Empirical Formula of Magnesium Oxide - Lab Report Example

Empirical Formula of Magnesium Oxide Introduction Magnesium is an alkaline earth metal that can react with to form Magnesium Oxide (Shipman, et al., 2015). Magnesium is a greyish-white metal that burns with a blinding glare. The atomic number of Magnesium. In the 18th century, the French chemist Antoine Lavoisier was busy performing very many combustion experiments. After some time, Lavoisier realized that even though the reaction characteristics of the materials varied the total mass of the products was similar to the total mass of the reactants. Lavoisier summarized his observations in the law of conservation mass, which states that mass is neither created nor destroyed (Erdey, et al., 2013). The experiment to test the empirical formula of Magnesium is based on the principles of the law of conservation of mass. The formula of Magnesium can be predicted with the use of atomic theory, which leads to the electron structure of Magnesium and Oxygen atoms. John Dalton’s atomic theory can be used to determine theoretically the formula of Magnesium Oxide (Joesten, et al., 2007). First, it is necessary to understand the chemical formula is a chemical composition of a given substance in a single basic unit. Magnesium and Oxygen each have a valency of 2, which means one Magnesium atom is required for every single atom of Oxygen (Shipman, et al., 2015 p. 596). The aim of the experiment is to compare the empirical formula of Magnesium Oxide developed after the experiment with the formula developed during the experiment. Prior to the experiment, energy is needed to break the metallic and covalent bonds between Magnesium atoms and Oxygen molecules respectively. The reaction that occurs between Mg and O2 is an exothermic reaction. Breaking the bonds leads to energy release (Khopkar, 2004). The following figures show the kind of bonds that are formed in Magnesium atoms and Oxygen molecules. Figure 1: Metallic Bond (Source: ReviseScience.co.uk) Figure 2: Oxygen Covalent Bond (Source: Ron Kurtus) Gravimetric Analysis Theory Gravimetric analysis the use of mass measurement to determine the amount of the analyte. Magnesium is a highly reactive metal, which is why it should be solid (Erdey, et al., 2013). It is paramount to limit the amount of oxygen to reduce the rate of reaction (Zumdahl & DeCoste, 2013). The use of magnesium strips ensures the whole surface of the metal is exposed to oxygen. A gravimetric analysis demands a step by step of measurement of mass before and after the reaction. The magnesium is weighed before the reaction and the final product after the reaction is also weighed. The weighing helps in determining the exact mass of oxygen that combines with Magnesium in the reaction. Since both Magnesium (Mg2+) and Oxygen (O2-) have a valency of 2 the reaction will go as follows: 2Mg (g) + O2 (g) 2MgO (s) The reaction needs the energy to break the covalent bond that holds the two oxygen atoms and the metallic bond in Magnesium atom. Hypothesis Magnesium will react with Oxygen in 1:1 ratio. The resulting product should be white (Zumdahl & DeCoste, 2013). Also, Magnesium will react with Nitrogen to produce a black substance. It is because Magnesium is a highly reactive metal. Health and Safety Tips: Magnesium is highly flammable, which means it can easily burst into flames. Therefore, it is imperative to keep one’s eye very far from the crucible during the experiment. In addition, Magnesium has a blinding glare when it burns, which is very harmful to the eyes. The ignition of the Magnesium can be prevented by closing the lid. The Bunsen burner will produce so much heat during the experiment. One should keep a considerably safe distance from the Bunsen burner. One should wear the safety glasses to prevent the damage that can be caused by flying sparks if the Magnesium is ignited. The crucible should be intact because if the Magnesium falls in the Bunsen burner it might explode. Fragmentation of Magnesium can irritate the skin and cause severe burns. It is paramount for one to adhere to all safety precaution. Desist from touching the crucible while it is heating or after the heating has immediately ended. The substances being heated should always be handled using tongs or any other handling equipment advised by the technician. Apparatus and Chemicals The experiment requires a Tripod, Bunsen Burner, Pipeclay Triangle, lid, and Crucible, clean Magnesium ribbon, Crucible tongs (heatproof), and safety glasses. Procedure An empty crucible and the lid was taken and placed on the balance. The mass was recorded. A magnesium ribbon that is 10cm ribbon long was folded into a spiral shape and place carefully on the bottom of the crucible. The crucible was then covered and weighed using the same balance. The mass of the crucible plus the lid and the Magnesium ribbon was recorded. A tripod was then set up, and a pipeclay triangle placed on top of it. The apparatus was organized in a manner that allows the crucible and the magnesium to be in contact with hottest part of the Bunsen burner flame. The crucible was heated for 4 minutes, and then the crucible lid was removed using the tongs. The bunsen burner was then removed. A period of 45 seconds had passed before the crucible lid was lifted to check the product. A record was made upon the sighting of white smoke trying to escape. The crucible was then placed on pipeclay and the whole process repeated two more times. The fourth heating process was done with the lid off. Caution was practiced to ensure the crucible can be immediately covered if the Magnesium starts to burn. The crucible was placed on the heatproof mat facing upside down. The products were cooled, and the re-weighed. The heating was done to ensure the recorded was constant. Results Table Item Mass (g) Crucible + Lid 25.04 Crucible + Lid + Magnesium 25.18 Crucible + Lid + Magnesium Oxide 25.29 Magnesium 0.14 Oxygen in Magnesium Oxide 0.11 Calculation The Ar values are Magnesium = 24 and Oxygen = 24 From Experiment: Mg = 0.14 0 = 0.11 So, in Magnesium Oxide there is Mg= 0.14/24 = 0.005833 mole O = 0.11/16 = 0.006875 moles Therefore, the formula of Magnesium Oxide is based on the ratio 0.005833: 0.006875 O.005833 ÷ 005833 = 1 and 0.006875 ÷ 00.5833 = 1.178639 ̴ 1.18 The ration is 1:1.18, which means the formula for Magnesium Oxide is MgO 1.18 based on the experiment. Percentage Error It is calculated based on the following equation: % error = Limit of accuracy of equipment x 100 Quantity measured The limit of accuracy is ½ of 0.001g Item Percentage Error (%) Crucible + Lid (25.04) 0.0019968 Crucible + Lid + Magnesium (25.18) 0.0019857 Crucible + Lid + Magnesium Oxide (25.29) 0.0019771 Total 0.0059596 The percentage error for the experiment is 0.0059596 Discussion The reaction between Magnesium and Oxygen is very slow at room temperature. The Magnesium was heated in the crucible to increase the rate of reaction. The pipeclay triangle was used to make sure all the heat is directed at the center of the crucible. It helped in prevented the heat from spreading out. The magnesium was folded into a spiral shape to make sure all of it is exposed to air. It made it possible for Oxygen to react with the surface of the metal. Approximately 10cm of Magnesium ribbon to give a reasonable weight, which will help in the maintenance of accuracy in the experiment. After heating, it is advisable to wait to avoid the white smoke, which contains Magnesium Oxide. The extra heating with the lid off was done to make sure metal had increased access to the air. The extra time heating to constant mass is to ensure that all the metal reacts. The non-quantifiable errors in the experiment are the amount of the product that escapes when the lid is opened (Anon., 2009). It is also possible that Magnesium reacted with Nitrogen to produce Magnesium Nitride (Zumdahl & DeCoste, 2013). 3Mg (s) + N2 (g) Mg3N2 (s) Therefore, it is possible that the product had some Magnesium Nitride. An elaborate process on how to reduce the error of Magnesium Nitride is available. It is not paramount to note that the changes of all Magnesium reacting is minimal. The experiment is rife with too many limits, which also affect accuracy. In my experiment, the crucible had some small residues after heating. The residues cannot be fully accounted in the mass of the products. It is also another source error. The products of the experiment was a mixture of white solid and gray solid. The white solid is the Magnesium Oxide whose formula was being empirically tested. Magnesium Nitride is known to be yellow, which means it cannot be the gray solid. Possibly, the gray solid is a mixture of Magnesium Oxide and Magnesium Nitride. The experiment was completed successfully without major mishaps. Conclusion Caution was prioritized during the experiment to guarantee personal and environmental safety. According to the experiment, the formula of Magnesium Oxide is MgO 1.18, which is near to the theoretical formula that is MgO. The percentage error incurred during the experiment stands at 0.0059596. The main sources of error are the failure to react all the Magnesium, the formation of Magnesium Nitride, and the small amount of the product that is likely to escape when the lid is opened. References Anon., 2009. Experiments in general chemistry 2009. Taipei: National Taiwan University Press. Erdey, L., Svehla, G. & Buzás, I., 2013. Gravimetric analysis ... 2,. Oxford, London, New York: Pergamon Press. Joesten, M. D., Hogg, J. L. & Castellion, M. E., 2007. World of Chemistry: Essentials. 4th ed. Australia; Canada: Thomson Brooks/Cole. Khopkar, S. M., 2004. Basics of Analytical Chemistry. 2nd ed. Mumbai: New Age International. Shipman, J., Wilson, J., Higgins, C. & Torres, O., 2015. An Introduction to Physical Science. 14th ed. Boston, MA: Cengage Learning. Zumdahl, S. S. & DeCoste, D. J., 2013. Chemical Principles. 7th ed. Belmont, CA: Brooks/Cole, Cengage Learning. Read More