The Pfund series of lines in the emission spectrum of hydrogen corresponds to transitions from higher excited states to the n = 5 orbit. Calculate the wavelength of the second line in the Pfund series to three significant figures. In which region of the spectrum does it lie?

Explanation:

The second line in the Pfund series corresponds to a transition from n = 7 to n = 5.

To calculate the wavelength of the transition, we can use the Rydberg equation:

where

If n₁ = 5 and n₂ = 7

hey there!

mass = 6.75 g

volume =   9 cm³

therefore:

d = mass / volume

d   = 6.75 / 9

d = 0.7 g/cm³

answer b