helium....................
c) The hardest material that can even cut glass.  .diamond........
d) Miscible liquids.        ....water and alcohol......
e) Immiscible liquids .     ...water and oil...........

5. DISTINGUISH BETWEEN THE FOLLOWING-
a) Soluble and insoluble substances

ans:    Soluble substances                     Insoluble substances
           Substances that mix                   Substances that do not mix 
               totally in water.                       in water.            
           eg. salt in water                         eg. chalk in water

b)  Miscible liquids                         Immiscible liquids
    Two  liquids that mix                  Two liquids that do not mix
    totally mix.                                   in each other.                               
     eg. lemon juice and                  eg. oil and water
      water.

THIS IS ALL FOR TODAY BOYS ! HAVE A GOOD DAY!