does UV radiation have the ability to break up water molecules? if so please specify the wavelength

Electrolysis takes about 1.25 eV

 

wavelength = hc/E

ok, what is hc and what is E?

h is Planck's constant, c is the speed of light and E is energy

 

hc=1240 eV nm

 

So that means the wavelength needs to be 1000 nm or shorter, which covers all the visible spectrum and gets you into the near-IR. This doesn't seem right — the electrolysis energy includes breaking off the Oxygen but also forming an O2 molecule, and happens in the presence of other molecules.

 

This calculation

http://answers.yahoo.com/question/index?qid=20081107045616AAfd4jT

 

says that you need about 5.25 eV to split off a hydrogen, which happens at 237 nm or shorter

Water is transparent to UV light sown to at least 190nM so that calculation is wrong.

Water is transparent to UV light sown to at least 190nM so that calculation is wrong.

 

Vapor or liquid? AFAIK the liquid spectrum shifts the resonances to longer wavelengths

I found some data. In the gas phase the absorbtion maximum is at about 167nM

I can't find any data for the liquid but it's certainly below the UV cutoff of most instruments because air absorbs from about 190 nM.

so anything under 190nm will do?

In principle yes. the yeild will get better as you go towards 167nm.

Have fun trying to set this up; air is opaque to those wavelengths.

why is air opaque to those wavelengths?