16-Flame Test Lab

Flame Test Lab
Various metals produce a distinct characteristic light due to its unique electron configuration. This
characteristic light is the basis for the chemical test known as a flame test, where a scientist determines a
substance’s composition based on the color it produces in a flame. The metal in each compound you are
testing is italicized in your data table.
Learning Target
Students will analyze atomic spectra.
Keep all flammable material away from Bunsen burner.
Avoid getting any chemical on skin; wash immediately if spills occur.
Part A – Flame Test
1. Light your Bunsen burner and adjust until you get a small blue flame.
2. Remove the splint from the beaker filled with water and dip the wood splint into the sample of the solid at the
3. Place your wood splint into the flame and record your observation of the color – make good observations. Don’t
just record that it’s red; record things like ‘firetruck red’. BE SPECIFIC! No two elements should be recorded as
the exact same color.
4. Repeat the procedure at each station to obtain the color for each of the metals in the compounds.
Table 1 – Flame Test
sodium nitrate
lithium nitrate
potassium nitrate
copper nitrate
calcium nitrate
strontium nitrate
unknown nitrate
Part B – Spectroscope
1. Obtain a spectroscope, and use it to look at the fluorescent lights in the hallway. Look through it while it’s pointed
towards the light source. Make sure the numbers are right side up when you are looking through the
spectroscope. Draw the lines you see; make note of the color of each line for the light source.
2. Repeat step 16 with the elemental samples located in the classroom. Pick either the hydrogen sample or the
helium sample.
3. Go to a window where you can observe the natural light outside. If the sun is shining, do NOT look directly at the
sun. Instead, find an open spot in the sky. This spectrum will look different; describe what you see.
Table 2 – Spectroscope
Light Source
Color the light appears
with the naked eye
Drawings/Observations of Spectrum with Wavelength
----------l--------------------l--------------------l--------------------l---------400 nm
500 nm
600 nm
700 nm
Elemental Sample
Read the introduction and then answer each of the following questions in complete sentences.
1. Look at the names of the compounds you tested. All of them include the name ‘nitrate’. Do you think the nitrate
portion of the compound emits the observed colors when energized? Explain.
2. What color did the unknown produced? What compound was in your unknown? Reference your data to support
your answer.
3. Why do the chemicals have to be heated in the flame before the colored light is emitted?
4. Flame tests are good to use because of the small amount of the compound necessary to obtain a flame color.
Based on your data and experiences, explain 2 chemical reasons why a flame test may NOT give an accurate
account for the composition of a compound. Be sure to explain WHY your reasons would cause a problem.
5. If milk was boiling on a gas stove and it boiled over, what color flame would you expect to see? Explain your
answer using your data in your answer.
6. During a flood, the labels from three bottles of chemicals were lost. The three unlabeled bottles of white solids
were known to contain the following: strontium nitrate, ammonium nitrate and potassium nitrate. Explain how
you could easily test the substances and re-label the three bottles. Reference your data in your answer. (Hint:
Ammonium ions do not provide a distinctive flame color.)
7. The spectrometer is used to separate out the different wavelengths of light in part B of the lab. What was used to
separate out the wavelengths when Bohr was examining the hydrogen line-emission spectrum?
8. Explain what was occurring that caused the colors you saw during the flame test. Use the following six
vocabulary words from the chapter correctly in your explanation, and UNDERLINE each vocabulary word:
absorption [absorb, absorbing, etc]
excited state
emission [emit, emitting, etc]
ground state