Physical and chemical changes (Physical changes ( (Examples of physical…
Physical and chemical changes
Affects only the properties of the objects
They don't change the nature of the substances that make up the objects.
After a physical change, a substance will still be the same substance.
Expnsion, contraction and changes of state are physical changes caused by the changes of temperature.
Depending on the temperature substances will have different properties
Examples of physical changes:
Deform an object
Break an object
Disolve two substances into a homogeneous mix
Change of state
A chemical change occurs when one or several pure subtances turn into different pure substances.
The original substance that undergoes a change is called a reactant, the substance that results the change is called the product.
There are different ways to detect a chemical change:
The original substance and the new one have different colors
The original substance and the new one give off different smells
The newly formed substances have, at the same temperature, a state of aggregation different than the state of aggregation of the original ones.
There are three types of reactions:
: Two or more reactants turn into two or more prroducts.
: In a synthesis reaction, two or more reactants combine togenerate one products.
: A reactant generates or decomposes into two or more products.
Sometimes the chemical changes are related to changes in temperature
Chemical changes are difficult to reverse