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THE EFFECT OF THE EFFECT OF TEMPERATURETEMPERATURE AND AND CONCENTRATIONCONCENTRATION ON THE ON THE REFRACTIVE REFRACTIVE

INDEX INDEX OF OF SALT SOLUTIONSSALT SOLUTIONS AND ITS AND ITS DETERMINATIONDETERMINATION

USING USING DIFFRACTION GRATING DIFFRACTION GRATING METHODMETHOD

ANDO, AILENEANDO, AILENEPACHEJO, ROMELPACHEJO, ROMEL

The Effect Of The Effect Of TemperatureTemperature And And ConcentrationConcentration On The On The Refractive Refractive Index Index Of Of Salt SolutionsSalt Solutions And Its Determination Using And Its Determination Using Diffraction Diffraction Grating Grating MethodMethod

RationaleRationale

Theoretical Theoretical BackgroundBackgroundStatement of the Statement of the ProblemProblemSignificance of the Significance of the StudyStudy

Research MethodologyResearch Methodology

CC


Used to identify salts precipitated from body fluids and measure relative amounts of sodium and potassium chloride in the body Increasing the concentration of salt in water affects the density and atomic interaction of water Increment increase in the refractive index per unit change in its concentration is yet to be determined Temperature affects the density of the liquid Improvised refractometer (Samson and Ricarte, 2009) adopting minimum angle deviation method The nature of the prism could lead to error in the experiment (oracle, n.D.)

RationaleRationaleRationaleRationale


RefractionRefraction

Theoretical Theoretical BackgroundBackgroundTheoretical Theoretical BackgroundBackground

Happens when there is a change in the speed light as it goes from one transparent material to another Causes the ray to deviate from its incident direction The change in direction at the interface of two materials depends on the angle at which the ray strikes the surface that separates the two media


Snell’s Law of Refraction


nn11 is the refractive index of the first mediumθθ11 is the measure of the angle of incidencenn22 is the refractive index of the second mediumθθ22 is the measure of the angle of refraction

n1sinθ1= n2sinθ2


Refractive Index


Ratio of the speed of light in each medium where the light travels Used to calculate the focusing power of lenses, the dispersive power of prisms, identify a particular substance, confirm its purity, and measure its concentration refractive index of liquids is dependent on several factors, such as density, concentration of solute, temperature, pressure, and wavelength of light


Temperature and Refractive Index


Temperature affects the density of the liquid Refractive index is proportional to the square roots of electrical permittivity and magnetic permeability Refractive index does not have a simple relationship with temperature (Zimmerman, 2008)


Concentration and Refractive Index


Concentration is the amount of solute present in a given amount of solution Percent by mass is the simplest quantitative expression in measuring the solute concentration of a solution (Brown et al., 2004) Increasing the concentration of salt in water affects the density and atomic interaction of water The change in refractive index will be on the order of hundredths, resulting in a change in refractive angle of over a degree. (Yap, 2004).


Diffraction Grating (Nave, no date)


An optical component used to spatially separate polychromatic light (white light) into its constituent optical frequencies Consists of glass substrate with a series of parallel, equispaced lines on the front surface of the glass


Diffraction Grating


The diffraction pattern produced by the grating is described by

m λ = d sin αmm is the order number λλ is a selected wavelengthdd is the spacing of the slitsαα is the angle of incidence of light


Diffraction Grating Method



Related Studies


There is a linear increase in the index of refraction as solute concentration is increased. However, as temperature of the solution increased with constant solute concentration, index of refraction tends to decrease. The more molecules added into a solution (and the bigger the molecules are) the more of a chance the light has of hitting the molecules. This slows down the light as it goes through absorption and reemission, causing an increase in the index of refraction”. (Pham, 2008).


Related Studies


Subedi, D.P., Adhikari et al., in 2006, studied the temperature and concentration dependence of refractive index of liquids using minimum angle deviation method. They found out the linear dependence of concentration on its indices of refraction. They were also able to determine the temperature coefficient of water the range 30°C- 70°C

Grzegorz F. Wojewoda, (no date) used diffraction grating and polarization method in measuring the index of refraction of water. He realized that the refractive index does not deviate largely from the theoretical value. Frederick A. Osborn and Horace H. Lester (1912) also used the same method for determining index of refraction.

CC


This study aims to investigate the effect of temperature and concentration on the refractive index of salt solution and its determination using diffraction grating method. Specifically, it intends to:establish the relationship between refractive index and various salt concentration establish the relationship between refractive index and temperaturedetermine the refractive index increment of the solution for a specific change in its concentrationverify the validity of the locally-made instrument in measuring the index of refraction of a solutionverify the validity of the proposed method in measuring index of refraction of salt solutions

Statement of the Statement of the ProblemProblemStatement of the Statement of the ProblemProblem

CC


Medical ProfessionalsMedical ProfessionalsThrough this research, doctors can identify salts precipitated

from body fluids and measure relative amounts of sodium and potassium chloride which indicates whether or not a person has toxemia. Shipping industryShipping industry

Knowing the index of refraction of a body of water can indicate the salinity of water which can be one of the factors in the construction of a wharf. BiologistsBiologists

They will know the tonicity of a cell and the direction of the movement of its particles between it and its environment.

Significance of the Significance of the StudyStudySignificance of the Significance of the StudyStudy

CC


Science CommunityScience CommunityThey are presented an alternative method of measuring the

index of refraction of a solution. High School LaboratoriesHigh School Laboratories

High school students can perform experiment that measures the refractive index of a liquid at a lesser cost. Teachers and StudentsTeachers and Students

The teachers can demonstrate another way of measuring index of refraction for the benefit of high school students for this can equip them with much knowledge of the related concepts used in this study. Researchers Researchers This will enhance their analytical and critical thinking skills while performing this study.

Significance of the Significance of the StudyStudySignificance of the Significance of the StudyStudy


Research Research MethodologyMethodologyResearch Research MethodologyMethodology

Cutting tracing paper, sticking to one external wall of a vessel

Cutting tracing paper, sticking to one external wall of a vessel

Stick diffraction grating to opposite wall

Stick diffraction grating to opposite wall

Place laser next to diffraction grating

Place laser next to diffraction grating

Diffraction Grating Method Set-up


Research Research MethodologyMethodologyResearch Research MethodologyMethodology Solution Preparation

Masses of 200, 400, 600, 800, 1000 grams

of salt are weighed

Masses of 200, 400, 600, 800, 1000 grams

of salt are weighed

Each sample will be put inside an empty and clean beakers.

Each sample will be put inside an empty and clean beakers.

Each beakerwill be filled with distilled water up to the 1000- mL mark.

Each beakerwill be filled with distilled water up to the 1000- mL mark.

Mixing of each salt sample with water in

beakers

Mixing of each salt sample with water in

beakers

Computation of Concentration

(percent by mass)

Computation of Concentration

(percent by mass)Labeling of

BeakersLabeling of

Beakers

Exposure of the beakers to 3

different settings (hot, cold, room)

Exposure of the beakers to 3

different settings (hot, cold, room)


Research Research MethodologyMethodologyResearch Research MethodologyMethodologyMeasuring index of refraction through diffraction grating method

Room temperature to be constant (20 – 25 oC)

Room temperature to be constant (20 – 25 oC)

Pouring of salt concentrations with temperature range of 75°C - 80°C into the

vessel

Pouring of salt concentrations with temperature range of 75°C - 80°C into the

vessel

Switching on the laser, marking of the zeroth order

fringe and the two first order fringe

Switching on the laser, marking of the zeroth order

fringe and the two first order fringe

Changing height of laser and marking of

fringes

Changing height of laser and marking of

fringes

Repeat previous steps for salt solution with

different temperature ranges

Repeat previous steps for salt solution with

different temperature ranges

Recording of date on table 1

Recording of date on table 1

Calculation of Refractive Index

Calculation of Refractive Index


Research Research MethodologyMethodologyResearch Research MethodologyMethodology

Getting a sample for each salt concentration with temperature

range of 75°C - 80°C

Getting a sample for each salt concentration with temperature

range of 75°C - 80°C

Measure refractive index using improvised instrument and Abbe

Refractometer

Measure refractive index using improvised instrument and Abbe

Refractometer

Repeat previous steps for salt solution with different temperature ranges

Repeat previous steps for salt solution with different temperature ranges

Measuring index of refraction through improvised instrument and Abbe Refractometer

Date post:	03-Jun-2015
Category:	Technology
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