ANALYTICAL cHEMISTRY - Iv

MSCM302

Experiment 4

Aim of the Experiment

Determination of sodium (Na+) and potassium (K+) by flame photometry.

Principle

  • The principle of flame photometer is based on the measurement of the emitted light intensity when a metal is introduced into the flame. The wavelength of the color gives information about the element and the color of the flame gives information about the amount of the element present in the sample.

  • Flame photometry is one of the branches of atomic absorption spectroscopy. It is also known as flame emission spectroscopy. Currently, it has become a necessary tool in the field of analytical chemistry.

  • Flame photometer can be used to determine the concentration of certain metal ions like sodium, potassium, lithium, calcium and cesium etc. In flame photometer spectra the metal ions are used in the form of atoms. The International Union of Pure and Applied Chemistry (IUPAC) Committee on Spectroscopic Nomenclature has named this technique as flame atomic emission spectrometry (FAES).

Apparatus required

Borosil beakers (100 ml) 20 Nos., Standard measuring flasks (100 ml) 2 Nos., Flame photometer.

Chemicals required

NaCl, KCl, Conductivity water, etc.

Preparation of reagents

Standard solutions:

  • (Sodium): 2.542 g sodium chloride in 1 L de-ionised water in a graduated flask 1 ml ≡ 1.0000 mg (Given).

  • (Potassium): Dissolve 1.906 g of potassium chloride in 1 litre deionised water in a graduated flask. 1 ml ≡ 1.0000 mg (Given).

Working standard:

  • (Sodium): Place 2 ml of 1000 ppm standard solution of sodium into 100 ml measuring flask and dilute it 100 ml by conductivity water. Concentration of this solution will be 20 ppm.

  • (Potassium): Place 2 ml of 1000 ppm standard solution of sodium into 100 ml measuring flask and dilute it 100 ml by conductivity water. Concentration of this solution will be 20 ppm.

Procedure

  • Prepare different sets of 2, 4, 6, 8, 10, and 12 ppm sodium solution by placing 2, 4, 6, 8, 10, and 12 ml of the working standard solution into clean and dry beakers and diluting each to 20 ml with de-ionised water.

  • Similarly prepare different sets of 4, 6, 8, 10, 12, and 14 ppm potassium solution by placing 4, 6, 8, 10, 12, and 14 ml of the working standard solutions into clean and dry beakers and diluting each to 20 ml with de-ionised water.

  • Adjust the oxidizing flame of flame photometer. Select the filter and adjust zero reading with conductivity water and set 100 emittance with 20 ppm working standard solution.

  • Measure emittance of the sample solution and determine its concentration from the standard curve.

To determine the Na & K ion using Flame Photometer_1.mp4
To determine the Na & K ion using Flame Photometer_2.mp4

Observation Table

Result

  1. Amount of sodium in the given sample is _________ mg.

  2. Amount of potassium in the given sample is __________ mg.

Reference Material

  1. G H Jeffery, J Bassett, J Mendham and R C Denney, Vogel's Textbook of Quantitative Chemical Analysis, 5th Edition

  2. S. Suzanne Nielsen, Food analysis, 4th Edition

Questions


Developed by

Dr. Viraj Bhanvadia,

Assistant Professor, Chemistry,

viraj.bhanvadia@gsfcuniversity.ac.in