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Conclusion
Chemical Reaction,
process by which atoms or groups of atoms are redistributed, resulting in a
change in the molecular composition of substances. An example of a chemical
reaction is formation of rust (iron oxide), which is produced when oxygen in
the air reacts with iron.
Oxidation: A chemical Reaction
In Really Life
Oxidation, in its original
sense, refers to the combination of oxygen with another substance to produce
a compound called an oxide. Iron, in the presence of water, combines with
atmospheric oxygen to form a hydrated iron oxide, commonly called rust.
Question
What is the
difference between a physical change and a chemical change?
Asked by: Tim Meyer
Answer
There are
two possible definitions for Physical and Chemical changes which I use in
school:
1. A physical change is reversible, a chemical change is not. For example,
the freezing of water would be a physical change because it can be reversed,
whereas the burning of wood is a chemical change - you can't 'unburn' it
2. A physical change is a change in which no new substance is formed; a
chemical change results in the formation of one or more new substances.
Again, consider the previous examples: Freezing water into ice just results
in water molecules which are 'stuck' together - it's still H2O.
Whereas burning wood results in ash, carbon dioxide, etc, all new substances
which weren't there when you started.
- Chemical vs.
Physical Changes.
- In a physical
change, the substances are not altered chemically, but merely
changed to another phase (i.e. gas, liquid, solid) or separated or
combined.
- In a chemical
change, the substances are altered chemically and display different
physical and chemical properties after the change.
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