Photons, wavelengths, and ionization energy

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SUMMARY

The discussion centers on calculating the wavelength of a photon required to ionize lithium (Li) with an ionization energy of 520 kJ/mol. The calculation involves converting the energy from kJ to joules per photon, using Planck's constant to find the frequency, and then determining the wavelength. The final result is 230 nm, which falls within the ultraviolet (UV) portion of the electromagnetic spectrum. The calculations and equations used in the process are confirmed to be correct.

PREREQUISITES
  • Understanding of ionization energy and its units (kJ/mol)
  • Familiarity with Planck's constant (6.626 x 10^-34 J/s)
  • Knowledge of the speed of light (3 x 10^8 m/s)
  • Basic principles of electromagnetic spectrum, particularly ultraviolet rays
NEXT STEPS
  • Study the relationship between energy, frequency, and wavelength in electromagnetic radiation
  • Learn about ionization energies of other elements and their implications in chemistry
  • Explore the properties and applications of ultraviolet radiation in various fields
  • Investigate the use of Planck's equation in different contexts of quantum mechanics
USEFUL FOR

Chemistry students, physics enthusiasts, and educators looking to deepen their understanding of photon energy calculations and the electromagnetic spectrum.

confusedbyphysics
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This is a post-lab question for my chemistry lab but it is kind of physics too so I thought I'd post it here (the other sciences sections don't much response).. It's confusing because the questions are supposed to go along with what we are learning in the chemistry lecture, but we're behind in the lecture, so I'm trying to teach myself how to do this since we haven't learned it yet!

Here's the problem:

"The ionization energy of Li is 520 kJ/electron mole. What is the wavelength of nm of a photon having sufficient energy to remove an electron from Li? In what portion of the electromagnetic spectrum would you find such a photon?"

My work:

520 kJ = 520000 J

520000 J/mol X 1 mol / 6.02 X 10^23 photons = 8.6379 X 10^-19 J / photons

Energy = h (constant) X v (frequency)

v = E/h

v = (8.6379 X 10^-19 J/photons) / (6.626 X 10 ^-34 J/s)

v = 1.3036 X 10 15 /s

wavelength (w) = speed of light (c)/ v

w = (3 X 10^8 m/s) / (1.3036 X 10^15)

w = 2.301 m /photon X 10^9 nm/m = 230 nm

230 nm = ultraviolent rays

Does this look right? If someone could help me Id soooo appreciate it! (I need to make sure I did this right or I'll miss the next problem too because they're related)
 
Physics news on Phys.org
Looks good ... equations used correctly.
I didn't check your calculator punching,
but your final answer is about right.
 

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