Video Transcript
The equation CuO solid plus H2 gas
reacts to form Cu solid plus H2O liquid shows how copper oxide can be reacted with
hydrogen to produce copper and water. Which of the following images
correctly identifies the oxidizing and reducing agents in this chemical
equation?
In this question, we are given a
selection of chemical equations showing the reaction between copper(II) oxide and
hydrogen gas. In each of the different answer
options, we can see that one of the products or reactants is labeled as an oxidizing
agent and a second product or reactant is labeled as a reducing agent. Let’s clear some space to discuss
the processes of oxidization and reduction.
It is possible to explain
oxidization and reduction in chemical reactions in a number of different ways. For example, we could describe
oxidization as the addition of oxygen or the loss of hydrogen by a substance. We could describe reduction as the
loss of oxygen or the gain of hydrogen by a substance. It’s also possible for us to
describe oxidization and reduction in terms of electrons being gained or lost. However, with the reaction equation
provided, it’ll be easier for us to use the gain or loss of oxygen to answer this
question.
When identifying which substance in
a reaction is an oxidizing agent and which is a reducing agent, we are referring to
the reactants. A reactant that oxidizes another
reactant is known as an oxidizing agent. On the other hand, a reactant that
reduces another reactant is a reducing agent. If we look at the reaction between
copper(II) oxide and hydrogen gas, we can see that copper(II) oxide loses oxygen to
form elemental copper and is therefore reduced. This means that hydrogen gas, or
H2, must be the reducing agent.
If we were to look at this from a
different point of view, we might say that hydrogen gains oxygen and is oxidized to
become water. Because hydrogen is oxidized,
copper(II) oxide must be the oxidizing agent. Oxidization and reduction cannot
occur independently. And so it is always the case that
when one happens, the other will happen as well.
Let’s bring the answer choices back
up on the screen to determine the correct answer. Now that we know that oxidizing and
reducing agents are reactants, we can eliminate answer choices (B), (C), and (D),
because these answer choices have one or more products labeled as oxidizing or
reducing agents. We can also eliminate answer choice
(E) because the oxidizing and reducing agent labels of the reactants in this answer
choice are reversed.
We can see in answer choice (A)
that copper(II) oxide is labeled as the oxidizing agent and hydrogen is labeled as
the reducing agent. Therefore, the correct answer is
answer choice (A).
