Crystal Violet Formal Lab Essay

At five minute intervals over the next fifteen minute period, record the color intensity of the solution of each test tube.

And finally into test tube 3, I pipetted 1.0 ml turnip extract and 4.0 ml of water. The contents of test tube 1 was poured into a spectrometer tube and labeled it “B” for blank. “B” tube was now inserted it into the spectrometer. An adjustment to the control knob was made to zero the absorbance reading on the spectrometer since one cannot continue the experiment if the spectrometer is not zeroed. A combination of two people and a stop watch was now needed to not only record the time of the reaction, but to mix the reagents in a precise and accurate manner. As my partner recorded the time, I quickly poured tube 3 into tube 2. I then poured tube 2 into the experiment spectrometer tube labeled “E” and inserted it into the spectrometer. A partner then recorded the absorbance reading for every 20 seconds for a total of 120 seconds. After the experiment, a brown color in the tube should be observed to indicate the reaction was carried out. Using sterile techniques, any excess liquid left was disposed

The product was placed in a Craig tube and several drops of hot (100°C) solvent (50% water, 50% methanol, by volume) was added and heated until all of the crystals dissolved. The Craig tube was plugged and set in an Erlenmeyer flask to cool. Crystallization was induced once the mixture was at room temperature by scratching the inner wall of the tube. It was then placed into an ice bath for ten minutes until crystallization was complete. The tube was then

The product was then suspended in 2 ml of water with a stir rod in a 50 ml Erlenmeyer flask and heated to boiling. Water was added in one milliliter increments until all the product was dissolved (18 ml added total). The saturated solution was allowed to slowly cool, and gradual white crystal formation was observed. Recrystallized product was collected once more by suction filtration with the Hirsch funnel once crystallization ceased. Collected product dried on a watch glass for a week, weighed 0.14 g (1.2 mmol), and the melting point was 139°-141°

Kinetics is the study of the rate of chemical processes. The kinetics of the reaction between crystal violet and NaOH was studied. In order to monitor crystal violet concentration as a function of time, a spectroscopic colorimeter was used. What is the rate law for decolorization of crystal violet? In order to figure this out, the rate of the reaction of crystal violet and sodium hydroxide must be found. In this experiment, the initial goals were to determine the overall rate law for the rate of decolorization of crystal violet in basic solutions as a function of time and to determine the rate law for the reaction including the actual value of k; Rate = k[A]x[B]y. The rate of a reaction was expected to depend on the concentrations

The data gathered and calculated in the experiment accurately portrayed the way the reactions would have taken place. The chloride analysis was a little bit off from other groups due to the fact that our AgCl was in clumps, creating less surface area, thus our product took longer to burn and may not have burned correctly compared to other groups; yet there are several experimental factors that could have caused us to have different results than other groups, i.e. different measurements for samples. Our sources of error could have included eye measurement error, timing of set solutions error, measurement errors, and small calculation errors. Among other variables, the calibration of the analytical balance and spectrophotometer could have

The proof (twice the % alcohol) starts at its maximum and goes down (as the alcohol evaporates). If we start with a high concentration of alcohol, we will get the azeotrope (95% alcohol, 5% water) for a while, then the concentration will decrease.

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.

The values of color absorbance are effective because color absorbance has a linear relationship with concentration values, which in turn, allows us to easily find concentration values for many solutions. Beer’s law describes this phenomenon since the absorbance is directly proportional to concentration. We observed that as the color absorbance increased, the concentration of the FeSCN2+ complex ion increased. This is because as the FeSCN2+ concentration increases, the blood-red color becomes darker due to more presence of the blood-red FeSCN2+ ion. Therefore, the color absorbance increases because there is more blue color absorbed by the darker red color. We then graphed the absorbance and concentration values and created a line of best fit. Using the line of best fit, we were able to predict the equilibrium concentrations of the FeSCN2+ solutions and find the change required to reach equilibrium. Since we already knew the initial concentration of FeSCN2+ and since we already found the equilibrium concentration of FeSCN2+, we can calculate the change in equilibrium. Using this data, we were able to calculate the equilibrium concentration of all of the species in this lab, since we already knew the change from the initial concentration to the equilibrium change. Q is less than K because there was no initial concentration of FeSCN2+, but after the system reached

15) Obtain the boiled chloroplast suspension, mix, and transfer 3 drops to cuvette 4. Immediately cover and mix cuvette 4. Insert it into the spectrophotometer's sample holder, read the percentage transmittance, and record it in Table 4.4. Replace cuvette 4 into the incubation test tube rack. Take and record additional readings at 5, 10, and 15 minutes. Mix the cuvette's contents just prior to each readings. Remember to use cuvtte 1 occasionally to check and adjust the spectrophotometer to 100% transmittance.

The week after, a recrystallization was performed on the previous week’s crude product. The product ethereal solution was first heated on a steam bath until dry. During the heating, a beaker of methanol was collected and also placed on the steam bath. Once the product was dry, it was cooled to room temperature and then placed in an ice-water bath. The now boiling methanol was added to the crude crystals and a recrystallization was performed. Once completed, the now purified product was collected via Buchner vacuum filtration and stored in drawer to dry for a week. Afterwards, a melting point range of the purified product was obtained by using a Mel-temp apparatus. Lastly, an

If the slope of the line to the left of maximum velocity is different from the slope of the line to the right of maximum velocity, explain why this is. What is responsible for these differences in enzyme kinetics?

4. Once the ray goes through and refracts in the oil and comes out to air from the curving side of the cell, record the point the ray comes out by drawing a dot on the paper using the pencil.

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

Alpha amylase converts starch into glucose and when starch is combined with I2KI indicator a dark purple solution forms. As the enzyme breaks down the starch the absorbency will decrease. The absorbency is measured through the spectrophotometer which reads the transmittance of the wavelengths that pass through the solution. In order to determine the optimum temperature for the enzymatic reaction water bath of varying temperatures were made. To