Video Transcript
A student would like to
electroplate a steel spoon with copper. What description of the apparatus
would result in a successful experiment? (A) Use iron(II) sulfate as the
electrolyte, make the spoon the anode, and use a copper rod for the cathode. (B) Use copper(II) sulfate as the
electrolyte, make the spoon the cathode, and use a copper rod for the anode. (C) Use iron(II) sulfate as the
electrolyte, make the spoon the cathode, and use an iron rod for the anode. (D) Use copper(II) sulfate as the
electrolyte, make the spoon the anode, and use a copper rod for the cathode. Or (E) use copper(II) sulfate as
the electrolyte, make the spoon the cathode, and use an iron rod for the anode.
First of all, let’s rewrite the
answer choices in a tabular form to create more space.
Electroplating involves
electrolysis. The setup for electrolysis involves
a power source hooked up to two electrodes, a negative cathode and a positive
anode. A liquid electrolyte that contains
ions allows for a continuous circuit to be maintained. This allows positive ions to flow
towards the cathode and the negative ions to flow towards the anode.
So, we are asked to determine how
to electroplate a steel spoon with elemental copper. To do this, we need to get the
copper ions from the electrolyte solution. Therefore, we need to use
copper(II) sulfate as an electrolyte solution. We can thus eliminate answer
choices (A) and (C) as they state that the electrolyte is iron(II) sulfate.
Since we know that the positive
copper ions will flow to the negative cathode, and we want the copper ions to flow
to the steel spoon and coat it, we need to make our spoon the cathode. We can then eliminate answer choice
(D) as it states that the spoon is used as the anode.
So what will the anode be made out
of? The anode should be made from a
copper rod because it will be oxidized to form Cu2+ and migrate towards the spoon,
causing the spoon to be plated with copper. So, for our apparatus to result in
a successful experiment, we will need to use copper(II) sulfate as the electrolyte,
use a copper rod for the anode, and make the spoon the cathode.
Let’s now bring back the original
answer choices. We now know that the correct answer
is answer choice (B): use copper(II) sulfate as the electrolyte, make the spoon the
cathode, and use a copper rod for the anode.
