An x-ray photon of wavelength 0.989 nm strikes a surface. The emitted electron has a kinetic energy of 969 eV. What is the binding energy of the electron in KJ/mol?

My work:

KE = hv - ϕ; hv - KE = ϕ;

c/lambda = v; 3*108 / (.989 / 109) = v = 3.03 * 1017 s-1

hv - KE = ϕ;

(6.626 * 10-34 Js)(3.03 * 1017 s-1) - 969 eV = ϕ

2.007678*10-16 J - 969 eV = ϕ

convert electron volts to joules:

969 eV * ((1.602 * 10-19)J/1eV) = 1.552338 * 10-16 J

2.007678*10-16 J - 1.552338 * 10-16 J = ϕ

ϕ = 4.5534 * 10-17 J

Now convert to KJ/mol: I don't know where to go from here, do I use avogadro's number?


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level 1
· 5y
I think so.

You are watching: What is the binding energy of the electron in kj/mol?

Everything up to that point is for one electron? If you agree, then yes, use Avogadro's number to get to moles.


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level 2
Op · 5y

Nvm_______________________________________________________________________________________

What should that look like, do I divide by avogadros number? I guess I don't understand why you would want the binding energy in mols of electrons. I also don't have an answer key or an example for this problem so I feel naked about it.

So

Convert to KJ:

4.5534 * 10-17 J / 1000 J = 4.5534 * 10-20 KJ

Divide by avogadros number to get KJ per mole?:

4.5534 * 10-20 KJ / 6.022 * 1023 = 7.56127532 * 10-44 KJ/mol = ϕ?

ohh nvm


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level 1
· 5y
Quantum Chemistry
Avogadro's number is in units of mol-1, so multiplying by it will take care of that. Then you divide by 1000 to go from J to kJ. 90% of the way there already. Well done.

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