The average speed of a helium atom at 25 degrees C
is 1.23 x103 m/s. What is the average wave-
length of a helium atom at this temperature?
A) 8.11 x 10^-11 m
B) 2.03 x10^-11m
C) 7.43 x 10^-15 m
D) 4.06 x 10^-11 m
E) 4.15 x 10^-12 m
2006-09-10 16:11:29 · 1 answers · asked by ruby 2 in Education & Reference ➔ Homework Help
de Broglie's Wavelength formula for an atomic particle:
λ = h/p
λ = wavelength
h = Planck's Constant
p = momentum of the object
λ = 6.6260693 * 10^-34 Nms / p
p = mv
m = .004002602 kg (atomic weight of Helium) / 6.0221415 * 10^23 (Avogadro's #) = 6.646476 * 10 ^-27 kg for 1 atom of Helium
p = 6.646476 * 10 ^-27 kg * 1.23 * 10^3 m/s
p = 8.175 * 10^-24 kg m/s
λ = 6.6260693 * 10^-34 Nms / p
λ = 6.6260693 * 10^-34 Nms / 8.175 * 10^-24 Ns
λ = 8.11 10^-11 (solution, option A)
2006-09-11 01:31:45 · answer #1 · answered by ³√carthagebrujah 6 · 0⤊ 0⤋