Chapter 8

Question 1

What determines natural line widths for atomic emission and absorption lines? About how broad are these widths. typically?

Answer 1

T n l w o a e a a a d b l b d t t u p a a t 1-5 n F. The natural line widths of atomic emission and absorption are determined by line broadening due to the uncertainty principle and are typically 10-5 nm FWHH.

Question 2

In a hot flame, the emission intensities of the sodium lines at 589.0 and 589.6 nm are greater in a sample solution that contains KCl than when this compound is absent. Suggest an explanation.

Answer 2

I t p o K, i o s i s b o t h c o e f t i o p. I t a o K, s o t s a a i, w l t a l e i f a N. In the presence of KCl, ionization of sodium is suppressed because of the high concentration of electrons from the ionization of potassium. In the absence of KCl, some of the sodium atoms are ionized, which leads to a lower emission intensity for atomic Na.

Question 3

For Na⁺ and Mg⁺ ions, compare the ratios of the number of ions in the 3p excited state to the number in the ground state in

(a) a natural gas-air flame (1800 K).
(b) a hydrogen-oxygen flame (2950 K).
(c) an inductively coupled plasma source (7250 K).

Answer 3