The aim of this investigation was to find how changes to concentration and temperature affect the refractive index of salt solution (sodium chloride: NaCl). Seven different concentrations (0%, 5%, 10%, 15%, 20%, 25%, and 30%) of salt solutions were prepared. The salt solutions of each concentration were then brought to the five different temperatures: 10˚C, 30˚C, 50˚C, 70˚C, and 90˚C. At each of these temperatures, the distance deviated by the incident ray was measured by passing a laser beam of wavelength 663nm through a hollow prism filled with the different salt solutions. Refractive index of the salt solutions were derived using the angle of minimum deviation which was calculated from the distance deviated by the incident ray. Five trials were conducted to increase the reliability of the results. This experiment replicates the functions of a refractometer.
In this year of 2014, Gautum Magu is a Year 12 student at John Paul College. This Extended Essay is part of his International Baccalaureate Program.