Video Transcript
Electroplating steel with tin is
one way to prevent the steel from rusting. Which setup of equipment would
ensure the correct results? (A) The anode is the piece of steel
we want plated, the cathode is made from tin, and the electrolyte is an aqueous tin
salt. (B) The anode is made from tin, the
cathode is the piece of steel we want plated, and the electrolyte is an aqueous tin
salt. (C) The anode is made from
graphite, the cathode is the piece of steel we want plated, and the electrolyte is
an aqueous tin salt. (D) The anode is made from tin, the
cathode is the piece of steel we want plated, and the electrolyte is an aqueous iron
salt. Or (E) the anode is the piece of
steel we want plated, the cathode is made from graphite, and the electrolyte is an
aqueous iron salt.
Let’s rewrite the answer choices in
a tabular form to give us more space. Electroplating involves
electrolysis. An electrolysis reaction is a
reaction that uses an electrical current that is passed through a solution or liquid
and causes substances to decompose or break apart. The apparatus necessary for these
reactions involves a power source, an anode, a cathode, and an electrolyte
solution.
To ensure a continuous circuit
between the two electrodes, a liquid electrolyte containing the compound to be
broken apart is added to the cell. The ions from the compound within
the electrolyte will then flow towards their respective electrode. Positive ions will flow towards the
negatively charged cathode. And the negatively charged ions
will flow to the positively charged anode.
So, we’re asked to determine how to
electroplate steel with elemental tin. If we want to electroplate steel
with tin, we need to get the tin ions from the electrolyte solution. Therefore, we will need to use an
aqueous tin salt as an electrolyte solution. Therefore, we can eliminate answer
choices (D) and (E).
An aqueous tin salt solution forms
a positively charged tin cation, Sn2+, meaning that tin is a metal that will migrate
to the negatively charged cathode in its pure elemental form. We want the tin ions to coat the
steel, so we need to make steel act as the cathode. Now, we can eliminate answer choice
(A), as it tells us that the cathode should be made from tin and not steel. So, what will the anode be made out
of?
The anode should be made from tin
because the electroplating reaction will cause tin ions to move from the tin
electrode towards the cathode. The proper setup of our equipment
for our electroplating reaction to occur is a tin rod for our anode, the steel piece
as our cathode, and an aqueous tin salt solution for the electrolyte.
Let’s bring back the original
answer choices. The correct answer is (B). The anode is made from tin, the
cathode is the piece of steel we want plated, and the electrolyte is an aqueous tin
salt.
