Flame Tests lab
Purpose
Test the different metal salt solutions in a hot flame and observe the characteristic color given off by each excited atom and to identify the metal ion present in one unknown metal salt solution
speed of light
3.00 * 10^8 m/s
planck's constant
6.626 * 10^-34 J*s
Compare the position in the periodic table of each element examined in this experiment to the energy of the photons that are emitted. Do you observe any trends?
As you go down the groups, the amount of energy released increases. There is no consistency as you go across periods (from left to right)
Formula for energy
E=hv
What caused the colors that you observed during this lab? Why were the colors different?
When atoms of elements are heated at high temperatures, they absorb quanta of energy and move up to a higher energy level. They go down when they don't have enough energy to stay in the energy level and release excess energy as a photon of light. The colors were different because it depends on the wave length of the light emitted, and the metal ions emit different amounts of energy and wavelength. The arrangement of the electrons determines how much energy is emitted.
Possible sources of error that could have complicated proper identification of your unknown compounds
Wire may have been contaminated; left wire in flame too long; etc.
Is a flame test a qualitative and quantitative test?
Yes
relationship between wavelength and frequency
c=λv
dependent variable
color of the flame
why do the flames change colors
different wavelengths are created depending on the amount of energy released
When an atom emits energy, the electrons move from an ______ state to their _____________ state and give off _________.
excited; ground; energy
copper (II)
green
When an atom absorbs energy, the electrons move from their _______ state to an _________ state.
ground; excited
potassium
lavender/pink
Independent variable
metal used
wire used
nichrome wire
Calcium
orange
sodium
orange
lithium
red
strontium
red
barium
yellow-green