Lab Experiment

The purpose of this lab was to determine if a there is a change in mass when a gas is produced and determine if gas has mass. To conduct this experiment, the group must be careful not to let the Alka-Seltzer tablet get wet before the bottle is closed by wiping the lip of the bottle and the cap so it remains dry, or risk gas escaping into the air and not being captured by the bottle. Also, the group must be sure to close the bottle tightly with the cap, because gas may escape this way as well. During this investigation, it was determined that there is 0 change in mass when a gas is produced, because the mass of the bottle, water, Alka-Seltzer tablet, and cap remained the same even after the Alka-Seltzer had a chemical reaction with the water and
changed into a gas. This is considered a chemical change because the production of gas is one of the indicators of a chemical change. The bottle and cap in this experiment was important because the objects contained the substances and kept the materials in a closed system. However, when the closed system is opened to the outside world, the gas produced from the Alka-Seltzer’s reaction with the water was released, which showed a change in the mass of the bottle, water, cap, and tablet. This part of the experiment determined that gas does have mass, because the mass of all the objects that were measured in this experiment decreased after the gas was released. When comparing with class data, the majority of the class got the result of having no change in mass when a gas is produced.
While some groups got different results, most were within the range of the sensitivity of the balance. With the exception of one outlier, the overall trend of the class was that there is 0 change in mass when a gas is produced. This suggests that there is no change in mass when a gas a produced in a closed system, which supports the Law of Conservation of Mass. This law states that the mass remains the same throughout all changes provided it is in a closed system. Although the class did not compare the data from when the gas was released, looking at the group’s data which shows a decrease after the gas is released, the group can conclude that gas has mass. A possible error that may have been encountered is that the group accidentally got the Alka-Seltzer tablet wet before closing the bottle, causing the gas that would be produced to escape into the outside air. This error would have caused the group to have an apparent decrease in mass because the gas escaped. Another possible error is that the group did not screw the lid on tightly enough to the bottle, allowing the gas to escape through the
gaps. This error would have caused an apparent decrease in mass as well from the lost gas’s mass. In conclusion, there is no change in mass when a gas is produced and gas does have a mass.