Flame Tests ABSTRACT

1 Kelsey Strouse Lab Partner: Avery Martin 12/17/12. Flame Tests ABSTRACT : In this Flame test experiment, seven different known solutions and three different unknown solutions were tested in a burner. After several Tests for each solution it was determined that the accepted values for each solution, in order, were: Ba(NO3)2, yellow-green; Cu(NO3)2, green; LiNO3, red;. KNO3, light violet; NaCl, deep/dark yellow; Ca(NO3)2, orange; Sr(NO3)2, bright red. The same amount of Tests for the known solutions was then given for the unknown solutions. It was determined that unknown A was Ba(NO3)2, unknown B was Ca(NO3)2, and unknown C was Sr(NO3)2. INTRODUCTION: Bohr's theory of the atom includes that electrons may only take up certain energy levels. Atoms have the ability, with enough energy, to go to a higher energy level.

2 Atoms also have the ability to go down an energy level by giving off energy. Electromagnetic radiation is a form of energy that consists of waves made up of electric and magnetic fields. Electromagnetic radiation is given off in the form of a photon in the equation E = hv. In this experiment the identity of several unknowns will be determined by the results for the Flame Tests on seven metallic ions. Flame Tests help us produce colors of metallic ions. Loosely-held electrons are excited quickly in a Flame . The color is a combination of wavelengths of each transition and used to identify the ion. PURPOSE: The purpose of this experiment is to determine what colors are characteristics of particular metallic ions by placing the solution in a Flame . PROCEDURE: A well plate was obtained and a marker was used to label seven wells with the names of the known solutions.

3 A dropperful of each known solution was put into its labeled well. Latex gloves were put on. A beaker with about 10ml of M HCL and a nichrome wire loop was obtained. The burner was then lit and the Flame was adjusted to a low setting. For each test, the nichrome wire was clean, so as not to contaminate the solutions. The wire was cleaned by rinsing it with distilled water, using a wash bottle. It was then dipped in the M HCL solution. It was then placed in the burner Flame for a few moments. The color of the clean nichrome was then determined. This was the color seen in all the trials that followed. Sodium had a very strong color that may have affected our other test, so the sodium solution was tested last. The clean nichrome wire was dipped in one solution. The wire was then placed in the burner Flame and observed.

4 The observations were recorded in Data Table 1. The wire was then cleaned and the steps were repeated with the next known solutions until all seven solutions were tested. Three unknowns were then obtained from the instructor. The same steps were repeated for each unknown. Observations were recorded in Data Table 2. The burner was then turned off and the work area was cleaned. Kelsey Strouse Lab Partner: Avery Martin 12/17/13. RESULTS: Data Table 1: Flame Tests of Known Solutions Salt Solution Color BA (NO3)2 Light yellow, yellow, burnt orange, orange, yellow- green Cu (NO3)2 Lime green, green (x3), bright green Li NO3 Magenta/ hot pink, bright pink, red (x2), pink K NO3 Violet/ light lavender, indigo/ purple, indigo, purple, violet Na Cl Bright orange (x3), orange (x2). Ca (NO3)2 Orange, violet, reddish- pink, magenta, red, purple Sr (NO3)2 Dark orange (x2), red orange (x2), orange-green Data Table 2: Flame Tests of Unknown Solutions Unknown Color A Yellow (x2), orange (x2), yellow-green B Reddish orange, orange (x2), violet, reddish pink C Red (x3), orange (x2).

5 Wavelength and Energy Calculation: = c/v; v = c/ ( is wavelength, c is the speed of light and v is frequency). E = hv (E is energy, h is Planck's constant and v is frequency). C = X 108 m/s h = X 10-34 J. Kelsey Strouse Lab Partner: Avery Martin 12/17/13. Lithium has a line spectrum of red at nm or X 10-7 m. The energy of a photon with this wavelength is X 10-19 J. V = X 108 ,/s / X 10-7 m V = X 1014 s E = ( X 10-34 J x s) ( X 1014 s). E = X 10 -19 J. CONCLUSION: The purpose of this experiment was to determine what colors are characteristically particular to certain metallic ions using Flame Tests . The purpose was not fully accomplished because there was a wide range of colors that were observed for each solution during the Flame Tests . After testing the three unknown solutions in the Flame , we were able to find out the names of all three unknown solutions.

6 Unknown A was Ba(NO3)2, unknown B was Ca(NO3)2, and unknown C was Sr(NO3)2. We can see the colors that these solutions during a Flame test because when the solutions are placed in the Flame their loosely held outer electrons of metallic ions become excited and "jump" energy levels. The atoms then emit the visible light as a side effect when the electrons "fall" back down to the lower, stable levels. All of the solutions before placed in the Flame looked the same, except one, so there was no way to tell which solution was which by just looking at them. Each and every line spectrum emitted is unique to each and every solution. There were different colors for each solution because some solutions emitted higher energy photons. Some solutions emitted higher energy photons to give off a color like violet, and others emitted lower energy photons like the color red.

7 DISCUSSION: During the Flame test experiment, many different ranges of colors were observed for each solution. This means between all ten solutions and approximately twenty-five different colors seen, there was room and must have been multiple possible sources of error. The most likely source of error is that there was residue leftover from either the M HCL or one of the other solutions when another solution was being tested. This would have caused errors because the leftover solution from the previous test may emit a stronger color than the solution was supposed to be. If the previous solution or the M HCl was mixed with the solution being tested, the correct color would not be seen. Another possible source of error could be that the solution was not labeled correctly on the well tray.

8 A third possible source of error was that the nichrome loop was placed in a different solution than the one that was meant to be observed. If this error was to occur, the complete incorrect color would be observed. Instead of using burners, the lab could have been done with matches. This would make the experiment Kelsey Strouse Lab Partner: Avery Martin 12/17/13. much more dangerous because the match would be held in a hand or put on a surface that wasn't sanitized and could alter the color of the Flame . Every element has a line spectrum that is unique to that element. A line spectrum can be emitted when an excited electron in that element "falls" down to lower energy levels. When heating up glass, a yellow Flame can be observed if it is given time to get hot. This yellow Flame is observed because glass gives off a extremely strong spectrum which is what is observed in the fire.

9 Metallic salts emit spectrums that consist of a wide range of vivid colors. These colors are used in fireworks for hundreds of years. The Chinese were the first to produce and use these fireworks that are still used today. They also discovered that metallic salts can also be placed in different areas within a firework so that they emit their spectrums at certain points while the firework is going off creating the shows the fireworks put on.