Law of Conservation of Mass / Introduction
to Weighing Using the Analytical Balances
Lab Partners: Matt Hattenburg & Peyton Dannewitz
Date: March 18, 2015
The Law of Conservation of Mass states the matter can neither be created nor destroyed. Antoine Lavoisier is credited with the discovery of the Law of Conservation. Lavoisier carried out his ideas as early as 1774. The Law of Conservation has been proven by a variety of experiments. For example, if you were to light a candle in completely closed room the mass of the room before lighting the candle would be exactly the same as the mass after lighting the candle. By combining vinegar and baking soda in a sealed water bottle we were able to further support the Law of Conservation of Mass.
The purpose of this experiment was to create a chemical reaction inside of a closed system in order to observe the Law of Conservation of Mass. A secondary objective of this lab was to use the analytical effectively and precisely.
If we mix baking soda and vinegar in a closed system then the mass of the reactants will equal that of the products because the Law of Conservation of Mass states that matter can neither be created nor destroyed.
• Water Bottle
• Water Bottle Cap
• Baking Soda
• Graduated Cylinder
• Analytical Balance
• Weighing Paper
• 12 mL Plastic Test Tube
It was necessary for us to follow the directions carefully and precisely in order to obtain the desired results. We began by zeroing the analytical balance. Next, we made sure that we had all the required materials to perform the experiment. Then, one member of our group folded the weighing paper in half and placed it on the analytical balance. We then proceeded to zero the analytical balance with the lid closed and the weighing paper on the balance. Next, we weighed out 2.0 grams of baking soda and put it inside the empty water bottle. Next, we carefully poured 5 milliliters of vinegar into the 12 milliliter plastic test tube. The next step was executed by gently tipping the water bottle, then slowly placing the 12 mL plastic test tube and its contents inside the water bottle without letting the vinegar escape. Having made sure no vinegar had found its way out of the test tube, we put the cap on the water bottle tightly. Then, we had one partner hold the water bottle while another partner wrapped the parafilm tightly around the cap. Parafilm was used to ensure that little to no air could escape the bottle, guaranteeing the most accurate results possible with the given materials. Before weighing the bottle and its contents, it
was important to zero the analytical balance. Then, we recorded the weight before the reaction. We had then tipped the bottle, allowing the vinegar to mix with the baking soda creating a
chemical reaction. Our group observed fizzing within the bottle. After the reaction had settled, we weighed the bottle and everything inside of it. Having recorded the weight before and after the reaction, our group was able to observe that the weight had not changed following the reaction. Finally, we took the cap off the bottle letting all of the gas escape and weighed the bottle with the cap back on. A change in weight had been recorded after removing the cap and letting the air out.
Table used to record the mass of the bottle during the experiment.
Mass of Bottle Before Reaction
Mass of Bottle After Reaction
Difference in Mass (Before minus
Mass of Bottle After Reaction
Difference in Mass (Unopened ...
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