This shows solid water (ice) added to liquid water. This is an example of the solid and liquid water and the physical change of solid water forming liquid water.
This shows NaCl solid added to water. This is an example of the dissolution of NaCl in water. An example of an ambiguous change. Here is a video depicting the dissolution of NaCl at the particulate level.
Examples of Chemical Changes
As an example of a chemical reaction we watched the reaction
between iron, Fe(s), and sulfur, S8(s), on video.
There are some additional
reactions on our Web site that you can review. We noted the
physical properties of both iron and sulfur before the reaction
and the physical property of the product of the reaction. The
magnetic property of iron, present when iron was in its elemental
form, was absent in the product. The yellow color of the sulfur,
present in the elemental form as a reactant was absent in the
product. Yet both iron and sulfur are in the product. Since the
properties changed the product is a new substance.
This is the reaction betweeen Mg and Br2.
Here is an example of two precipitation reactions.
In the first example a solution labeled NaCl(aq) and a solution
labeled AgNO3(aq) are mixed.
In the second example a solution labeled NaI(aq) and a solution
labeled AgNO3(aq) are mixed.
This is an introduction to oxidation-reduction processes and what
it means for a substance to lose or gain electrons.
Another example of oxidation-reduction reaction viewed at the
particulate level.
Here is an oxidation-reduction reaction at the macroscopic level.
Can you write the reaction that occurs?
This is an example of a single replacement reaction between Cu
metal and silver nitrate.