Chem 109
Energy and Light
Song of the Week: Moonlight Sonata – Ludwig von Beethoven
Equations of Interest:
E = h
ν
c =
λν
E = hc/
λ
People of Interest:
Planck
Einstein
Bohr
De Broglie
Schrödinger
Heisenberg
The light blue glow given off by mercury street lamps has a
wavelength of 436 nm.
What is its frequency?
c =
λν
ν
= c /
λ
= 3.00 x 10
8
m/s / 436 x 10
9
m
= 6.88 x 10
14
Hz
What is the energy in kJ of 1 mole of photos of FM radio waves with
ν
=
109.0 MHz?
E = h
ν
= (6.626 x 10
34
J s)(109.0 x 10
6
Hz) = 7.22 x 10
26
J for one
photon!
6.79 x 10
26
J = 6.79 x 10
29
kJ
x 6.022 x 10
23
/mol = 4.35 x 10
5
kJ/mol
What is the de Broglie wavelength in meters of a pitched baseball with
a mass of 120 g and a speed of 100 mph (44.7 m/s)?
λ
= h/mv
note: h = 6.626 x 10
34
J s = 6.626 x 10
34
kg m
2
/ s
λ
= 6.626 x 10
34
kg m
2
/ s
/ (0.120 kg)(44.7 m/s) = 1.24 x 10
34
m
Calculate the energies of the
n
=1 and
n
=2 states of the hydrogen
atom in kilojoules per mole.
E
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 Spring '08
 MALINA
 Atom, Light, Ludwig von Beethoven, Einstein Bohr De Broglie Schrödinger Heisenberg

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