Question

What does the symbol `Delta` in a chemical equation mean?

Answer 1

It means heat. So you could put something on a hot plate, crank up the temperature... then you'd be carrying out the action indicated by `Delta`.

So you might see something like:

`"NH"_4"NO"_3 stackrel(Delta" ")(->) 2"H"_2"O" + "N"_2"O"`

That would be the decomposition of ammonium nitrate into water and nitrous oxide. The `Delta` then tells you to heat the compound to promote this decomposition.

Another example is the radical halogenation of alkanes:

`"CH"_4 + "Cl"_2 stackrel(Delta" ""or " hnu" ")(->) "CH"_3"Cl" + "HCl"`

In this case, `Delta` still means heat, but for this photochemically-catalyzed reaction, you could have also used UV light, which was indicated by `hnu` since `E = hnu` tends to be used to evaluate the energy of a photon (or a `"mol"` of photons).