Sophie Norton Burning Magnesium Lab
th is experiment to determine whether burning magnesium in a Purpose: We are conducting this crucible will yield a mass that is greater, less, less, or the same by applying our knowledge of balancing chemical reactions and sto ichiometry. ichiometry. Hypothesis : If we react .12 grams grams of magnesium with oxygen in a crucible, crucible, then at the end of
the experiment, the mass of the magnesium oxide will be greater than the mass of the magnesiumbecause in order for magnesium to form, magnesium oxide oxygen must be added, therefore the mass increases. Theoretical Background: In order to use the data we collected in this experiment, we must have
a basic understanding of balancing chemical equations and stoichiometry. Chemical equations must be balanced because the law of conservation of o f mass states that matter is neither lost nor gained in a chemical reaction. To balance a chemical equation, you have to make sure the number of atoms of each element e lement present isthe sameas reactants and products.To pro ducts.To find the weight of the amount of magnesium oxide created by a reaction between oxygen and magnesium, we must use stoichiometry. Stoichiometry is used to find the relationships between react ants and products of a chemical reactant by calculating the number of moles, masses, masses, atoms,and molecules. In this particular experiment we had to know how to calculate the mass of the reactant magnesium to the mass of o f the product magnesium oxide. In order or der to do this, we had to use stoichiometry to convert grams of magnesium to moles of magnesium to moles of magnesium oxide to grams gr ams of magnesium oxide. Materials and Equipment : y y y y y y y
(1) Ring Stand (1) Crucible (1) .12g of Magnesium (1) Bunsen Burner (1) Pair of Tongs (1) Rubber Wire (1) Scale
Procedure: Prior to conducting our experiment, we made a prediction about the mass of
magnesium oxide that would be produced from the reaction.In order to do this, we had to balance the equation of the reaction between magnesium and oxygen, which yields magnesium oxide. The balanced equation had a molar ratio of 2:1:2, meaning that for every 2 moles of magnesium we had one mole of oxygen and two moles of magnesium oxide. We used stoichiometry to find the mass of magnesium oxide by converting grams of magnesium to moles of magnesium to moles of magnesium oxide to grams of magnesium oxide. Our final answer from this conversion was the predicted mass of the magnesium oxide produced from the reaction.To begin the experiment, we measured the mass of the magnesium and the crucible and recorded it. Then, we set up the ring stand and placed the piece of magnesium in a crucible. We put the crucible on the rubber wire on the ring stand and turned on the Bunsen burner so the tip of the blue cone was just touching the bottom of the crucible. We tilted the lid of the crucible so t here was a gap, because in order for the chemical reaction to happen the magnesium need to be exposed to oxygen. When we saw a bright light glowing from inside the crucible we knew that t he reaction was occurring. After the reaction had run its course, we removed the crucible from the ring stand with a pair of tongs. Then, we carefully took the crucible from our table and we ighed it on the scale and recorded the mass. To find the final mass of the product of the reaction we subtr acted the weight of the crucible from the final weight of the crucible and product. Data:
Mass of Magnesium
Mass of Crucible
Mass of Crucible and
Mass of Product
product .12g
36.37g
36.52
.15g
Analysis: The final mass of the reaction between magnesium and oxygen was fairly close to our
calculated prediction. Our calculations were o ff by about .04 grams, which isn¶t that much, considering using stoichiometry to calculate masses in a chemical equation only gives you an idea of one of the outcomes of the reaction. Also, the atomic masses of elements on the periodic table are approximations that are not explicit for every single atom of that element. Using stoichiometry and balancing chemical equat ions does not necessarily tell you what will happen, but what might happen. In our experiment, it is possible that some of the o xygen that we accounted for in our calculations escaped while the crucible was heating. This could explain why our final mass was less than the o ne we predicted. Although our results weren¶t perfectly accurate, this experiment still shows that the mass of the product, magnesium oxide, is greater than the mass of magnesium because magnesium is reacting with another element, oxygen, and their masses are combining.
