Actually, cast-iron pots will heat less evenly
than aluminum pots, for instance, since iron is a
poorer conductor of heat. Furthermore, compared to
iron, aluminum also has a higher specific heat
capacity -- it takes more energy to raise a unit
mass of aluminum by one degree Celsius than iron.
However, iron is more dense than many of its
competitors. What does this mean? Well density =
mass/volume. So if we compared, for example,
aluminum and iron pans of the same volume, the
iron pan would have more mass (is heavier). So far
so good, right? "OK, great, why do we care about
This means that even though iron has a lower
specific heat capacity than aluminum, it can still
store more thermal energy in a pan of the same
volume at the same temperature. How? Q = m c ∆T,
where Q is the heat energy, m is the mass, c is
the specific heat capacity, and ∆T is the change
in temperature. If m is a lot higher for iron,
then Q will also be a lot higher for the same ∆T
as compared with aluminum.
Let's think about what this means. An iron pot
will take longer to heat up to a certain
temperature than an aluminum pot, but will store
more thermal energy than the aluminum pot at the
same temperature. So once it gets to that
temperature, it has more thermal energy to
transfer to the food we are trying to cook!
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