Climbers at high altitudes are at risk because of the low concentrations of oxygen.
The oxygen concentration where you live is probably much higher. What is the concentration of
oxygen in the air where you live? Do this activity and find out.
Before you begin, predict what percentage of the air you breathe is oxygen.
_____%
Explain your prediction on a separate sheet of paper.
Place a vertical strip of masking tape along the side of each test tube.
Use a pencil to make a mark 1 cm (.40 in.) below the rim of each test tube.
Wet a small piece of steel wool, about the size of a quarter. Press the steel
wool into the bottom of one of the test tubes. Use a pencil to wedge it in
tightly.
Fill each beaker almost full with water. Turn the test tube with the steel
wool upside down and attach it to a burette clamp. Lower the test tube into the
water until the water rises to the 1 cm (about .40 in.) mark. Repeat with the
second test tube and beaker. Let the test tubes stand for a day or two.
Each day mark the water level in both test tubes. Be careful not to move
the test tubes as you mark them. Also describe the amount of rust on the steel
wool. When the water stops rising, mark the final height of the water on each
test tube. Compare the water level in both test tubes.
