Question

Suppose a sodium atom has a de Broglie wavelength of 1.02 picometer. At what linear speed is it moving, to three significant digits? (The molar mass of Na is 22.990 g/mol.)

Answer 1

Solution:

1.Find the mass of the sodium atom:

m= M/N_a = 22.99/6.02*10²³ = 3.819*10^-23g = 3.819*10^-26kg

2.By the ratio of De Broglie:

α = h/mu; u = h/mα = 6.626*10^-34/3.819*10^-26*1.02*10^-12 = 17010 m/s = 1.70*10⁴m/s

Answer: 1.70*10⁴ m/s