Laboratory Report : Flame Colors of Metals Essay
Laboratory Report : Flame Colors of Metals
The experiment about flame color of metals demonstrates how electrons jump into their excitedstate from their ground state as it came in contact with heat. As it return to its lower energy state,it emits the absorbed energy in the form of light. A platinum or nichrome wire was dipped into aconcentrated HCL and was heated to clean it. The wire was dipped into different salt solutionsand heated in order to determine the metallic ion’s color and wavelength. Metal ions emitting aviolet-colored flame has the largest amount of energy while those that emit red-colored flamehave the least amount of energy.
An atom is the smallest particle of an element, which can exist and still have theproperties of the elementElectrons determine the chemical properties of atoms. The electrons in an atom exist inlayers called shells or energy levels. The negatively charged particles of an electron are kept inorbit in the energy levels. Normally, atoms do not emit radiation but there are ways of causingradiation to be emitted. The simplest of these is to heat the atoms. When an atom is heated, itabsorbs energy causing its electrons to get excited to positions of higher potential energy farther away from the nucleus. At this state, the atom becomes unstable. When an electron goes back toits ground state, it radiates the absorbed energy in the form of light, which has a characteristicwavelength. This is the basis of the flame test used to identify the element. The quantity of energyabsorbed will account for the presence of a spectral line. The emission spectrum may be used todetect the presence of an element in both qualitative and quantitative way. Elements may oftenbe recognized by the color they impart to a flame.
Materials And Methods
A platinum or nichrome wire was dipped into a concentrated HCL. The wire was heatedinto the flames hottest region until there was no visible color. The cleaning procedure wasrepeated as necessary. On a watch glass, a few crystals of CaCl2 were added on to 2 or 3 dropsof distilled water. It was stirred until it was dissolved. The clean wire was dipped into a saltsolution and was returned to the hottest part. The flame color was then noted. Using other salts,namely KCl, NaCl, CuCl2, LiCl, SrCl; the process was repeated.
Data and Discussions
As the salt solutions were exposed to the hottest region of the flame, the atoms of thefollowing metal ions jumped into their excited states and immediately emitted different kinds of color according to their own characteristic line spectrum.For this experiment, necessary computations were needed such as the energy,frequency of light, and wavelength. Below are the formulae and references used in theexperiment.
Equation 1: E=hc/ ΛEquation 2: E=hv
E-energy of light
C-speed of light (3.00 x108m/s)
H-Planck’s constant (6.63 x10-34J-s)
V-frequency of light
The table below shows the complete data of results after doing the experiment andsolving for the necessary values.
In this experiment, we were able to analyze metallic ions in salts with the use of flametest. We were also able to determine the metal that emitted the largest amount of energy which isPotassium ( K) and the metal that emitted the least amount of energy which is Lithium (Li) andStrontium (Sr).
Therefore I conclude The metal ions are the ones giving you the color in a flame test, lame tests could be misleading if one metal has a much brighter flame than another metal ion. For example Sodium has a bright yellow flame that might mask a faint color from another element.
University/College: University of California
Type of paper: Thesis/Dissertation Chapter
Date: 3 February 2017
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