00:03
We're told to consider one type of sunburn that occurs with exposure to uv light with a wavelength approximately equal to 305 nanometers.
00:21
Find the energy of a photon for this wavelength.
00:39
You know energy equals planck's constant times c divided by lambda.
00:49
I've got room for my lambda.
00:51
So lambda.
00:52
Oh no, that's right.
00:53
So this will be my energy will equal to planck's constant 6 .636.
01:03
Why am i? sometimes i draw blanks on the dumbest things.
01:23
And that is 6 .626.
01:26
I knew i was doing that wrong.
01:28
Times the speed of light divided by my wavelength and i'm just going to go ahead and convert that right here.
02:00
So let me do this math.
02:02
6 .626 times 10 to the minus 34 times 3 times 10 to the 8th divided by 305 times 10 to the minus 9th.
02:18
And this will equal 6 .52 times 10 to the minus 19th joules per photon.
02:32
That's a or 1.
02:36
Let me go see what this is.
02:38
That is a.
02:43
B.
02:44
What is the energy of a mole? that'll be 6 .52 times 10 to the minus 19th joules per photon times avogadro's number of photons per mole.
03:19
I'm just going to take the number of my calculator times 6 .022 times 10 to the 23rd...