The Concentration Of A Solute

• 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.

From this graph and chart we can see that the higher the concentration the higher the absorbance, all the different concentrations were tested at the same wavelength (625nm). Also we can determine our unknown substances concentration by using the absorbance we got for it. The red dot on the graph followed by the line towards the horizontal axis indicates that the concentration of fast green was 34% or 5.1x10-3.

Colorimetric assay is a process determining the concentration of a chemical element or compound in a solution

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.

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)

By first measuring the pH levels of solution A through E with a pH meter, it gives a numeric reading to ph balance to a solution. Next, add in a natural indicator called anthocyanin made from the pigment from a red cabbage into each solution and mixed it until there is a distinct color and recorded on the chart. Finally, by looking at the result of the pH reading level that

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

When the beetroot sample is heated for a longer period of time, it is exposed to the vigorous and frequent vibrating molecules for a longer duration. This further disrupts the cell membranes making them more fragile, thus more pigment will leak out into the external solution. With more leakage of the betacyanin pigment, the % transmittance should be lower, indicating that the % of light that is able to pass through the beetroot solution should be less as duration heated increases.

The purpose of this experiment was to determine the pKa of the bromothymol blue (indicator) through absorption spectroscopy. Bromothymol blue being a monoprotic acid base indicator, displays different colors at different pH because of the differences in the ratio of the conjugated acid and base form. The fraction of conjugate acid and base was interpolated for the solutions through the acquired absorbance spectrum of the bromothymol blue at various pH. The rearranged form of Henderson Hasselbalch equation was graphed as a function of pH to determine the pKa of the indicator.

The aim of this investigation was to determine the effect of ethanol on the membrane permeability using Beta vulgaris. Beta vulgaris contains red pigments called betalain sequestered in vacuoles. The cell membrane is generally impermeable to betalain as this pigment is relatively large and cannot pass through the membrane by diffusion. (123HelpMe.com, 2015) However, by increasing the permeability of the cell membrane, betalain can leach out of the cell and colour the liquid red. The colour intensity of the solution due to leakage of betalain is proportional to the membrane permeability. To quantify the colour intensity, the light absorbance of the solutions containing a Beta vulgaris cube were measured by a spectrophotometer. These measurements were used to analyse the membrane permeability. (Flinders University, 2015)

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

For generating valuable data with a desired accuracy and to quantify concentration of the constituents present in the samples being analyzed.