Video Transcript
Which of the following statements
about oxidization and reduction is correct? (A) Oxidization can happen
independently of reduction. (B) Reduction happens before
oxidization. (C) Oxidization happens before
reduction. Or (D) oxidization and reduction
happen concurrently.
We can define oxidization and
reduction in terms of oxygen atoms, hydrogen atoms, or electrons. Oxidization can be defined as a
chemical process that increases the oxygen percentage or decreases the hydrogen
percentage in a substance, whereas reduction is the opposite. It is a chemical process that
decreases the oxygen percentage or increases the hydrogen percentage in a
substance. In this example, hydrogen forms
water when it reacts with copper oxide. When hydrogen forms water, there is
an increase in the oxygen percentage. Thus, hydrogen has undergone
oxidization.
For the hydrogen to receive this
oxygen, the oxygen must have come from somewhere else. It has come from the copper
oxide. As the copper oxide forms copper,
there is a decrease in the oxygen percentage for the substance, so the copper oxide
has undergone reduction. So we can see here that oxidization
and reduction are happening in the same reaction.
If we look at another example, we
can see that when bromine reacts with ammonia, hydrogen bromide is formed. When bromine forms hydrogen
bromide, there is an increase in the hydrogen percentage. Thus, bromine has undergone
reduction. For bromine to have gained this
hydrogen, another chemical must have lost it. This chemical is ammonia. Ammonia loses hydrogen, forming
nitrogen. So as the hydrogen percentage in
the substance has decreased, we say that ammonia has undergone oxidization. So again, oxidization and reduction
are happening in the same reaction.
We have now looked at the
definition of oxidization and reduction in terms of oxygen and hydrogen and have
seen an example in each case, where oxidization and reduction are happening at the
same time. Let’s now look at the definition of
oxidization and reduction in terms of electrons. Oxidization can be defined as a
reaction that involves the loss of electrons from a substance, whereas reduction is
the opposite. It is a reaction that involves the
gain of electrons in a substance. In this example, chlorine gas
reacts with sodium. When sodium reacts as a metal, it
tends to form positive ions. Sodium chloride is an ionic
compound. It is formed from sodium ions and
chloride ions.
For neutral sodium to form positive
ions, it must lose electrons from its valence shell, so sodium has undergone
oxidization. When sodium loses these electrons,
they are gained by chlorine, which is why chlorine goes from a neutral species to a
negatively charged species. As chlorine has gained electrons,
it has undergone reduction. So again, we have seen that
oxidization and reduction are happening in the same reaction. We have now seen this happen for
reactions where there is an increase or decrease in oxygen percentage, hydrogen
percentage, or the number of electrons. We have seen that oxidization and
reduction depend on each other.
For one of them to occur, the other
must also occur. For oxidization to occur, reduction
must occur in the same reaction, so oxidization and reduction are happening at the
same time. Another word for saying at the same
time is concurrently. So the statement “oxidization and
reduction happen concurrently” is correct. Therefore, the answer to the
question “Which of the following statements about oxidization and reduction is
correct?” is (D). Oxidization and reduction happen
concurrently.