Eleven metal chlorides were lit in the presence of methanol as the control and each corresponding flame color was observed 1 1 Essay

Submitted By mickey1121
Words: 3210
Pages: 13

Abstract: Flame spectroscopy is a chemical analysis to determine what elements and how much there are in a sample through the intensity and wavelengths distributed from the light after flaming it. The basic concept is after an electron returns to its ground state from an excited, it releases energy in the form of light (detailed description later on). An application of this atomic emission spectroscopy can be seen in street lights. An electric current is passed through the headlights which excites the electrons to a higher energy level. When it falls back down, light is emitted. For this lab, eleven metal chlorides were lit in the presence of methanol as the control and each corresponding flame color was observed along with the physical properties and residue. For example, BaCl2 is a compound with white opaque solid grains which emits a green flame leaving behind a greenish residue. Unknown compound FT201415 consisting of 4 unknown chlorides was distributed to a group of students. Using the data collected based off the 11 metal chlorides, and comparing it to the test results of the unknown substance, the students concludes that the 4 metal chlorides present are KCl, NaCl, FeCl3, and LiCl. Some major errors include masking and blending where a dominant color stands out and “hides” the colors of the other elements. A way to improve this would be to use inductively coupled plasma (explained later on) to detect wavelengths of light. Another error has to do with inconsistency for the trials. A solution would be to make sure an exact amount of a substance is sin the mixture each time a trial takes place. And lastly, due to the fact that humans can only perceive what they see to a certain extent, they might not be able to detect frequencies which can be resolved by using a spectroscope.

A flame test is a qualitative test in which chemists and scientists use to study color of light through excitation and to determine certain elements within an unknown compound (Flame). To understand why certain compounds produce different colors of flames, on must first understand how the excitation of electrons works. As most electrons within this atom are at its lowest energy level, they are in their ground state. So how can these electrons be bumped up to a higher energy level? There are 2 ways how this can happen. First, the electron absorbs a photon (light particle) with just the right amount of energy to kick it up to a higher quantum shell (Keller). The second way is demonstrated in this lab, and that is adding heat to the electrons (Keller). When heated, they gain energy that is enough to move them to the upper energy level. This theory is can be understood by Bohr’s atomic model of hydrogen. According to Bohr, electrons are in orbits of different energy levels in the atom. The normal energy level an electron occupies is known as the ground state. By absorbing energy, the electron can jump to a higher energy level where it is unstable. For it to return back to its original, the electron needs to release that energy which is a portion of the electromagnetic spectrum. The electromagnetic spectrum is the distribution of electromagnetic radiation with a specific wavelength and frequency. The visible part of the spectrum has colors divided in to 6 sections; red, orange, yellow, green, green and violet. Specifically, the Balmer series, Paschen series, and the Lyman series describe the line emissions of the hydrogen atom. Balmer series states that the spectrum of light for hydrogen produces 4 different wavelengths from the electrons transitioning to the 2nd quantum level. Lyman series is the series of transitions when an electron from the hydrogen atom goes from a quantum level greater or equal to 2 to the 1st quantum level. And finally, the Paschen series describes the transition of the electron from quantum levels greater or equal to 4 to quantum level 3. Bohr says the closer an electron is to the nucleus of an