Activity 4 1/13/11 Gas Observations

Why did balloons get bigger when the pump was turned on? What was happening at the molecular level?      

I believe the balloons got bigger because the pump was taking molecules out of the container.  The CO₂ molecules in the balloons were becoming enlarged as the air molecules in the container were being sucked out of the container, making the balloons expand. The molecular level is rising inside the balloons, making the molecules move and expand throughout the balloons.