Visible Light Lab Report

The purpose of this experiment is to determine the maximum absorbance of fast green, and the chlorophylls, also in the case of fast green create a concentration curve to determine an unknown substance. Each test will use the spectrophotometer.

I found out that both of my experiments were off by 0.46 and 0.13 but were remotely

The procedures for experiment A, B, and C all start the same. The first step is to put on goggles and get the data collection device set properly. The labquest needs to be plugged into the colorimeter accurately so that a click is heard when putting it in. The labquest needs to be reading digitally and the colorimeter needs to be set to 635 nm. Then shake the chloroplast solution and take a clean cuvette and fill it with 3 mL of distilled water, 3 drops of the chloroplast solution, and cap it. This is used as a blank to calibrate your labquest. Double check that the labquest is reading absorbance, this assures that the colorimeter is plugged into the labquest accurately. Insert the blank into the colorimeter and hit the calibration button. Take out the blank and empty it. The labquest is now set to experiment with. Make sure that the heat bank is set in front of the lamp and that the lamp is on. The cuvette must be placed on the opposite side of the heat bank in the path of light in the box so that no other light can interfere with the experiment.

5. The degree of precision was to 3 significant figures obtained with the spectrophotometer. The major source of error in our experiment was not calibrating the spectrophotometer with distilled water.

The dyes in the laboratory experiment are made of numerous colors, mainly red and blue, the spectra from each of the dyes corresponded to the wavelengths obtained from each of dye i.e. 620 nm for red and 450 nm for blue.

Therefore, a theoretical uncertainty value that accommodates both uncertainties of the measurement and the equipment is calculated. The theoretical uncertainty calculation is primarily based on the propagation of error formula. The theoretical uncertainty calculation is as follows.

The objective in Lab 8 is to measure wavelength of five emission lines of light and a laser beam through the principle of light interference.

This experiment was design to find the amount of copper in a penny using a visible spectroscopy. We achieved this by combining .89 to .93 of Cu(NO3)2*2.5H2O to a 25mL volumetric flask and filling the flask to about half full with deionized water, swirl, then fill to the line with more deionized water. After, fill a 25mL burret with Cu2+ stock, with this add .5, 1, 1.5, and 2 mL of the stock to four different volumetric flask, add 2mL of 15 M NH3 from the burret to each flask and swirl, then fill to the line with deionized water. First, calibrate the spectrophotometer then; enter samples of each of the four samples in the spectrophotometer to test the absorbency. For the penny stock solution, use a 500 mL filter flask with about 250 mL of 1 M NaOH, place a rubber stopper to the top and connect a inverted long stem funnel to it using tygon tubing, and place a 125 mL flask below it. Turn on the water aspirator, place the penny in the 125 mL flask, measure out 20-25 mL of 8 M nitric acid in a 50 mL graduated cylinder, and then slowly add it. It should take about 5-10 minutes for the penny to dissolve.

The absorbances for the Cary 60 were more accurate than the absorbances for the Ocean Optics when compared against accepted absorbance values (Appendix C) for the absorbance accuracy and linearity portion of the experiment (tables 2 and 3). These differences can be attributed to stray light and background corrections. Because the Ocean Optics sample holder is exposed to outside light, it is more prone to scattered light error, which inflates the absorbance expected. The Cary 60 does not suffer from this issue because it is in a dark environment. Also, as previously discussed, the Cary 60 corrects for background whereas the Ocean Optics instrument does not.

This was because we lacked a level to keep the apparatus at 90 degrees to the ground and it was difficult to measure the length of the rope whilst tying it up to the stand at different heights. It was a combination of these factors as well as my partner’s focus on the experiments that likely caused the error. This is because during the experiment I would count the number of swings and my partner was supposed to time the length of swings. However, During the experiment my partner got distracted on multiple occasions including on trial 2 for 87.5 cm. This is likely what made the error so much larger than for the other trials. However, it was likely my measuring of the length of rope and the angle of swing which caused the smaller errors as it was difficult to measure the angle by eye and measure the length of rope whilst tying

3. The spectrophotometer was set at 420nm. Distilled water was also used as the ‘blank’.

Possible ways to fix these errors could be making sure that when reading the graduated cylinder, it is read at eye level and the bend, or meniscus, is what is read. If the highest point is read the data would be incorrect because the water is holding on to the sides of the

One reason the experimental value was different from the accepted value is because the light ray from the ray box had a width, causing the marking to not be perfectly centered in the ray. Another reason the experimental value was different from the accepted value is because the semi-circular container was not secured allowing movement between angles. The change of location of the container would alter the angles

The results obtained were to some degree surprising. I was surprised about the amount of light detected by the light metre when it was placed 10cm away from the light box. I presumed a substantial amount of light would be detected, however I thought the brightness of the light would be closer to 200 instead of 162.6. Conversely, I wasn’t surprised about the relationship between the distance and the light intensity; I knew that the intensity of the light would be greater, the closer to the light box the light was analysed.

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