00:02
So in this question, we are asked for the wavelength.
00:06
And what we're given is the energy.
00:09
And specifically, we're given the energy in kilojoules per mole.
00:19
So if we think about how we're going to get the wavelength, the only equation that relates energy to wavelength is the equation e photon.
00:28
So the energy of a single photon is equal to hc over lambda, where h is planck's constant and c is the speed of light.
00:42
Now this energy is in joules and it's just for a single photon.
00:52
So the first thing that we have to do before you can use this equation and find the wavelength is we have to convert this energy into the energy in joules of just a single photon.
01:04
So if we start first with converting the kilojoules to joules, so one kilojoule, 1 ,000 joules, right? so now the kilojoules cancels.
01:23
And then we have the mole at the bottom.
01:25
Right, just re -write it to get clear.
01:29
And that's a mole of photons.
01:32
So if you want to get rid of that, we need to put a mole on top here.
01:37
So mole, and in one mole of photons, just like anything, we have 6 .022 times 10 to the 23rd of that thing, right? and this case photons.
01:58
Okay, so if we look at our units, the moles will cancel, right, and we'll be left with jewels for photon.
02:08
And so when we enter that in the calculator, what we get is 3 .54 times 10 to the negative 18 joules per photon.
02:26
Right, so now we can use this equation to get from the energy of 1 .4 times 10 to the negative 18 joules per photon...
