2 class periods of 45 minutes each
Small Groups
A fun and engaging lesson where students learn about physical and chemical changes by using pennies and various substances. Students will get to see exciting changes before their eyes and also by waiting until the next day. Properties of chemical changes such as color, gas and reactions of substances will be learned.
WARNING: Do not let students handle the toilet bowl cleaner!
Students should know the basic differences between chemical and physical changes and that chemical changes are not reversible. (For elementary school purposes). Students should understand how to find the year on a penny or coin.
1. Use Science Process and Thinking Skills
Students will run the experiment on two separate days.
Part 1:
Have students gather a paper towel, plate, 1 penny, and vinegar.
Folding the paper towel so it is thick and placing it on a plate with the penny, have students record any observations they like about the current penny situation. They should also hypothesize about what could happen to their penny. (such as "nothing" or "it might explode!") Students then can pour a small amount of vinegar onto the penny and use the masking tape and markers to label this part of their experiment (Part 1). Students can then record new observations and what type of change has occurred.
Part 2:
Students gather penny, 1 teaspoon of salt, small cup, 1 teaspoon of vinegar, paper towel.
Students should put some salt into the cup and put a penny in it and record any observations. Adding the vinegar, then record more observations. Remove the penny to another paper towel and also label it. (Part 2).
Part 3:
Materials:
Place a paper clip into the Salt and Vinegar solution.
Put your name on the cup of your group
Let your paper clip and salt and vinegar sit overnight. Students should record their observation of the paper clip the next day and note what happened and what kind of change it was. Have students handle the paper clip and see if the coating stays on or off.
Part 4:
Materials:
Students will understand they need to measure properly! They will have to put a trash bag over a table so it doesn't get damaged. Students should Find two glass beakers. Fill one with 35 ml of vinegar and label it (vinegar) Fill one with 35 ml of toilet bowl cleaner and label it (cleaner) Scrape two (1983 or newer) so you expose the zinc inside. Scrape either with sand paper or use a metal file. The students like using the sand paper so they can do it themselves. Place one penny in the vinegar and one penny in the cleaner. Have students record what happens right away and what happens the next day, noting what kind of changes occurred.
Students can identify additional changes, such as the type of change that occurs when sandpapering the pennies.
Students can also use different types of substances to clean the pennies and observe changes and be creative about it, such as apple juice or ketchup (things you might find at school).
Students could also try the experiment using different coins such as a nickel to see if there is a difference or a quarter. Suggest trying that in advance with a teacher if using the HCL or toilet bowl cleaner.
Students could draw pictures of what happened or write a story about what use chemical changes might be.
There are two worksheets attached which can be used to go over together or individually and then together to review changes and apply what they saw in the experiment to real questions.