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Experiment (4) Flame Photometric Analysis of Sodium Objective: 1- To learn about the function of a flam photometer. 2- To produce a calibration curve for the determination of concentration. 3- To determine the Na concentration in an unknown sample. Theory: Flame photometry is also known as atomic emission spectrometry. ** A flame photometer instrument is extremely simple where the sample in solution is aspirated through an aspirator or nebulizer into the flame which is usually a propane / air fuel. The sample matrix evaporates followed by atomization of the sample. Atoms present in the high temperature zone of the flame are excited to higher energy levels by absorbing energy from the flame. As excited atoms return to the ground state, they emit radiation in definite wavelength depending on the energy level from which each atom drops. This gives rise to a line spectrum. Flame photometry is good only for elements that are easily excited and do not require very high temperatures (Na, K, Li, Ca) are the most widely determined atoms by this technique).

Eng. Raeda Tashtoush

Eng. Raeda Tashtoush

The intensity of the light emitted could be described by the Scheibe-Lomakin equation:

n=1 then: I=K×C That is the intensity of emitted light is directly related to the concentration of the sample.

Procedure: 1- Prepare stock solution of Sodium chloride solution NaCl (1000 PPm) 2- Prepare five standard solution each time 10, 20, 30, 40, and 50 mL of the stock 1000 ppm sodium chloride solution into 100-mL volumetric flasks, respectively. 3- Spray sample solution into the flame for three times and record Intensity of light emission.

Results Concentration of NaCl (ppm) 0 200 400 600 800 1000 Tap water Healthy water

Eng. Raeda Tashtoush

I% 0 42 64 113 125 185 40 10

Calculations: 1- calculate the concentration of Na+. CNaCl *( M.wt Na \ 𝑀.𝑤𝑡𝑁𝑎𝐶𝑙) = CNa 2- Plot a calibration curve the galvanometer reading against Na+ concentration. 3- Determine Na+ concentration of the unknown sample. 4- Determine the proportionality constant (k).

Eng. Raeda Tashtoush...