HW 1.23

[Anika_Desar_3N]

Can some please explain how to do 1.23?

[Gabrielle_Giang_2J]

You start off by converting 140.511 keV to Joules. Using dimensional analysis, you do 140.511 keV (1000 eV/1keV) (1.602x10^-19 J/1eV), in which you get 2.23x10^-14 J. Now you combine the equations, E=hv and c=lambda x v, getting lambda=hc/E. Plug in the values for each constant: (6.626x10^-34 Js)(3.00x10^8 ms^-1)/(2.25x10^-14 J). Finally, you find that the wavelength is 8.83x10^-12 m. Hope that helps!

[Chem_Mod]

Please remember to include the actual question in your post, and not just the problem number.

[Laura Riccardelli]

In the answer to question 1.23 how did you get the equation lambda=(hc)/E from the two equations E=hv and c=lambda?

[Chem_Mod]

Both of the equations have frequency in them: E=hv and c=lambda * v. After you rearrange them you can get v = E/h and v = c/lambda. Then by making two equations equal to each other you get: E/h = c/lambda or lambda = hc/E