NAME:___________________________________________DATE:_____________PERIOD:_______
LAB: Flame Test for Metallic Ions
Background: When a substance is heated in a flame, the substance’s electrons absorb energy from
the flame and move from a ground state electron configuration to an excited state electron
configuration. The amount of energy absorbed by the electron going from ground state to excited
state is equal to the amount of energy released when the electron goes from excited state back to
ground state. The electron takes in thermal energy and then emits the energy as electromagnetic
radiation (light). According to Einstein and Planck, the frequency of the light emitted is related to the
energy by the following equation: E = h f.
Objective: To observe various colors of light emitted when electrons of metallic elements move from
an excited state (higher energy) to a stable state (lower energy).
Pre-Lab Questions: Answered and turned in? __________
Procedure:
1) Pick up the pre-soaked wooden splint with crucible tongs.
2) Place the splint into the flame and observe, identify, and record the color.
a. Do not let the wood catch on fire.
3) When finished dunk the wooden splint into a 250mL beaker filled with water.
4) Repeat this procedure until each compound is tested.
5) Throw away the splints in the trash after they have cooled in the water.
The ions will come from either nitrate compounds or chloride compounds. For example lithium nitrate
or lithium chloride would be the source of the lithium ion.
Data:
Ion to be tested
Color in flame
Wavelength for that color
**do not use the same # twice**
Lithium ion
Sodium ion
Potassium ion
Strontium ion
Calcium ion
Barium ion
Copper II ion
Red 700 nm Orange 650 nm Yellow 600 nm Green 550 nm
Blue 500 nm Indigo 450 nm Violet 400 nm
NAME:___________________________________________DATE:_____________PERIOD:_______
Calculations:
Use the following wavelengths for the colors seen to calculate for frequency and energy.
ħ =6.6 x 10-34J * sec 1 x 109 nm = 1 m
Red 700 nm Orange 650 nm Yellow 600 nm Green 550 nm
Blue 500 nm Indigo 450 nm Violet 400 nm
**Convert your wavelength to meters first**
Ion tested
Wavelength (m)
Frequency (Hz)
Energy (J)
Lithium
Sodium
Potassium
Strontium
Calcium
Barium
Copper
Conclusion:
1) Which color shows the highest exchange of energy? _____________________
2) Which color shows the highest frequency? _____________________________
3) Which color shows the shortest wavelength? ___________________________
4) Which color shows the longest wavelength? ____________________________
5) Which color shows the lowest frequency? ______________________________
6) Give the colors of visible light from lowest to highest energy.
7)
_____________________________________________________________
Give the colors of the visible spectrum from longest wavelength to shortest
wavelength._____________________________________________________
8)
A firework contains copper chloride and strontium sulfate. What colors will this explosive
produce? ________________________________________________
9)
Why do people, clothing and other objects look different under mercury vapor lights and sodium
vapor street lights?
__________________________________________________________________
10) Suggest a reason why each element emits a unique color spectrum.
__________________________________________________________