Answer:
1.24
⋅
10
15
Hz
Explanation:
Your strategy here will be to
use Avogadro's number to find the energy needed to ionize one atom of sodium
use the Planck - Einstein equation to find the frequency of light that corresponds to that specific energy
So, you know that the energy needed to ionize sodium is equal to
496 kJ/mol
. As you know, one mole of any element contains exactly
6.022
⋅
10
23
atoms of that element - this is known as Avogadro's number.
In your case, the energy needed to ionize one atom of sodium will be equal to
496
kJ
mol
⋅
10
3
J
1
kJ
⋅
1
mol
6.022
⋅
10
23
atoms
=
8.236
⋅
10
−
19
J/atom
The relationship that exists between energy and frequency is described by the Planck - Einstein equation
E
=
h
⋅
ν
, where
E
- the energy of the wave
h
- Planck's constant, equal to
6.626
⋅
10
−
34
J s
ν
- the frequency of the wave
Plug in your values and solve for
ν
, the frequency of light needed to ionize a sodium atom
Explanation:
