Video Transcript
Which of the following statements
about the following ionic equation is incorrect? Zn solid plus 2Ag+ aqueous react to
form Zn2+ aqueous plus 2Ag solid. (A) Zinc atoms becoming zinc ions
is oxidation. (B) Silver ions becoming silver
atoms is reduction. (C) Zinc acts as a reducing
agent. (D) Silver ions gain electrons. Or (E) zinc atoms becoming zinc
ions is reduction.
In this reaction, we have zinc in
its elemental solid form reacting with silver ions in solution. And our products are zinc ions in
solution and solid silver. Our job is to examine the
statements and find the incorrect statement. The first statement is that zinc
atoms becoming zinc ions is oxidation. We can use our mnemonic LEO the
lion says GER to tell us what oxidation and reduction are. LEO expands to the loss of
electrons is oxidation and GER expands to the gain of electrons is reduction. From the equation, we can see zinc
is being transformed into zinc two plus. This corresponds to the removal of
two electrons.
We can also see silver plus ions
transforming into silver atoms. This particular process involves
two electrons being added. We can see that zinc atoms in this
case are becoming zinc ions and losing electrons. This statement is true. Therefore, it can’t be our correct
answer. Next, we have silver ions becoming
silver atoms is reduction. We can see from our equation that
the silver ions are gaining electrons forming silver atoms. Therefore, this is reduction and
this statement is true and therefore not our correct answer.
The third statement requires a
little bit more insight than we’ve got thus far. Zinc acts as a reducing agent. What’s a reducing agent? A reducing agent reduces something
else by giving it electrons. We can see from the equation that
each zinc atom is giving up two electrons, one each to two silver plus ions. Since it’s giving up electrons,
it’s acting as a reducing agent. So this statement is also true. And since we’ve already discussed
that it’s the silver ions that receive the electrons, we know that silver ions gain
electrons is a true statement and therefore not our correct answer.
The last statement suggests that
zinc atoms becoming zinc ions is reduction. But we know that in this process,
the zinc atoms are losing rather than gaining electrons. So this is not reduction. This is oxidation. So the five statements given about
the ionic equation, the only one that’s incorrect is that zinc atoms becoming zinc
ions is reduction.
