Chemistry: Flame Test Lab
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In the flame test lab, the flame test was performed to excite the electrons in the samples and observe the color of the flame. The flame emits a color because each element has an exactly defined emission spectrum, which one can use to identify them. For example, NaCl was highlighter yellow, Sr(NO3)2 was sun orange, CuCl2 was turquoise, LiCl was neon red, KCl was solar flare yellow, and BaCl2 was Voldemort green. Introduction-
In Bohr’s model of the atom, electrons travel around the nucleus in an orbit. The concentric circles in his model represent the energy levels. Electrons can jump from energy level to energy level and absorb or emit light energy when they jump from one energy level to another.1 By placing compounds into a flame, electrons can be induced to absorb energy and jump to an excited energy state. The electrons then return to their ground state by emitting a photon of light. The amount of energy in the photon determines its color; red for the lowest energy of visible light, increasing energy through the rainbow of orange, yellow, green, blue, indigo, and finally violet for the highest energy of visible light. Photons outside the visible spectrum may also be emitted, but cannot be seen. One can view the emission spectrum of colors all at once with the naked eye. It will appear to be one color, which is carefully described.
A flame test is a procedure used to test for the presence of certain metals in a chemical compounds. When the compound was excited by heating it in a flame, the metal ions began to emit light. Due to the emission spectrum of the element, the compound turned the flame a certain color. In this lab, the color of the flame test of many compounds was recorded by holding them over an ignited Bunsen burner. The hypothesis was that the separate colors of the emission spectra would be observed as the compound burned. Materials-
Goggles, Bunsen burner, beaker with deionized water, wooden splints soaked in water, sodium chloride (NaCl), strontium nitrate (Sr(NO3)2), copper chloride (CuCl2), lithium chloride (LiCl), potassium chloride (KCl), barium chloride (BaCl2), calcium chloride (CaCl2), and blue glass. Procedure-
To start, safety goggles were put on. Seven wooden splints that were soaked in distilled water were then placed into a 250 ml beaker half-full with deionized water to continue soaking. Six weighing dishes were then labeled “NaCl”, “Sr(NO3)2”, “CuCl2”, “LiCl”, ” KCl”, and “BaCl2” were obtained. Each contained a scoop full of each metallic solid in the corresponding weighing dish. After this, the Bunsen burner was carefully lit. The soaked end of one of the metallic splints was then dipped in one of the metallic salts. The “dipped” wooden splint was then placed into the flame and the color was observed. If any of the solid fell on the lab bench or Bunsen burner the test had to be repeated with the same splint and salt. The wooden splint was then immersed in the “rinse water” to fully extinguish it, as well as the match. The splint and match were thrown in the trash after this. The observations for the flame color produced by the metallic salt were recorded in the data table. The previous steps were repeated for the other metallic steps and the observations for the flame color produced by each metallic salt were also recorded in the data table. After the lab was finished, the area was cleaned up, everything was put away, and hands were washed before leaving.
In the lab, sodium chloride burned a highlighter yellow color and the internet says it burns a yellow color. Strontium nitrate was observed to be burning a sun orange color but the web says it burns red. The copper chloride burned a turquoise color in the lab whereas the internet says it burns blue. The World Wide Web also says that lithium chloride burns red but in the lab it was observed as a neon red color. Potassium chloride burned a solar flare yellow color but the internet said it was purple.2 The barium chloride produced a Voldemort green color when placed in the flame but the web says it burns light green. Finally, calcium chloride burned a starburst orange color but the internet says it burns a brick red color. 3 The unknown metallic salt was sun orange, just like Sr(NO3)2, which means these were the same compounds. Conclusion-
In the lab, each compound was held in a flame and the color of the flame was then observed. NaCl was highlighter yellow, Sr(NO3)2 was sun orange, CuCl2 was turquoise, LiCl was neon red, KCl was solar flare yellow, and BaCl2 was Voldemort green. The hypothesis was correct because each compound placed in the flame, did in fact, change the color of the flame. In lab, two errors were possibly made. The first was that there was cross contamination of the metallic salts, which could affect the color of the flame. The next error was that the compounds had been sitting out all day. That would give time for other things to get into them and also alter the color of the flame observed.