[greenglaze]

Hi,

I am having touble figuring out the following questions. I tried a lot of different methods, but they don't seem to work.

1. A photon with a wavelength λ = 209 nm has just enough energy to dissociate one X2 molecule. Determine the energy of the X-X bond (in kJ/mol) .

2. A beam of microwaves corresponds to a flux of ( 9.6x10^0 x 10^20) photons per second with a wavelength of 2.0 cm. Calculate the power carried by the beam (in milliwatts, 1 watt = 1 J/s).

3. The wavelength of a beam of radio waves is 4.608x10^0 km. What is the energy (in J) of 5.13x10^-1 mole of its photons ?

Thanks for your help.

[Borek]

Do you know any formula linking wavelength and energy?

[greenglaze]

I know that Energy=hc/(lambda), but how does that fit into the problem?

[saden99]

You also know E=hv (v being nu).

Both give relations between energy, wavelength and frequency. You have to use both equations to answer your questions.

As a hint to get you started...#1 seems to be a molecule (and 1 mol) absorbing light to break the bond. This one should be rather easy knowing E=hc/lambda...you know lambda!

[opti384]

Just Energy=hc/(lambda) will be enough.

[Borek]

You also know E=hv (v being nu).

ν=c/λ

so we are talking about the same equation all the time.