Question

Potassium is determined by flame emission spectrometry using a lithium internal standard. The following data was obtained for standard solutions of KCl and an unknown containing a constant known amount of Licl as the internal standard. All were corrected for background by subtracting the intensity of a blank. Concentration of K (ppm) Intensity of K Emission Intensity of Li Emission 1.0 10.0 10.0 2.0 15.3 7.5 34.7 7.5 65.2 10.0 95.8 10.0 20.0 110.2 5.8 Unknown 47.3 9.1 5.0 68 8.5 Show that the relationship of the emission line intensity to concentration is a linear function. Determine the concentration of the unknown potassium solution.

Answer 1

Conc of K emmision(ppm) Iof Kemmision 10 15.3 34.7 65.2 95.8 110.2 Plot of C vs 1 for K Intensity of K y = 5.6113x + 12.647 10 15 20 25 C(ppm)

We of can k confirm by plotting vs intensilit yj of.k NA concentration emision. Thus, the linear relation - ship is y = 5.6113x + 12.647 y = intensity of K emission x= concentration of k. The unknown concentration of K. can be calulated x= Y-12.647. 5.6113 47.3 – 12647 5.6113 = 47.3 emission for unknown) = 6.175