Question

The energy required to split apart hydrogen bromide according to the equation is 6.01 × 10-19 J/molecule.

HBr(g) → H(g) + Br(g)
Calculate the wavelength (m) of the photon that can dissociate hydrogen bromide. Express answer in scientific notation.

Answer 1

This is sort of a blur to me since it's been quite some time, but I think you use:
\[E = hf = \frac{ hc }{ \lambda }\]
where the greek symbol, lambda, represents wavelength.

Answer 2

I think Abb0t is right on the money again. I believe h is Planck's constant in this equation:

http://en.wikipedia.org/wiki/Planck%27s_constant