Lab Report



Dry Experiment: Observing the change in volume of air as it is exposed to up to seven atmospheres of pressure

Underwater Experiment: Observing the change in volume of air as it is exposed to a depth of sixteen feet of pressure, descending in increments of two feet

Problem Statements:

Dry Experiment Problem Statement:
What will happen to the volume of the graduated cylinder when up to seven atmospheres of pressure are added onto the cylinder with a bike pump?


Underwater Experiment Problem Statement:
What will happen to the length of the air bubble inside of the tube as it is taken down to sixteen feet deep in a pool in two feet increments?


Method and Materials:

Underwater Experiment:
-hard plastic clear tubing with one end plugged.
-Permanent Marker
-Clip Board
-China Pen
-Scuba Gear

-turn tube over so that plugged end is facing sky.
-lower the tube two feet at a time
-record length of bubble in two feet depth increments until reaching sixteen feet

Dry Experiment:
-Plastic soda bottle
-graduated cylinder
-heavy bolt that will fit through the bottle
-rubber band
-bike pump w/ pressure gage
-bottle cap with bike needle going through it
-rubber cement
-curved narrow glass tube

First, the graduated cylinder needs to be connected with the bolt. Cut about four inches of string in half, and put both strings on opposite sides connecting the bolt and the open end of the cylinder so that there is about two inches in between the bolt and the cylinder. Now, fill the soda bottle with water. Lower the cylinder and bolt into the bottle, so that the bolt is resting on the bottom of the bottle, and the cylinder is upside down with no water in it, but only trapping air. Since the air is filling up the whole cylinder, beyond the twenty-five milliliters that the cylinder is designed to measure, some air needs to be taken out of the cylinder so that there is only twenty-five milliliters. Take the glass narrow tube and put the curved end into the bottle, and lower it to the bottom. Now maneuver it so that the curved end of the class tube goes up into the graduated cylinder. Suck out air manually until inside graduated cylinder, there is only twenty-five milliliters of air. Now seal the bottle with the cap that has the needle going inside of the bottle now. Attach the bike pump to the needle. Now it's time to start the experiment. Push down on pump until you have added one more atmosphere of pressure onto the cylinder. Record the volume of the bubble. Keep on adding atmospheres of pressure with the pump and record the volume of the bubble until you have added seven atmospheres of pressure.

CLICK to see set up diagram



Analytic Essay


These experiments gave us the approximate results that we were looking for. As there is two atmospheres of pressure on a certain volume of air, the volume of air is one half of the amount that it was at when there was one atmosphere of pressure on the air. When there are three atmospheres of pressure, the volume of the air is one third of the original volume. Four atmospheres, one fourth, and so on. When we went down in increments of two feet, the amount of change of the volume of air decreased by less and less as we went down to sixteen feet deep.


Back To Top