Video Transcript
When designing an electrolytic
cell, what is a major disadvantage of using platinum electrodes? (A) They have a lower melting point
than most molten salts. (B) They are very expensive. (C) They are very reactive. (D) They are nonconductive. (E) They easily degrade.
Electrolysis is a chemical process
where an electric current is passed through a liquid or a solution containing
ions. This liquid is called an
electrolyte. The flow of electric charge causes
the substances inside to decompose. This process is performed using an
electrolytic cell. The electrolytic cell typically
contains a molten liquid electrolyte, electrodes, and is powered by a DC power
supply.
There are a lot of factors to
consider when designing an electrolytic cell. We need to choose the best
conditions for the operation of the cell, such as the speed at which the products
will be produced, the temperature that is required to keep the electrolyte molten,
and any potential side reactions that might occur. The material that the electrodes
are made from will also influence these factors.
It would be ideal if electrodes
would not degrade. However, almost all electrodes will
begin to break down and lose their efficacy over time. This is due in part to the chemical
reactions taking place and also the high temperatures that are required to keep the
electrolyte solution molten. For these reasons, materials like
platinum are perfect for electrodes.
Platinum is nonreactive, or inert,
and so is less likely to take part in a secondary reaction. Platinum also possesses a very high
melting point, so it will not easily degrade. Unfortunately, platinum is one of
the most expensive materials on Earth and is therefore cost prohibitive. Material like carbon is much more
reactive but very cheap and is therefore used frequently regardless of secondary
products or degradation. Because carbon is so cheap when
compared with platinum, secondary products may be acceptable, and they can be
removed later.
To summarize, what is a major
disadvantage of using platinum electrodes? A major disadvantage would make
platinum not a good choice for an electrode, even though many of its properties are
desirable. In conclusion, answer choice (B) is
the correct answer because when designing an electrolytic cell, the major
disadvantage of using platinum electrodes is that they are very expensive. We could say that platinum is cost
prohibitive. “They are very expensive” is the
correct answer.
