Video Transcript
Ancient civilizations used
different types of chemical reactions to produce many valuable and useful materials
that helped ancient societies to function normally. Which of the following is an
example of a product that was not formed through ancient chemical reactions? (A) Glass, (B) stone sculptures,
(C) medication, (D) colored dye, or (E) bronze metal.
A chemical reaction causes chemical
change. A chemical change is often
irreversible or can only be reversed with an additional chemical change. For example, silica, or sand, can
be chemically changed through heating to produce glass. Similarly, copper and tin can
chemically combine to form bronze metal. Neither of these products can be
reversed and therefore are examples of chemical changes.
The ancient Egyptians created a
colored pigment, Egyptian blue, by mixing limestone with sand and azurite. The chemical properties of the
reactants and products are different, and the change is irreversible. Therefore, it is a chemical
change. Tinctures and teas were often used
in ancient medicine. This involved heating herbs like
𝐸𝑐ℎ𝑖𝑛𝑎𝑐𝑒𝑎 or elderberry in water. This extracts beneficial compounds,
which cannot be returned. Thus, the process is
irreversible. From what we have seen so far, we
can eliminate answer choices (A), (C), (D), and (E).
We are left with answer choice (B),
stone sculptures. No ingredients are mixed to form
the sculpture. Stone sculptures are formed by the
stone being hammered, chiseled, and ground down. A stone sculpture is formed through
physical change. Common examples of a physical
change are heating, cooling, cutting, tearing, shattering, or grinding. But it’s important to note that
processes such as heating can also facilitate chemical change.
Additionally, a physical change is
often reversible, meaning it is not a permanent change and can be brought back to
the original state. Most importantly, physical changes
do not affect the chemical composition of a substance. We can now be sure that of the
given options, the one that is an example of a product that was not formed through
ancient chemical reactions is (B), stone sculptures.
