Error Analysis Lab

How do you know that it was not the non-metal ion whose colour you observed? (Hint:look closely at the names of the solutions that you tested). the non- metal ion which was chloride never changed and stayed the same for all the solutions, but the metal ions were all different for each solution. 3a. You were assigned two household items to test - what were common (non scientific) names of these items?

The dark, navy blue colored graph represented the absorbance curve for the S1 sample. The red colored graph represented the absorbance curve for the S2 sample. The green colored graph represented the absorbance curve for the P1 sample. The purple colored graph represented the absorbance curve for the P2 sample. The gaps between the P2 curve was due to the oversaturation that led to the inconclusive spectrophotometer readings. The blue colored graph represented the absorbance curve for the P1 low salt sample. The orange colored graph represented the absorbance curve for the P2 low salt sample. The light blue colored graph represented the absorbance curve for the P1 medium salt sample. The light pink colored graph represented the absorbance curve for the P2 medium salt sample. The light green colored graph represented the absorbance curve for the P1 high salt sample. The light purple colored graph represented the absorbance curve for the P2 high salt

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.

This light is known as the spectrum emission color of an element which can also be used to identify an element as well as determine the energy that is given off. In this lab we used this information to identify three unknown substances and determine if the energy given off was high or low. In order to conduct this lab we had to take a known substance for example Copper Chloride (CuCl) and use a splint to put the substance over a bunsen burner. We then recorded the frequency, color of the flame, and the spectrum emission line by using spectroscopes, which diffracts light.

When you use a spectrophotometer you should not set the wavelength of light to be the same color of the solution. This is because if you set the wavelength to be the same color of the solution then no light will be absorbed. The reason why no light will be absorbed is because the color you see is the wavelength of light that is being reflected so you must set the wavelength to be the complementary color. The wavelength of light that was chosen for the lab was 450nm which coincides with a very dark blue color. The reason why choosing a dark blue makes the most sense for this experiment is because the color of the FeSCN2+ ion was blood red.

2- It is impossible to identify all element with the naked eye because they don’t release enough energy, therefore the color is not as visible. Besides, not all elements give a light that it is in the visible part of the spectrum, so we need to use a prism.

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.

Next, we took initial absorbance readings in the Spec20 at an absorbance rate of 600 nm as well as an initial color reading. Then placed one sample under red, blue, green, or white light illuminators, and one sample in the dark. The cuvette placed under the white light acted as our positive control, and the cuvette placed in the dark acted as our negative control. We took absorbance readings of each cuvette every 5 minutes until we had four readings. After the fourth and final absorbance reading, we also took a final color reading.

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.

Figure 3 plots the relative overall response of the Spectronic 20, the relative response of a phototube, and the relative lamp intensities as a function of wavelength. The Spectronic 20 response curve shows a maximum relative response at 512 nm with a transmittance of 88.3%. The phototube response curve shows a maximum relative response at 400 nm with a transmittance of 100%. This means the light source used in Part A emitted green light stronger than any other wavelengths and the phototube

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

The objective of this lab was to determine the concentration of iron (Fe+2) in an unknown substance using a spectrophotometer. Spectrophotometry is a process that uses a sample solution to determine how much light a chemical substance absorbs by measuring the intensity of a beam of light passing through the solution. Every substance transmits light over a specific wavelength range, so spectrophotometry is often used to measure the amount of a known chemical in an unknown substance. White light, or sunlight, is shot through the opening slit of a cuvette containing the substance. The reflection of the substance by a

The color of the light depends on the difference in the two energy levels. We can see only those transitions that correspond to a visible wavelength. Every element

The determination of the amount of copper in a penny involves multiple scientific concepts that are extremely important. First, the experiment involves a redox reaction of Copper and Zinc. Copper and zinc are both components of a penny and the oxidation reaction utilizes nitric acid, a very strong oxidizing agent, in order to oxidize both copper and zinc. The reaction generates a highly toxic, brown gas which is nitrogen dioxide (NO2), but more importantly, it results in the complex ions of copper and zinc. The complex ion generated of copper is Cu(H2O)42+ and has a dark blue hue while the complex ion generated of zinc is Zn(H2O)42+ and does not have a distinctive color. Essentially, a complex ion is formed by having a central metal ion that has formed covalent bonds with multiple ligands, which are simply anions. Furthermore, the Beer-Lambert Law establishes a relationship between light absorption and solution concentration by claiming that the concentration of a certain solution is directly proportionate to the total amount of light energy that the compound present in the solution can absorb (The Beer-Lambert). A spectrophotometer can be utilized to measure how much light energy of a certain chosen wavelength is absorbed by a particular sample.

The goal of the lab was to discover the concentration of phosphate in various colas in order to help with a project for a major cola company. Before we could accomplish this final goal, a Spec 20 was used to test three colors of food colorings. A Spec 20 is an instrument used to “measure the intensity of a light beam before and after it passes through a sample and compares these two intensities” (What does a Spectronic 20 measure). The instrument is able to measure the percent transmittance and absorbance of a given sample. It works by taking light of various wavelengths and passing them through a monochromator. A monochromator is a device that transmits a wavelength of light. The machine diffracts the wavelengths. The sample that is placed in a small container, called a cuvette, absorbs various wavelengths. This depends on the particular sampled being tested. The amount of light absorbed is projected by the machine on a screen, in our case, a digital screen (How Does a Spectronic 20 work?). By doing the lab with the food colorings, we were able to properly learn how to use the Spec 20 and also learn the relationship between absorbance and transmittance. Percent transmittance is the amount of light entering the sample in the cuvette divided by the amount of light leaving the sample, multiplied by 100. This percent can then be converted to absorbance, which is a measure of the capacity of a substance to absorb light of a specified wavelength (Absorbance). It is converted by