Questions On The Quantification Of Light Absorption And Transmittance As A Function Of A Solution

The concentrations and absorbances of the red and blue dyes were used to find the concentration of the purple dyes. From the graph of the blue dye, the linear equation for absorbance was y = mx + b. From that formula came the equation y = 7.915 x 104 (x) + 0.02489, where y represents absorbance, m is slope, x is concentration/molarity, and b is the constant/y-intercept. The same set up was performed for the red dye, but the equation produced was y = 1.045 x 104 (x) +.001298. The equations found when graphing absorbance vs. concentration were used to find the concentration of the purple dyes. The absorbance for purple dye 3 on the red wavelength of 470 nm equaled 0.149 and 0.818 for the blue wavelength of 635 nm. For purple dye 1

• Secondly, we also used a colorimeter which is extremely accurate when it comes to measuring the percentage light transmission. As it measures the percentage light transmission as a numerical value.

Spectroscopy is the study of light. A spectrophotometer is a machine used to determine the absorbance of light at any given wavelength. It does this by using a source of white light through a prism, which gives multiple wavelengths that can be individually focused (Ayyagari and Nigam, 2007). Substances are put into cuvettes that are glass or quartz containers that light can easily travel through. The light that is being focused travels through the substance gets absorbed by the

A spectrophotometer’s purpose is to use colors of the light spectrum to determine the concentration of light absorbing molecules in a solution. (p.59) In this particular lab, our mission was to determine the protein concentration and the standard curve of the unknown sample of BSA. This, by preparing five dilutions of the unknown solution of BSA together with other known concentrations, and then experimenting by observing how the concentrations were passed through the spectrophotometer. The outcome resolved in the absorption levels being decreased, and this

Time) because it had a correlation closest to 1. All three orders were graphed and a linear regression was used to see which graphed order was closest to 1. The order was determined by comparing the concentration and time to the mathematical predictions made using the integrated rate laws. Analyzing each graph and finding each correlation helped determine which graph was closest to 1. The more concentrated a solution is, the higher the absorbance of that solution. This is due to Beer’s Law. The law measures the absorbance of a solution by determining how much light passes through a solution. As the concentration of a solution increases, fewer wavelengths of light are able to pass through the concentrated solution. The absorbance at 60 seconds was 0.573 (Figure 1: Table1). To calculate the concentration (molarity), the Beer’s Law equation was used, Abs = slope(m)+b. Plugging in what is known into the Beer’s Law equation resulted in 0.573 = 3.172e+004 + 0, where the concentration is determined by M = 0.573-0/ 3.172e+004. So, the concentration at 60 seconds using the equation (M = 0.573-0 / 3.172e+004) was 1.824e-5 M. The 1st order graph resulted in k=0.006152 (Figure 1: Graph 1). Other groups also resulted in their decolorization of CV to be the 1st rate

Scientists use an instrument called a spectrometer to quantitatively determine the amount of light absorbed by a solution. The primary inner parts of a typical spectrometer are described below. The spectrometer has a light source that emits white light containing a vast mixture of different wavelengths of electromagnetic radiation. The wavelength of interest is then selected using a monochromator (“mono” meaning one and “chromate” meaning color) and an additional exit slit. The separation of white light into different colors (wavelengths) is known as diffraction. The selected light then reaches the sample and depending on how the light interacts with the chemical compound of interest, some of the light is absorbed and some passes straight through. By comparing the amount of light entering the sample (P0) with the amount of light reaching the detector (P), the spectrometer is able to tell how much light is absorbed by the sample.

An experiment was done to determine the concentration of Allura Red in a commercially available beverage, Gatorade. This was done by using the colorimeter, the absorbance of five Allura Red solutions were measured. The graph obtained demonstrated a linear relationship and the equation obtained yielded a concentration of 1.9910-6M.

The Beers Law calibration experiment used many concentrations of crystal violet solutions. Each of these solutions were test and analyzed in order to determine the absorbance of each concentration The results were than graphed and produced a slope of 1.00E05 with an intercept of -2.21E-02.

MANUAL Q5: What color of light is being absorbed by the sample solution? How is that color related to the color of the solution?

6. A spectrophotometer would definitely be useful in experiments involving the measurement of concentration that produces color, since the color absorbance can be used to find concentration. One experiment involving a spectrophotometer could be finding the molarity of a blue Copper(II) sulfate solution. The wavelength could be set to red, and then the absorbance values can be correlated to the molarity of Copper(II)

A = Absorbance difference  = Molar extinction coefficient C = Concentration L = Path length

Once a light beam shines through the flame, the atoms absorb some of the light. It is then detected, recorded and compared to a series of standard solutions. In the absorption spectrum, the absorbed light show up as black gaps. These distinctive gaps indicate the difference in energy levels for a particular element. If this can be compared to the concentration of its standard solution, then it can form a calibration curve.

A spectrophotometer is an instrument which measures the amount of light of a specified wavelength which passes through a medium. This instrument is usually used for the measurement of reflectance of solutions. Light is separate into different wavelengths and is being passed through the sample solution. The sample solution will have its own wavelength and will absorb a certain amount of light. The higher the molecular concentration, the higher the absorbance value.

You may ask what line spectrum is and why it is used by scientists or even how it is used in The Flame Test Lab. Scientists use the Flame Test and line spectrum to help them determine what an unknown element is. They can use the observation of the color and lines produced in a line spectrum by a gaseous state element to help them decide what the element is. Flame tests can be used to help the scientist determine what an element is in its solid form, by placing it in a flame and observing what color is produced. Wavelengths of color are emitted because of electrons becoming excited and jumping to higher sub-levels and then jumping back down to lower sub-levels.

concentration, record the absorbance readings at a fixed wavelength, and plot the absorbance vs. concentration data. The wavelength of 520 nm was selected for experiment Part