1. The problem statement, all variables and given/known data Calculate the size of the quantum involved in the excitation of a molecular vibration of period 20 fs. Express the results in joules and kilojoules per mole. 2. Relevant equations ΔE = h/t 3. The attempt at a solution I converted fs to seconds and used the above equation to figure out the answer in terms of joules, no problem. I have checked my answer for this, so I know it is correct. I also know what the answer is in terms of kilojoules per mole, but I can't for the life of me figure out exactly how to convert between the two. It doesn't seem as though I'm given enough information in the problem to do this conversion. I assumed that I would need to use the fact that 1000J=1kJ, but that doesn't seem to match up with the answer sheet that I was given.