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Flame Tests of Metal Ions

Chemistry Laboratory

 

Purpose:To discover the different frequencies of light that is emitted by various metallic ions.

 

Safety:

     Follow appropriate safety procedures when operating the burners.Tie back long hair and secure loose clothing.

     Many of the salts used in this experiment are toxic.Be sure to wash hands thoroughly after coming into contact with any of the substances.

 

Procedure:

1.  You will be rotating through 8 different stations in a clockwise direction.You will have no more than 5 minutes at each station.

2.  If the burner is not lit, follow the appropriate procedures for lighting the burner.Pick up a correctly labeled nichrome wire loop or paperclip loop.

3.  Dip the wire loop into the beaker of distilled water.Then dip the wire loop into the beaker of metal salt crystals so that a FEW crystals adhere to the loop.Donít pick up too many crystals or the will make a mess!Remember, some of these are toxic and we do not want crystals lying around the station to get onto your skin or into your eyes.

4.  Place the wire loop into the burner flame.Observe the color produced and record it in a table you construct.Watch carefully because some colors will not last long.Be as descriptive as possible. (e.g. red orange instead of orange)

5.  Rotate to the next station.DO NOT LEAVE THE FLAME UNATTENDED.If another group is ready to use your station, you may leave the flame in their care.Otherwise, extinguish the flame by turning off the gas before leaving your station.

6.  Repeat steps 1-5 until you have observed all seven metal salts and the unknown.

 

Observations:

Record you observations as directed in the procedure.Use a ruler to make your observation table.†† You are using the following salts:

     Lithium Chloride, LiCl

     Sodium Nitrate, NaNO3

     Calcium Nitrate, Ca(NO3)2

     Strontium Chloride, SrCl2

     Copper II Nitrate, Cu(NO3)2

     Magnesium Chloride, MgCl2

     Iron II Nitrate, Fe(NO3)2

     unknown

Conclusions:

     What is the unknown metal ion?Describe what evidence you have to support your answer.

     Explain how colors are produced by the metal ions.Include terms such as ground state, excited state and photon in your explanation.

     Explain how a forensic scientist could use similar methods to determine an unknown substance at a crime scene.

     List the electron configurations for the metal ions used in the compounds you tests.You may use the noble gas configurations if you would like.

     Draw the orbital box diagram for each.

     Unknown is a mixture of three different salts, test to make sure all colors are visible.†††††††††††††††††††††††††

 

Flame Test Lab Rubric

 

 

Professional demeanor

Needed to be reminded of lab behavior once.

Had to remind about lab practices/ safety more than once.

Behavior

10 points

5 points

0 points

 

Followed procedure without asking questions that was on the procedure.

Needed to be reminded to read the procedure once.

Needed to be reminded to read the procedure more than once.

Procedure

20 points

5 points

0 points

 

Data recorded neatly and accurately.

Data was there, but messy Ė would be hard to reconstruct.

Data haphazard or copied data from another group.

Data Recording

10 points

5 points

0 points

 

 

 

 

Safety

No safety issues

One minor safety infraction

Two or more safety infractions

 

30 points

20 points

0 points

 

All equipment/safety clothing stored properly, lab station clean and neat

Safety equipment not neatly stored, had to be reminded to wipe down station.

Unsatisfactory cleanup

Cleanup

10 points

5 points

0 points

 

All question answered satisfactorily.

One incorrect answer or minor issues on accuracy.

Gross conceptual errors

Analysis

20 points

10 points

0 points

 

 

Grade:_______________

 

 

 

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