UV/IR Photons

PsychoDragon · Probably a bot. Joined: 27 Mar 2008 Posts: 1

I just really need help on what formula and the steps I need to get the answer. If you give the answer then I could use it to check my answer. I would appreciate the help alot.

'UV photons are capable of breaking chemicals bonds, while IR photons can cause only vibration in a bond. SHOW YOUR WORK.

-Calculate the energy associated with an UV photon at 320nm.

-Calculate the energy associated with an IR photon at 5000nm.

-Calculate the ratio of the energy that breaks bonds to the energy that causes vibration.'

Hix3r · Regular Joined: 24 Apr 2007 Posts: 43 Location: Hungary

The formula required here is this:

E = h*f

where h is the Planck constant and f is the frequency. You can get the frequency from this:

f = v/λ

Where v is the speed of light, λ is the wavelength. Everything must be in SI units. So from here it is simple:

f1 = 3.2*10^-7*3*10^8 = 937500000000000 Hz

f2 = 5*10^-6*3*10^8 = 200000000000000 Hz

E1 = 6.626*10^-34*937500000000000 = 6.211875*10^-19 J

E2 = 6.626*10^-34*200000000000000 = 1.3252*10^-19 J

E1/E2 = 4.6875

so basically you need 4.6875 times more energy to break a bond than to just vibrate one.