<p> Ideal Gas Lab “Big Lungs”</p><p>Purpose: In this lab we will measure the change in volume of a balloon after one breath is exhaled into it. When we inhale, we expand the volume of our lungs. Because of this the pressure of the air in our lungs is lowered. This pressure difference causes air molecules to enter our lungs through our mouths until the external pressure is equal to the pressure in our lungs. When we exhale, we contract the volume of our lungs which increases the pressure in our lungs. Air molecules leave our lungs until the pressures equilibrate. Since the external temperature and pressure will remain constant during the lab, we will be able to calculate the number of moles of air added to the balloon using the ideal gas law. </p><p>Materials:</p><p>Balloon Measuring Tape</p><p>Procedure: 1. Blow your balloon up a little until it’s somewhat spherical. 2. Use your tape measure to measure the circumference of the balloon. 3. Exhale one breath into the balloon. Try to exhale as much as you can. 4. Measure the new circumference of your balloon. 5. Calculate the radii of your balloon before and after. 6. Use these radii to calculate the two volumes of your balloon. 7. Use these volumes with the ideal gas law to calculate the number of moles added. 8. Multiply your moles added by Avogadro’s number.</p><p>Calculations:</p><p>Circumference of a circle = 2πr Volume of a sphere = 4/3πr3 </p><p>Circumference 1 = ______Radius 1 =______Volume 1 = ______Circumference 2 = ______Radius 2 =______Volume 2 = ______</p><p>Use the ideal gas law to calculate the number of moles below: (Assume STP)</p><p>Number of molecules = ______</p>