Penny Wars

Acids react with metals as soon as they come in contact, however, sometimes the results can be difficult to observe at first.  We will perform the following procedure, making and recording observations.  Because the effect may be difficult to see for a few days, we will preserve the reactions for next class period and make final observations. 

1. Obtain two beakers. Label one water and one vinegar.
2. Put a penny (minted before 1983, as the chemical composition is different) in each beaker.
3. Add only enough water or vinegar to the corresponding beakers to barely cover the pennies. 
4. Use pH paper to test the solutions.  Dip a paper into each solution for about 2 seconds.  Compare them with the color chart.
5. If the pH of the water is below 6, add a very small amount (a pinch) of baking soda to the beaker.  Recheck the pH and repeat until the pH reads between 6 and 7.
6. Seal the top of each beaker to prevent evaporation.
7. Place beakers in a safe, dry area until next class period.
8. During the next class period we will check the beakers and observe any changes that have occurred.
9. Remove the pennies from the beakers and wash them with water.

Observations:

Conclusions and Discussion:

What changes occurred during the time period?

What can you conclude about the effects of acid rain?

Lesson 3

Acids and Bases Unit