Physical change - is the change of substance that is temporary while the structure doesn’t change, but the shape changes.
- a physical change is reversible process and doesn’t create a new matter
Chemical change - is the change of structure that is permanent and also the structure and the shape changes.
- a chemical change is irreversible process and create a new matter
Some example about the matter change !
Water heats, paper burns, ice melting, melting, cooling, freezing, boiling, vaporizing, sublimating, condensing, burning, corroding, iron covered with paint , rusty iron, vaporized gasoline , frozen water, rotten garbage, exploded firecrackers, burned kerosene.
- Can be identified based on the change happening in the reaction
- Some changes can be in the form:
v Color changes
v Gas production
v Temperature changes
Chemical reaction that produces precipitation
n Examples: when limewater is blown, it will cause a reaction between the water with carbondioxide, the result white calcium carbonate
Chemical reaction that produces change of color
n Reaction between cassava flour and tincture iodium, it will produce blue color
n The color change when the cut apple exposed to the air for a while, its color into brown
Chemical reaction that produces gas
n Example : when mix carbide with water, it will form acetylene that commonly used to join metals in a welding process and to ripen some fruits.
Chemical reaction that produces a change of temperature
n When you mix carbid with water, you can feel the rising temperature on the wall of the glass where the reaction takes place.
n All reaction always involve energy.
n One chemical eaction that produce energy is called exothermic.
n One chemical eaction that needs energy is called endothermic,
Example : photosynthesis process.