NAME:________________________DATE:_____________PERIOD:________
Emission Spectra Lab Part 2
Each group will be called to the front of the room to observe the activity. Use
Part One of this lab to answer the questions until your group is called.
REVIEW:
1.
What is an excited electron?
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2. How much energy is released when an electron decays?
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3. Why do elements give off different colors of light when they are burned?
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4. How would you determine the composition of an unknown substance with a
spectrometer?
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5. List five safety rules you should follow when you are in the vicinity of a lit
Bunsen burner.
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6. Read all the procedures thoroughly NOW so you are prepared. Then, name
three accidents that could potentially happen if you do not follow safety
rules.
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MATERIALS:
Safety equipment:
Safety goggles
Fire Blanket
Fire Extinguisher
Spectroscope
Bunsen burner
Dropper assemblies
Copper Sulfate
2
Sodium Carbonate
Lithium Chloride
2 unknown solutions
PROCEDURES:
1. Put on your safety goggles when you are called to the front of the room. So,
when you arrive, safety goggles should be on. Tie back long hair and loose
clothing. Never touch the flame of the Bunsen burner. Never lean over the
Bunsen burner.
2. Choose one person in your group who has excellent spectroscope skills. One
person will view the flame through the spectroscope and determine the
location of the emission lines.
3. Your teacher will light the Bunsen burner. Each dropper assembly contains
some drops of a chemical solution with a wire loop protruding through the
dropper. The wet loop will be held at a 45 degree angle to the flame. Note
the color of the flame of five different solutions in the data table.
4. One person in the group will view the flame with a spectroscope. DO NOT
BRING THE END OF THE SPECTROSCOPE TOO CLOSE TO THE FLAME.
IT WILL MELT. That person will draw the emission lines in the data table
and share the results with the group when they return to the table.
5. When you return to your table, put your safety goggles in the bucket of
warm soapy water. Then dry them with paper towels and leave them in the
bucket on the lab bench.
6. Answer the questions.
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DATA TABLE:
Name of Compound
Flame Color
Copper Sulfate
Lithium Chloride
Sodium Carbonate
Unknown #1
Unknown #2
Emission Spectrum – Copper Sulfate
4
5
6
7
6
7
6
7
Emission Spectrum – Lithium Chloride
4
5
Emission Spectrum – Sodium Carbonate
4
5
4
Emission Spectrum – Unknown #1
4
5
6
7
6
7
Emission Spectrum – Unknown #2
4
5
Questions:
1.
Compare the emission spectra and flame colors of the known and unknown
substances. Is unknown #1 copper chloride, sodium chloride or lithium iodide?
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Why?________________________________________________________
2. Compare the emission spectra and flame colors of the known and unknown
substances. Is unknown #2 copper chloride, sodium chloride or lithium iodide?
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Why?_________________________________________________________
3.
What do you expect the emission spectrum of lithium iodide to look like? Why?
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