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

Jun 10, 2016

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:

$\text{NH"_4"NO"_3 stackrel(Delta" ")(->) 2"H"_2"O" + "N"_2"O}$

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:

$\text{CH"_4 + "Cl"_2 stackrel(Delta" ""or " hnu" ")(->) "CH"_3"Cl" + "HCl}$

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