Assuming the rotation of a diatomic molecule in the J10 stat

Assuming the rotation of a diatomic molecule in the J=10 state may be approximated by classical mechanics, calculate how many revolutions per second 23Na35Cl makes in the J=10 rotational state. The rotational constant for 23Na35Cl is 0.21681 cm-1 .

Solution

The rotational constant for ²³Na³⁵Cl = 0.21681 cm-1 = 6500 MHz

v = B J(J+1) , E units depends on B ( rotational const) , here B= 6500 Mhz , hence vwill be in MHz i.e v will be frequency ,

v = 6500 x10 ( 10+1) = 715000 Mhz = 7.15 x 10^5 Mhz = 7.15 x 10^11 Hz

each Hz = number of rotations per sec

hence for each second number of rotations = 7.15 x 10^11