How do Solutes Affect a Solutions Angle Of Refraction?By, Prajwal Keranahalli
BackgroundSnells Law describes the physics of refraction. The index of refraction of a liquid depends on the density of the liquid. Dissolving sugar in water results in a solution with density greater than that of water alone. Since sugar water is more dense than plain water, sugar water should have a higher index of refraction than plain water.
More BackgroundDensity of the solutes that I am going to use:Baking Soda: 2.20 g/cm3Salt: 2.16 g/cm3Sugar: 1.5620 g/cm3
HypothesisIf the solute is baking soda, then the index of refraction of the solution will be greater, because baking soda has more density than salt and sugar, and greater density results in a greater angle of refraction.
Independent Variable/ Dependant Variable/ ControlsIndependent Variable: The SoluteDependant Variable: The Index of RefractionControl:The Index of Refraction in water with no solute(0.4)Controls:The Type of ContainerThe Type of WaterThe Type of LightThe Amount of Each Solute
Materials A Laser Pointer 2, 1”×3” pieces of glass Cardboard Measuring Cup 100 mL of Salt, Sugar, and Baking Soda A Graphing Calculator Electrical Tape Epoxy glue Tape 400 mL of Water Glass Cutter 12in. of String Tape measure Graph Paper Tooth Picks
Procedures1. Cut your 1”×3” glass piece into 3 equal parts using a glass cutter. Complete this step with adult supervision.2. Arrange the 3 pieces of glass to form an equilateral triangular prism. Glue it together using epoxy glue. Allow it to set.3. Glue the prism on top of another 1”×3” glass piece. Allow it to set.4. Take your laser and shine it perpendicular to the wall, place the empty prism in front of the beam (the beam should not be diverted) and record where the beam hits the prism and wall.5. Make 3 solutions by mixing 50 mL water with 0.25 teaspoons of Salt, Sugar, and Baking Soda.6. Pour one of your solutions into the prism until it is almost full.7. Shine the laser through the prism and record where the light hits the prism and wall.8. Repeat steps 1-7 with the other solutions
To Find the Index of Refraction1. Measure the distances of X and L (indicated on the diagram), it will define the measure of minimum deviation which will be used to find the index of refraction.2. Also find the distance between segment CA3. Use X and L to find the arctangent. Opposite/Adjacent=X/L=measure of angle of minimum deviation=Ømd4. Plug the angle of minimum deviation into the equation: 2.00056sin(0.5(Ømd+60)) this will give you the index of refraction.
Measurements Sugar Salt Baking SodaX 134 mm. 220.2621 164.0914 mm. mm.L 274 mm. 272 mm. 263 mm.Segment 312 mm. 364 mm. 310 mm.CAØmd 28.57 ° 41.65° 31.96°
Sugar Baking Soda SaltWater Where Laser hit the Wall No Solution
Data TableType of Solutions Index of RefractionSolute inthe Trail 1 Trail 2 Trail 3 AverageSolutionSugar 0.6 0.6 0.5 0.56Baking 1.8 1.9 1.8 1.83SodaSalt 1.1 1 1.2 1.1
Graph Type of Solute V.S. the Solutions Index of Refraction 2 1.5Solutions Index ofRefraction (AVG.) Sugar Baking Soda 1 Salt Water 0.5 0 Type of Solute in the Solution
ConclusionSolutions with higher density had greater index ofrefraction. My hypothesis was supported throughthe data. Baking soda which had the most densityhad more refraction than salt and sugar. It had arefraction of 1.83 while salt was 1.1 and sugarwas 0.56. And the refraction of all the soluteswas greater than the refraction water which was0.4. So it is proven that an increase in densitydoes result in a greater index of refraction. Ialready knew that substances refract light butthis experiment explained to me why thishappens and why some substances refract morelight than others. I could have improved myexperiment by constantly replacing my lasersbatteries so that I so that is could get moreconsistent measurements. A good follow upexperiment would be to test how differentconcentrations of solute in a solution would affectindex of refraction.
Math Behind the Experiment 1 X Angle of Minimum Deviation L
Math Behind the Experiment 2 Segment CA XUsed for Sine Used for Arctangent L