The change in the color of tree leaves in autum

Green plants makes its own food by a process called photosynthesis.Photosynthesis takes place in the presence of chlorophyl and sunlight according to the equation below:
6CO2  +   6H2O                                    C6H12O6
                      chlorophyl and sunlight

In autumn, however, changes in temperature and rainfall amounts cause trees to stop producing
chlorophyll. The chlorophyll already in the leaves undergoes a
chemical change into colorless chemicals.Where do the bright fall
colors come from? The pigments that produce fall colors have
been present in the leaves all along. However, in the summer,
chlorophyll is present in large enough amounts to mask these pigments.
In the fall, when chlorophyll production stops, the bright
pigments become visible.

 

chemical changes around us



rusting is a chemical change



fireworks are due to chemical changes



rusting of roof is a chemical  change

changes in the leaves are due to chemical change

burning wood is a chemical change

cooking meat is a chemical change

Diferentiate between physical and chemical change

Prepare the recipe of cake :  6 eggs -3cups of wheat  -1cup of milk-2small spoons of baking powder -half a small spoon of vinella -1.5 cup of sugar .
Mix these ingredients with a mixer .
Can you still smell the egg  ?Leave it for a time ,is there change in color?Is there formation of gas ?Touch the jar does it turn hot or cold with time  ?
Mixing the ingredients of the cake is not giving a new substance .Is it a physical change  or chemical change ?.

Bake the cake .What kind of change is taking place ?Explain by giving evidence ....

Differentiate between chemical and physical changes

Grind chalk-Cut paper into pieces -dissolve sodium chloride salt in water -pulverize sugar crystals ......
Do you observe change in color ?
Do you smell anything ?
Do yo see effervesence of gas?
Is the container turning hot ?
Can you see light  formed ?
Al these changes are physical changes as no new substances are formed .
  
Add lemon to chalk-burn sugar on fire -burn a piece of paper -put baking powder and vinegar......