Physical Science & Chemistry Projects

Question: How Much Oxygen is in Our Air?

The air around you is made up of about 21 percent oxygen. This science experiment will show you how to discover the amount of oxygen for yourself by analyzing a chemical reaction between oxygen and rust. 

Materials Needed:

(Any of The Materials Highlighted in Blue are Clickable Links for Purchasing)

Package of fine steel wool (available at hardware stores)

Wide, shallow bowl or dish

Water

Food Coloring

Rubber Gloves

Glass jar

White vinegar

Four test tubes

Permanent marker

Procedure:

1. Fill the glass jar with equal parts Vinegar and Water
2. Put the package of steel wool in the glass jar, and leave it there overnight to soak. This will form iron oxide (rust) on the steel wool.
3. Pour an inch of water into the shallow bowl/dish. Add two drops of food coloring to the water.
4. Wearing gloves, pull a few strands of the steel wool from the rusted piece, and roll them together to make a tiny ball. Repeat this procedure two more times so you have three tiny balls. The balls should be slightly wider than the test tubes.
5. Use a pencil to push one ball all the way to the bottom of one of the test tubes, one ball three quarters of the way to the bottom of a second test tube, and one ball halfway to the bottom of a third test tube.
6. Make a paper ball the same size as the balls of steel wool, and push it to the bottom of a fourth tube.
7. Put the four tubes upside down in a row in the shallow dish of prepared water. Leave the tubes there for 24 hours.
8. Now mark the water level on each tube. Notice the difference in water level. The tube with the paper in it should not have risen. Now measure the length of each tube, pretend that the bottom of the steel ball is the highest point of the tube. Write both of these measurements into a table, like the one below.
9. Fill in the fourth column of the table by dividing the amount the water moved up by the length of the test tube. Remember that the water that rose into the test tube was actually replacing the oxygen that reacted with the rusty steel wool. The percentage for all three tubes should be the same, since it is the same as the amount of oxygen in the air, 21% give or take.

Question: How Do Acids and Bases Affect Enzymes?

Summary: Enzymes are proteins that accelerate chemical reactions. They occur in the body in our digestive system, for example, to speed up the process of breaking down food into molecules that provide nutrients to the body. They are also using in many manufactured products, including cleaning products, cheese, beer, and biofuels. This experiment tests the effect of different levels of acids and bases on a common enzyme—yeast.

Materials Needed:

(Any of The Materials Highlighted in Blue are Clickable Links for Purchasing)

5, 70 mL Glass Test Tubes   

Plastic Test Tube Rack  

Masking Tape

Permanent Marker Pen

5 plastic drink stirrers

1 small glass

Distilled Water (1/2 Cup)

Active Dry Yeast

Baking Soda

Set of measuring teaspoons

Hydrogen Peroxide

Lemon Juice

Baking Soda

Ruler

Measuring Cup

pH test strips                    

Pen and Paper for Taking Notes

Project Procedure:

1. Label the test tubes as follows: #1-Control, #2-Low Acid, #3-High Acid, #4-Low Base, #5-High Base using the masking tape and permanent marker and place each test tube in the stand.
2. Place one of the drink stirrers in each of the test tubes. Do not move them from one test tube to another.
3. To the test tube marked #1-Control, add 2 teaspoons of distilled water, 1/8 cup (1 oz.) of hydrogen peroxide and 1/8 teaspoon yeast. Use the ruler to measure the highest point that bubbles reach and record that on your note paper.
4. To the test tube marked #2-Low Acid, add one teaspoon of distilled water, one teaspoon lemon juice, 1/8 cup hydrogen peroxide, and 1/8 teaspoon yeast. Stir. Use the ruler to measure the highest point that bubbles reach and record that on your note paper.
5. To the test tube marked #3-High Acid, add two teaspoons of lemon juice, 1/8 cup of hydrogen peroxide and 1/8 teaspoon yeast. Stir. Use the ruler to measure the highest point that bubbles reach and record that on your note paper.
6. Pour ½ C of distilled water into the small glass. Add 1 teaspoon of baking soda, stirring to dissolve.
7. To the test tube marked #4-Low Base, add one teaspoon of the baking soda solution you created. one teaspoon of distilled water, 1/8 cup of hydrogen peroxide, and 1/8 teaspoon of yeast. Stir. Use the ruler to measure the highest point that bubbles reach and record that on your note paper.
8. To the test tube marked #5-High Base, add two teaspoons of the baking soda solution, 1/8 cup of hydrogen peroxide, and 1/8 teaspoon of yeast. Stir. Use the ruler to measure the highest point that bubbles reach and record that on your note paper.
9. Use the pH test strips to measure the pH of each test tube Record this information and and use it, along with the measurements of the height of the bubbles, to hypothesize about how acids and bases affect enzyme activity.