Using Spectrophotometer to measure the concentration of compounds Essay Example For Students

Using Spectrophotometer to measure the concentration of compounds Essay The spectrophotometer can mensurate the strength of light absorbed indirectly by the solutes in solution because each solution has its ain characteristic soaking up movables. The spectrophotometer can be used to mensurate the concentration of compounds in a certain solution. Distinguishing compounds is another utilizations of spectrophotometer.It plants by analysing the form of wavelengths absorbed by the sample.. The optical density can be calculated utilizing: Beer-Lambert Law, Absorbance, A= IÂ »bc where, IÂ » is the molar absorbtivity coefficient in L mol-1 cm-1 B is the way length ( in centimeter ) of the cuvette in which the sample is contained degree Celsius is the concentration of compound in solution, in mol LAÂ ­AÂ ­-1 If two compounds are present in a solution, the entire optical density of the solution is the amount of the two separate parts harmonizing to the expression Atotal = K1C1+K2C2 where, C1 and C2 are the concentrations of bromophenol blue and methyl orange severally in the mixture K1 and K2 are the molar absorbtivity coefficient of each compound of the several wavelength Material Methyl orange solution, bromophenol bluish solution, micropipette, tip droplet, mixture of bromophenol blue and methyl orange, trial tubings. Method Part 1: Determination of Amax of bromophenol blue A cuvette with distilled H2O was placed into the spectrophotometer. The wavelength input is set to 470 nanometer. Auto zero button was pressed to put the optical density into nothing. The space is removed. Optical density of bromophenol blue is read at different wavelengths. After a certain wavelength is tested against bromophenol blue, the spectrophotometer is set clean utilizing distilled H2O. A new wavelength is set to obtain a new optical density value. A graph of soaking up spectrum was plotted and the wavelength with maximal optical density reading was determined from the graph. Part 2: The consequence of concentration of bromophenol blue on optical density The distilled H2O and mixture of distilled H2O with bromophenol blue are prepared harmonizing Table 1.2 and the contents of each tubing are assorted utilizing vortex sociable. The spectrophotometer is set clean utilizing cuvette with distilled H2O. Wavelength of the spectrophotometer was set at Amax wavelength of bromophenol blue and the optical density reading is recorded. The mixture of tubing 1 should be holding a zero optical density. Concentration of bromophenol blue in tube 1-6 was calculated utilizing information in table 1.2. Standard concentration curve was plotted and the molar absorbtivity coefficient ( in unit L mg-1 cm-1 ) of the expression from Beer-Lambert Law was calculated utilizing the standard concentration curve. Part 3: Determination of the concentration of the bromophenol bluish solution of unknown concentration The optical density reading is set clean utilizing a cuvette of distilled H2O. The optical densities of the two bromophenol blue of unknown concentrations were measured at the Amaxof bromophenol blue. The concentration of the two unknown were determined from the graph 2 and besides by utilizing Beer-Lambert Law. Part 4: Determination of consequence of concentration on optical density of methyl orange solutions Mixtures of distilled and methyl orange are prepared harmonizing Table 1.2b The contents of each tubing is assorted utilizing vortex sociable. The spectrophotometer is set to the Amax wavelength of methyl orange which is 460nm. The optical density reading of tube 1-6 is measured utilizing the same cuvette you used for tubing 7. The optical density readings is recorded in Table 1.2b. The concentration of the methyl orange solutions in tubes 1-6 are calculated. Graph of standard concentration curve of optical density versus concentration of methyl orange is plotted. The molar absorbtivity coefficient of methyl orange at 460nm ( in unit L mg-1cm-1 ) is calculated utilizing standard concentration curve from measure 7. Part 5: Determination of concentrations of two different solutes, bromophenol blue and methyl orange, in mixture C The spectrophotometer is set to a wavelength of 460nm Amax of methyl orange. The spectrophotometer is set clean by pressing the ( auto-zero ) button. The optical density of the bromophenol bluish solutions in tubes 1-6 in Table 1.2a is measured at the Amax of methyl orange. The consequences is recorded in table 1.2a A graph of standard concentration curve of bromophenol blue at Amax of methyl orange. Molar absorbtivity coefficient of bromophenol blue at 460nm is determined. The spectrophotometer is set space once more utilizing distilled H2O. Optical density of methyl orange solutions in tubes 1-6 in Table 1.2b at the Amax of bromophenol blue. The consequences is recorded in Table 1.2b A graph of standard concentration curve of methyl orange at Amax of bromophenol blue is plotted. The molar absorbtivity coefficient of methyl orange at Amax of bromophenol blue is calculated. The optical density of mixture C incorporating bromophenol blue and methyl orange ( tube C ) is measured at the wavelength of Amax of bromophenol blue and Amax of methyl orange ( 460nm ) The consequences is recorded in Table 1.3 Consequences Part 1: Determination of Amax of bromophenol blue Table 1.1: Optical density of bromophenol blue in different wavelengths Wavelength ( nanometer ) Optical density 470 0.093 500 0.143 530 0.282 560 0.535 590 0.981 620 0.211 650 0.013 680 0.002 From the graph 1, the highest extremum is found to be at the wavelength 590nm. Therefore, the Amax of bromophenol blue is in wavelength of 590nm. Part 2: The consequence of concentration of bromophenol blue on optical density Table 1.2: The optical density values of bromophenol blue in different concentration for the wavelength of 590nm and 460nm. Tube 1 2 3 4 5 6 A Bacillus Distilled H2O ( milliliter ) 2.5 2.0 1.5 1.0 0.5 0.0 Bromophenol blue 10 mg/L ( milliliter ) 0.0 0.5 1.0 1.5 2.0 2.5 Concentration of Bromophenol blue ( mg/L ) 0.0 2.0 4.0 6.0 8.0 10.0 Optical density in 590nm 0.000 0.271 0.459 0.690 0.907 1.091 0.361 0.235 Optical density in 460nm 0.000 0.010 0.026 0.038 0.055 0.079 Beer-Lambert Law, Optical density, A= IÂ »bc is in the signifier of y=mx ( consecutive line expression ) where, B is the way length ( in centimeter ) of the cuvette in which the sample is contained ( 1cm ) Analysis Of Scarlet Letter EssayPart 3 The optical density of the two bromophenol bluish solutions ( Tube A A ; B ) of unknown concentration at the Amax of bromophenol blue ( 590nm ) were measured. The concentrations of the two unknown solutions were determined utilizing two methods. The first method used was extrapolating the graph 2 while the 2nd method used was utilizing the expression of Beer-Lambert Law to cipher the concentrations of the two unknown solutions. From the first method, the concentration for the Tube A bromophenol blue is 3.15 mg/L while the concentration of Tube B bromophenol blue is 2.05 mg/L. While, from the 2nd method utilizing the Beer-Lambert Law, A = IÂ »bc, the concentration of Tube A bromophenol blue obtained is 3.195 mg/L while the concentration of Tube B bromophenol blue is 2.080 mg/L. Concentration consequence for each unknown obtained utilizing two different methods mentioned above give different consequence. The difference in consequences might due to random mistakes in the experiment. The random mistake that might happen was that the surface of the cuvette was non clear or due some fragment of mixture is non absolutely mixed in the solution. Fingerprints might be printed on the clear surface of the cuvette therefore impacting the supposed visible radiation sum base on balls through.This will impact the optical density reading of bromophenol blue. This random mistake can be reduced by guaranting that the surface of the cuvette was wiped with paper towel before puting it into the spectrophotometer. Furthermore, the orientation of the cuvette may be inserted wrongly into the spectrophotometer when the optical density reading is taken. Part 4 The peak optical density of methyl orange is at 460nm. The optical density of methyl orange addition with the concentration of methyl orange in the mixtures. The optical density novice from 0.000 til 0.814. A graph of optical density against concentration of methyl orange. A consecutive line go throughing through beginning is obtained. This showed that the concentration of methyl orange increased straight relative to the optical density of light with certain wavelength. Hence, this portion of experiment obeyed the Law of Beer- Lambert. Somehow, non all point is inside the consecutive line. So, there is some random mistake occur when transporting out this experiment. The random mistake includes, the mixture is non absolutely assorted.Furthermore, there might be fingerprint left on the wall of cuvette.This affect the sum of light go throughing through the solution.There might be caused by hapless pippeting technique that caused inaccuracy in optical density reading of methyl orange. The picks of taking wavelength will impact the sensitiveness and truth of the analysis. Therefore impacting the optical density of solution or Beer- Lambert Law is non obeyed. The molar absorbtivity coefficient calculated is 0.082 L mg-1cm-1. Part 5 The experiment shows addition in optical density when concentration bromophenol bluish increased.Bromophenol bluish solutions are tested utilizing Amax of methyl orange- 460nm of visible radiation. The optical density addition from 0.000 to 0.079 of absorbance.A graph of optical density of visible radiation against concentrations of bromophenol blue is plotted.A consecutive line go throughing through the beginning is plotted. This showed that optical density addition straight relative to the concentrations of bromophenol blue. The graph shows scattered point around the consecutive line. This indicated random mistakes occur in the experiment. Some illustrations of random mistake are hapless pippeting technique that may do inaccuracy in mensurating volune of bromophenol blue. Another portion of the experiment in portion 5 is to change the concentration of methyl orange and trial it utilizing Amax of bromophenol bluish -590 nanometer of visible radiation. The trial shows that there is addition of sum of optical density as the concentration increased. A graph of optical density against concentration of methyl orange is plotted. A consecutive line go throughing through beginning is obtained. This meant that optical density addition proportional to concentration of methyl orange. This shows that it obey the jurisprudence of Beer-Lambert. All points are in the graph. Therefore, there is minimal mistake occurred when the experiment is carried out. The concentration of bromophenol blue and methyl orange in the two mixture solutions of tubing C was determined utilizing the expression, Atotal = K1C1+K2C2. By work outing coincident equation, the concentration of bromophenol blue in the mixture C was 6.841 mg/L and the concentration for methyl orange in the mixture was found to be 4.876 mg/L. Decision Part 1, the Amax of bromophenol blue is at the wavelength of 590nm. Part 2, the optical density of visible radiation is straight relative to the concentration of bromophenol blue as the standard concentration curve of optical density versus concentration of bromophenol shows a consecutive line go throughing through the beginning. Molar absorbtivity coefficient of bromophenol blue in 590nm is 0.113 L mg-1cm-1. Part 3, two methods were used to find the concentration of the two terra incognitas ( tube A A ; B ) . By utilizing insertion of the graph, the concentration of bromophenol blue in Tube A is 3.15 mg/L and the concentration of bromophenol blue in Tube B is 2.05 mg/L. Mean while, utilizing the expression of Beer Lambert Law, the concentration of bromophenol blue in Tube A is 3.195 mg/L and the concentration of bromophenol blue in Tube B is 2.080 mg/L. Part 4, the optical density of visible radiation is straight relative to the concentration of methyl orange as the standard concentration curve of optical density against concentration of methyl orange shows a consecutive line go throughing through the beginning. Molar absorbtivity coefficient of methyl orange in 460nm is 0.082 Fifty mg-1 cm-1. Part 5, the molar absorbtivity coefficient of methyl orange in Amax of bromophenol blue is 0.005L mg-1cm-1.Molar absorbtivity coefficient of bromophenol blue in Amax of methyl orange is 0.0069 Fifty mg-1 cm-1. The concentration of bromophenol blue in Tube C is 6.841 mg/L and the concentration of methyl orange in Tube C is 4.876 mg/L.