Achieve Homework #2, Question #12

[trishaferrer]

Hi! Can someone help me with this? Thanks!

[katrinahuwang_1L]

For the first part of the question, use the equation, E = hc/lambda to get the energy of the 1064 nm light. Then convert the energy into electron volts. 1 eV = 1.602 x 10^-19 J. Since the electron affinity of thulium is the energy difference between the incident radiation from the laser and the experimentally measured energy of the ejected electrons, subtract 0.137 eV from the calculated value to get the answer.

For the second part of the question, electron affinity can then be converted to units of kilojoules per mole to get your answer.

[Phoebe Ko 3E]

Since the question asks for the electron affinity, you would need to convert the wavelength of the incident radiation into energy using the E=hc/lambda equation. Then, you would convert the result in eV to Joules with the constant 1 eV = 1.602*10^-19 J. To calculate the electron affinity of thulium, you would subtract the given energy of ejected electron (0.103 eV) from the result. The second part of the question asks you to convert the calculated electron affinity into kJ/mol. To do so, you would apply the constant again and remember to use the Avogadro's constant (6.02214*10^23 atom/mol) as well since part 2 is asking for an answer in mol, not atom.

[Jose Angelo Grajeda 2D]

I would convert the λ = 1064 nm into 1.064*10^-6 m, then use C=λv to find frequency (v), which is 2.8195*10¹⁴ Hz. Then use the E=hv equation to find energy in Joules, and convert Joules into eV (1 eV = 1.602*10^-19 J, so divide!). Using this value (1.166 eV), I'd subtract the energy of the ejected electrons (0.137 eV) to get 1.029 eV (per atom).

Then, using dimensional analysis, convert 1.029 eV/atom into kJ/mol. This can be done by multiplying by 1.602*10^-19 J, dividing by 1000 J (to get kJ on top), and finally multiplying by Avogadro's Number (6.02*10²³ atoms) to get mol on the bottom. The result is 99.255 kJ/mol. Hope this helps!