Conservation of Mass Lab! Practice!

Introduction! Is mass conserved in other chemical reactions as well? The answer to this question may not be immediately obvious. After all, everyday experience may suggest that mass does change during a chemical reaction. For example, a campfire burns down to a pile of fluffy ashes that have much less mass than the original wood. One of the first scientists to study this question was the eighteenth-century French chemist Antoine Lavoisier. Until this time, chemists had not considered the possibility that some reactions could involve gases. Gases, like other forms of matter, have mass. In his experiments, Lavoisier used equipment designed to trap all the reactants and products, including any gases produced during the reactions. Lavoisier found that mass was always conserved if all the reactants and products were considered. Lavoisier’s conclusion has been supported by the work of many other scientists and is now considered to be a scientific law. It is known as the law of conservation of mass: In any given chemical reaction, the total mass of the reactants equals the total mass of the products. The law of conservation of mass makes sense when you consider what is occurring at the atomic level. Experiments have shown that, during a chemical reaction, the atoms in reactant molecules are rearranged to form products. Therefore, all the atoms that existed in the reactants are still present in the products of the reaction. Atoms cannot be created or destroyed. That explains why the total mass of reactants is equal to the total mass of products. Procedure Part A: Baking soda (NaHCO3) and vinegar (C2H4O2) in a closed Ziploc bag 1. Safety glasses were put on 2. Ziploc bags were labelled “Ziploc bag 1” and “Ziploc bag 2” 3. 10ml of baking soda was measured into a small beaker. 4. The measured 10ml of baking soda was poured into Ziploc Bag 1. 5. 15ml of vinegar was measured into a graduated cylinder. 6. The measured 15ml of vinegar was poured into a clean beaker. 7. The beaker of 15ml of vinegar was cautiously and carefully placed into Ziploc Bag 1 and then sealed. It was made sure that the beaker’s contents did not spill. 8. The bag was placed on the balance and then the total mass of the bag, container and its contents, were measured and recorded. 9. The vinegar and baking soda were gently mixed together by knocking over the beaker and letting the vinegar spill into the baking soda. The bag was not opened. 10. Ziploc bag 1 was set aside until there were no bubbles, signaling that the chemical reaction was finished. 11. The total mass of bag 1 and its contents were measured and recorded. It was made sure that the bag remained sealed the entire time. Write a hypothesis in "If...then...because" format Make sure that your hypothesis is about the mass at the beginning of the experiment vs the end! Data Table Materials Mass Before Reaction Mass after reaction Ziplock Bag N Vinegar N Beaker N Baking Soda N Total Did your data support your hypothesis why or why not? Was the mass the same before and after the reaction? If not why do you think that could be? How do you know a chemical reaction occurred? What do you think would happen if we didn't put the beaker in a bag? How would this effect the final mass? Explain your reasoning