Flame Test Lab The Identification of an Element · 1. To perform a flame test, use the tweezers to obtain one wood splint from the test tube which has been soaking in salt solution

RAHSI Revised 4 August 2010 Modified from Rachel Stein, Flame Test lab, Castle Park High School, Chula Vista Ferreira, et.al, Case Report: Analytical Electron Microscopy of Lung Granulomas Associated with Exposure to Coating Materials Carried Carried Glass Wool Fibers, EHP, Vol 118 (2), Feb 2010

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Flame Test Lab: The Identification of an Element

By placing atoms of a metal into a flame, electrons absorb energy and jump to an

excited energy state, a quantum jump. Then, they return to their ground (original)

state by emitting a photon of light (the law of conservation of energy indicates that

the photon emitted will contain the same amount of energy as that absorbed in the

quantum jump). The amount of energy in the photon determines its color; red for the

lowest energy of visible light, increasing energy through the rainbow of orange-

yellow-green-blue-indigo and violet which has the highest energy of visible light.

Photons outside the visible spectrum may also be emitted, but we cannot see them.

The arrangement of electrons in an atom determines the sizes of the quantum jumps, and thus the energy and

colors emitted, known as emission spectrum. In this way, the emission spectrum serves as a ‘fingerprint’ of

the element to which the atoms belong. We can view the emission spectrum of colors all at once with the naked

eye. It will appear to be one color. It is also possible to view the separate colors of the emission spectrum by

using a spectroscope, which bends light of varying energies differently. Low-energy red light is bent the most

and high-energy violet, the least. This allows us to see the various distinct colors of the emission spectrum of a

sample.

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Electron heated to an

excited state.

Electron falls back to ground state

and emits a photon of light

spectroscopes

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Wood Splints

In this lab, you will record the flame test color of several metals by wetting a wood splint in a salt solution, then

placing the splint into a bunsen burner flame. Use ONE wood splint per salt solution. Discard the splint into

the waste beaker after you have tested the solution and DO NOT burn your fingers, hair, clothing or each

other!!!

Spectroscopes

Use spectroscopes to view the spectrum of white light from the window, then view the spectrum in the separate

colors of the emission spectra. This may be difficult to do under our lab conditions, because the flame test is

quick and the lab lights will be dimmed to better see the flames.

Cobalt Blue Glass Filters

Cobalt blue glass filters are often used when viewing mixtures of metals to screen out light that is yellow. The

human eye sees yellow very well, since it is in the middle of the visible spectrum. Colors at the edges of the

visible spectrum, especially violet, are more difficult to see. Cobalt glass absorbs light in the yellow

wavelengths, but is transparent to light of higher energy (this is why it looks blue!). Viewing a yellow flame

through cobalt glass will allow us to see if there is any higher energy light present.

Unknown substance

You will use the data we collect to identify a metal in an unknown salt solution. This process is the same as

that used by chemical laboratories to identify the make-up of chemical contamination in chemical spills, land

fills, industrial sites, etc. This must be done to determine the possible threat to human health and the ecosystem

due to contamination.

Wood splint


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Objective:

To observe the relationship between various elements and emission spectroscopy and to identify an unknown

substance.

Pre-Lab Questions:

1. Explain how the electrons play a role in the color of light that we see in the flame test.

2. Why is the color of each metal different?

3. Since you will be recording the color of light that you see, will you be recording quantitative data or qualitative data?

4. Explain why a process, such as the Flame Test, would be important in

a) Forensics:

b) Astronomy:

c) Environmental and Industry Issues:

Materials: Safety glasses

Wood splints

Bunsen burner

Test tube with each salt solution

Test tube rack

Waste Beaker

Tweezers

Spectroscope

Cobalt blue glass Suggested compounds: Barium chloride, Potassium chloride, Calcium chloride, Copper (II) nitrate, Strontium nitrate, Lithium chloride

Safety: 1. Safety goggles must be worn at all times

2. Many of these salts are toxic. If you come into contact with any of the compounds, wash the contacted area thoroughly.

Procedure: 1. To perform a flame test, use the tweezers to obtain one wood splint from the test tube which has been soaking in

salt solution.

2. While holding the wood splint with the tweezers, place the solution-soaked splint horizontally in the hottest part

of the flame. Make careful observations of the flame and record your observations in your data table.

3. Use the spectroscope to observe the emission spectrum for each compound and record the wavelengths.

4. Test each of the remaining compounds.

Red = 656 nm

Yellow = 587 nm

Green = 486 nm

Blue = 434 nm

Violet = 410 nm

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Directions: Complete the data table with the missing information.

Test

Record the Compound

Flame Color

to the

Naked Eye

Flame color through the

Spectroscope

Flame color

through the Blue Glass

Filter

Wavelength

(nm)

Test #1 Test #2 Test #3 Test #4 Test #5 Test #6 Test #7 Test #8 Test #9

Unknown

Compound Unknown Compound:


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Clean Up:

1. Clean up all materials—make sure all wood splints are neatly placed in the waste beaker.

2. Be sure your current lab station looks like it did when you walked in.

3. Wash your hands thoroughly before leaving the laboratory.

Discussion and Analysis:

1. How does the flame test provide support for quantized energy levels? Explain.

2. The unknown compound was the same as one of the other compounds. Which one was it? HOW do

you know?

Conclusion: Answer in complete sentences. Write a short paragraph about what you have learned (not if you liked the lab or not) regarding what

information flame tests provide about atomic structure. What were some sources of error in the lab (at least 2)?

How would these errors have affected your results? What would you do differently if you could do this lab

again? Why?

After completing the Flame Test Lab, I have learned…


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Case Study: Identification of Elements that Affect Human Health Although the flame test was useful for our purposes, researchers such as clinical chemists, forensic chemists, and environmental

chemists use various other methods to detect elements and compounds in bodily fluids (i.e. urine, blood, tissue samples). For instance,

when testing professional athletes, chemists will use gas chromatography-mass spectrometry to determine if an athlete is “doping” in

order to improve performance. Chromatography separates atoms and molecules by size and mass spectrometry measures each

particle’s mass to determine their identity. It was through this method that Fallbrook, CA, Floyd Landis was accused of doping during

his one-time Tour de France victory and was forced to return his winnings. Marion Jones was also accused and convicted of doping

and had to return 5 Olympic medals from her turn in the 2000 Olympic Games in Sydney, Australia. Forensic chemists and

environmental chemists also utilize various types of chromatography (i.e. gas, thin-layer, and paper) to separate chemicals by size as

well as microscopy, X-ray, infrared and ultraviolet. The clinical chemist in this case study used EDXA (Energy dispersive X-ray

analysis) to determine the cause of his patient’s illness.

Antonio Pedro University Hospital, Rio de Janeiro, Brazil A 36-year-old man, with medical record number #1827904-1, presented

to Antonio Pedro University Hospital in Rio de Janeiro, Brazil, with

pulmonary infiltrates (foreign substances) in both lungs detected on a

chest scan. He complained of shortness of breath (SOB) during activity.

The patient has been working in the ship industry for 7 years, making

coating materials, while never wearing respiratory protection. His past

medical history was unremarkable, he has no allegies and he has never

smoked.

Upon admission to the hospital, the patient was completely coherent and

functional. His blood (hematology), liver panel (hepatic), and kidney

function (renal) were all within the normal range. Sputum (mucous)

analysis for acid-fast prokaryotes and neoplasia, both indicators for disease, were negative. Pulmonary breathing

functions seemed relatively normal.

Since the lung scan showed foreign materials in both lungs of the patient, a lung biopsy was performed. An abnormally

high macrophage count was discovered and numerous granulomas which are cells that clump together when fighting

particles that are foreign to the body were observed.

Fill in the patient information sheet below. Patient Triage and Medical History

MR# Age: Gender

Male Female

Allergies: Occupation:

Medical history:

Presenting symptoms upon admission:

Laboratory results:

Hematology Hepatic Analysis Renal Analysis

□CBC □ Liver Panel □ BUN

□Differential □ Creatinine

Respiratory Indicators

□Sputum □Neoplasia □SOB (shortness of breath)


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Macrophage mass

and oversized cell Nodules present in lung scan.

( Round, abnormal spheres.)

Can you identify the

large cell with many

nuclei?

Large cell with

many nuclei

Large abnormal cell magnified

Identify the cytoplasm and circle

each nucleus.

Macrophage cell with platelike

foreign substances

Figure 1


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The patient was asked to bring in a sample of the coating materials and resin that he used for work on a weekly

basis. A clinical chemist performed an EDXA spectrum on the samples and the results are shown below.

Analysis: Identify the elements found the shipping industry materials in spectra A, B, and E.

Question Answer 1) Which elements found in the alveolus biopsy in

spectrum C are also found in the industrial materials

(A, B and E)?

2) Which elements found in the alveolus biopsy in

spectrum D are also found in the industrial materials

(A, B and E)?

3) Which elements are missing from the biopsy?

4) How can you account for the elements that are

present in the industrial materials but are not found in

the macrophages?

5) How would you diagnose this patient and what

advice would you give to him?

Figure 2: EDXA spectra of coating material fibers. A) Fiber spectra B) Resin spectra C) Spectrum of

platelike material found in patient’s macrophages from the alveoli D) Spectrum of different platelike material

found in patient’s macrophages from the alveoli E) Talc spectrum

Documents

Flame Test Lab The Identification of an Element · 1. To perform a flame test, use the tweezers to obtain one wood splint from the test tube which has been soaking in salt solution