Video Transcript
Which of the following cannot be
used as a sacrificial metal to prevent the corrosion of tin? (A) Magnesium, (B) aluminum, (C)
zinc, (D) lead, or (E) iron.
Corrosion is a damaging,
irreversible process in which a metal combines with other substances to produce more
stable compounds. The use of a sacrificial metal
through the process of sacrificial protection can help to mitigate the effects of
corrosion. Sacrificial protection can be
defined as the use of a more reactive metal to protect a less reactive metal against
corrosion. During this process, the
sacrificial metal will oxidize in place of the metal we are trying to protect. So the sacrificial metal is the
metal that is more reactive and is used to protect the less reactive metal against
corrosion, as it is oxidized in its place.
Tin corrodes when it reacts with
oxygen in the air. To prevent the corrosion of tin, a
metal more reactive than tin must be used as the sacrificial metal. Let’s look at the list of metals
from least reactive at the bottom to most reactive at the top.
As you can see, magnesium,
aluminum, zinc, and iron are all more reactive than tin. So they could theoretically be used
as sacrificial metals for tin. Lead is the only one that is less
reactive than tin. Lead would not work as a
sacrificial metal for tin because it is less reactive and has a lower tendency to
oxidize than tin does. Therefore, the correct answer is
(D), lead.
