Mariam S.
asked 09/17/21Pieces of potassium (Φ = 3.68 ×× 10–19 J) and sodium (Φ = 4.41 ×× 10–19 J) metal are exposed to radiation of wavelength 350.0 nm.
Pieces of potassium (Φ = 3.68 ×× 10–19 J) and sodium (Φ = 4.41 ×× 10–19 J) metal are exposed to radiation of wavelength 350.0 nm.
What is the velocity of the electrons from potassium? What is the velocity of the electrons from potassium?
1 Expert Answer

Raphael K. answered 09/17/21
Chemical Engineer with 10+ years tutoring Chemistry.
Pieces of potassium (Φ = 3.68 ×× 10–19 J) and sodium (Φ = 4.41 ×× 10–19 J) metal are exposed to radiation of wavelength 350.0 nm.
What is the velocity of the electrons from potassium? What is the velocity of the electrons from potassium?
Is not hf = φo + EK ... ?
If so, then just replace the kinetic energy with 1/2mv2 and solve for v to find the escape velocity of the electron.
h = plancks const = 6.626 x10-34 J*s
f = frequency in hz which is found using c/λ = f
Electron mass me = 9.109 ×10−31 Kilograms
hf = φo + EK
6.626E-34J*s * (3E8m/s / 350E-9m) = 3.68E-19J + 1/2 * 9.1E-31kg * v2
6.626E-34J*s * 8.57E14 1/s =
5.68E-19 J - 3.68E-19J =
√[2(2E-19) J / 9.1E-31kg] = v
662,993 m/s = v
6.63x105 = v
I could be totally wrong!
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Mariam S.
i meant for what is the velocity of electrons from sodium09/18/21