The chemical changes are changes in substance that produces a new substance with new properties, which is referred to as a chemical reaction. Change agents can not return to its original shape.
The hallmark of the chemical changes of a substance, namely: the formation of new types of substances, followed by changes in the chemical properties through chemical reactions, and substances that can not be changed back to its original shape.
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During the occurrence of chemical change, then the mass of matter before the reaction as well as the mass of matter after the chemical reaction.
The occurrence of chemical changes caused by:
1. Occurs as a result of combustion
2. Occurs as a result of mixing substances
3. Occurs as a result of electricity
4. occurred as a result of mixing two or more substances that produce new types of substances:
1). When refilling the battery
2) .Asam chloride + Sodium hydroxide
Some examples of chemical changes :
1. apples rotting
2. Paper were burned to ashes
3. The compost is in the process of dry leaves
4. Burning gasoline in motor vehicles
5 . the rice is stale
7. soybeans are made in the manufacture of materials and tofu
8. the meat is baked into the sate
9. Burning logs into charcoal
10. eat in the dining and processes in the living body becomes stool / faeces)
11. white skin turned black because most bask under the hot sun
12. Milk becomes sour due to the formation of new substances, namely lactic acid
13. Firecrackers exploded produce different forms in their original form
14. Potatoes and apples that have been in peeled let a few seconds, will produce color brown spots.
15. Iron to rust, iron Fe into different Fe2O3 with iron.
16. Cassava made into fermented to produce different shapes and flavors 17. Sugar is heated to a liquid 18. The process of refining gold using mercury 19. The mixing acids and bases to be salt and solvent 20. The formation of red blood cells in bone marrow
In addition to the chemical changes, some are referred to as physical changes. Physical change is a change of substances that do not produce new substances, because of the absence causes chemical changes in the composition of the substance. The composition of the compound changes in physics have remained atoms, for example, changes in the form of substances, changes in volume, and the change in length.
The composition of the molecule is always fixed, although the form of substance changes.
Examples of physical changes:
a. Frozen ice becoming liquid.
b. The water that evaporates into water vapor.
c. The air we breathe
d. Mencampu tea with sugar
e. Boil water
f. Fry with butter.
The hallmark of the physical change is not the formation of a new type of substance, and the substance can be changed in shape.