MHS Chemistry

Name: _________________

2.A.x Physical & Chemical Changes of Cu
Section A B C D E F G

 

Due Date: __________

In this activity you will be investigating some physical and chemical changes involving copper and zinc from US Pennies.  Be sure to record your observations on this sheet as well as in your bound lab notebooks.   This lab involves the use of very high temperatures and concentrated nitric acid.  Poisonous gases will be produced.  Wearing goggles and using the hood is absolutely mandatory.  You will be asked to sit down the first time I see you without goggles on, and will not be allowed to participate. Put on your goggles and don’t take them off until the end of the period.

Part 1  Physical Changes

  1. Obtain one “new” penny and one “old” one.  The dividing line is 1982.  The outside of the pennies are all copper.  Record your observations of the appearance of copper.
  2. Fill a medium beaker with water.  Set up a Bunsen burner according to your teacher’s directions, so the flame is over the water.
  3. Use metal tongs to hold the new penny in the flame.  Record your observations.
  4. Use metal tongs to hold the old penny in the flame.  Record your observations.

Part 2  Chemical Changes

  1. Bring your pennies to the hood.  Place the old penny in a small beaker, and add a few drops of concentrated nitric acid.  Observe the changes.  The reaction you observed is:                                      

    Cu(s) + HNO3(l) ® Cu(NO3)2(aq) + H2O(l) + N2O4(g)        followed by    

    N2O4(g) ® 2NO2(g)  

  2. Repeat the previous step with your new penny.  What differences did you observe?


Part 3  Clean Up

  1. The pennies + acid should be rinsed into the Funnel Of Doom.
  2. Leave your lab table clean and ready for the next class.
  3. Fill in the observations on the back of this sheet.
  4. Take off your goggles and sit down.

   

OBSERVATIONS

 

Part 1  Physical Changes

  New Penny:    

 

 

 

Old Penny:

 

 

 

New Penny in flame:

 

 

 

Old Penny in flame:

 

 

 

 

Part 2  Chemical Changes

  1.   Old Penny + Nitric acid (reaction):

 

 

 

            Cu(NO3)2(aq) (appearance):

 

 

 

            N2O4(g) (appearance):

 

 

 

            NO2(g) (appearance):

 

 

  2.   New Penny + Nitric acid (differences from old penny reaction):

 

 

 

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