Video Transcript
Which of the following images best
represents a thermal decomposition reaction?
In this question, we are being
asked to determine which of the images below shows a thermal decomposition
reaction.
A decomposition reaction is a type
of chemical reaction in which a compound is broken down into simpler substances. The simpler substances that are
produced in the reaction may be compounds or elements. Sometimes, it’s necessary to heat a
substance to cause a decomposition reaction to occur. We refer to this type of reaction
as a thermal decomposition reaction. Therefore, we can define a thermal
decomposition reaction as the breaking down of a substance when heated to form two
or more other substances.
If we look at the images we can see
that circles of different colors have been used to represent different atoms or ions
in various compounds. Each image also contains an arrow
with a triangle symbol above it. This symbol, known as Δ, indicates
that the reactants are being heated.
We know that when a thermal
decomposition reaction occurs, two or more different products will be formed. We can see that reactions (A) and
(B) only produce a single compound. Because these reactions only form
one product, they are not thermal decomposition reactions.
Our definition of a thermal
decomposition reaction also tells us that the reaction must have only one
reactant. In other words, the image must have
a single chemical compound as a reactant. In reactions (C) and (D), a plus
sign is used to indicate that there are two different reactants. Therefore, these two reactions are
not thermal decomposition reactions.
You might also have noticed that in
these two reactions, some of the colored circles have changed positions. So, these reactions are likely to
be substitution reactions.
As for reaction (E), we see that
one chemical compound reacts to form two different products. This fits well with our definition
of a thermal decomposition reaction. Therefore, the image that best
represents a thermal decomposition reaction is image (E).
