Determining the Empirical Formula of Magnesium Oxide Lab Report
Observation and Results
Mass (g)
Mass of clean, empty crucible and lid
54.3464 g
Mass of crucible, lid and magnesium
54.3919 g
Mass of crucible, lid and magnesium oxide
54.4093 g
Table 1: Experimental Masses of Equipment, Reactants and Products
Masses of relevant equipment, reactants and products were recorded to be used later in calculations to determine the percent composition and empirical formula of magnesium oxide.
Mass of magnesium
0.04550g
Mass of oxygen
0.01740g
Mass of Magnesium Oxide
0.06290g
Experimental - Percent Composition of Magnesium
72.3370%
Experimental - Percent Composition of Oxygen
27.6630%
Moles of Magnesium
0.001871657 moles
Moles of Oxygen
0.0010875
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It was determined by using the mass of the products divided by the mass of the product, then multiplied by 100% to get the value in a percent. The percent composition of the product concluded to there being approximately 72.3370% magnesium elements and 27.6630% oxygen elements in the compound. Percent composition shows the mass percent of an element in a compound in relation to the other elements. Then calculating number of moles and dividing each mole by the smallest from the two, created the subscript of the experimental empirical formula. The experimental empirical formula resulted to be Mg3O2. Empirical formula is derived from experimental observation, not theory. It expresses the simplest ratio that the elements are combined in however, it is not necessarily correct information about the number of atoms in a molecule and does not express the quantity of atoms in the sample. The ratio of magnesium cations to oxygen anions is 3:2. The theoretical empirical formula is MgO. This formula shows the number of elements expected to be in the compound and the simplest ratio of the elements in the compound. This is determined because this is a synthesis reaction of magnesium and oxygen. Magnesium has a 2+ charge while oxygen has a 2- charge, when the charges are crossed, it creates the compound, MgO. To calculate the mass percent or theoretical percent composition, …show more content…
This created a distance from the hot surface of the crucible from the Bunsen burner thus, not allowing the experiment to conduct. With the magnesium not touching the hot surface, there is a lack of energy for the chemical reaction to happen and not produce magnesium oxide. Another possible experimental error is that when crushing the magnesium oxide to a fine powder with a glass rod, water was used to wash off the magnesium oxide on the rod to get a more accurate mass. However, due to the solution being hot from the Bunsen burner, adding water created evaporation and also resulted in the solution to spill on to the lab bench which affected the mass and calculations. Also, connecting to this experimental error could be that the glass rod was not washed properly with the distilled water leaving some of the fine powder thus, leading to an approximate mass rather than an exact mass. The solution that was produced was not a 100% magnesium oxide as the magnesium strip was reacting to the air and the air does not have 100% oxygen atoms only. Another error for this experiment could be the unequal supply of oxygen. For this experiment to be more successful, there should be excess amount of oxygen entering the magnesium strip. Another ways to make the lab better is by following the procedure and keeping full attention to minor detail
) Suppose that some magnesium oxide smoke had escaped during the investigation, the Mg:O ratio would have increased from 58% to 72%. The final mass of MgO would have decreased because the magnesium oxide smoke is part of the product and when some of it escapes, it decreases the final mass.
Mole of chlorine : 1.0217g - .221g - .3946 g = .4061 g of chlorine
The theory that C.M. Berthollet introduced about the composition of a compound was that a compound has an infinite number of compositions depending on the proportions of the components that were used in its preparation. His theory satisfies the results obtained from the whole class. Since every group had a different amount of magnesium they must also have had a different composition of magnesium in the compound formed, magnesium oxide.
The first experiment is about the combustion of magnesium after which the ash is formed.
Based on my and other classmates' observations and results it can be proved that every time magnesium combines with oxygen to form Magnesium oxide the percent composition for magnesium will be 60.31% and for oxygen it will be 30.69 % (the results achieved by experiments are
In this lab, a calorimeter was used to find the enthalpy of reaction for two reactions, the first was between magnesium and 1 molar hydrochloric acid, and the second was between magnesium oxide and 1 molar hydrochloric acid. After the enthalpy for both of these were found, Hess’ law was used to find the molar enthalpy of combustion of magnesium, using the enthalpies for the two previous reactions and the enthalpy of formation for water. The enthalpy of reaction for the magnesium + hydrochloric acid reaction was found to be -812.76 kJ. The enthalpy of reaction for the magnesium oxide + hydrochloric acid reaction was found to be -111.06 kJ. These two enthalpies and the enthalpy of formation for water were manipulated and added together using Hess’s law to get the molar enthalpy of combustion of magnesium. It was found that the molar enthalpy of combustion of magnesium was -987.5 kJ/mol. The accepted enthalpy was -601.6 kJ/mol, which means that there is a percent difference of 64%. This percent difference is very high which indicates that this type of experiment is very inefficient for finding the molar enthalpy of combustion of magnesium. Most likely, a there are many errors in this simple calorimeter experiment that make it inefficient for finding the molar enthalpy of combustion of magnesium.
Magnesium ribbon was reacted with Hydrochloric acid in three different experiments to determine the charge on a metal ion. After running multiple tests in the three different procedures, the Crystallization method proved to be the best method for determining the charge of the metal ion by using mole to mole ratio.
There is a very easy way to find the empirical formula of a compound using the mass percentages found through elemental analysis. First, convert the mass percentages to a mass, assuming that the compound is 100g. Then convert each mass into moles using the molar masses. Then divide each of these moles by the element with the smallest amount of moles. That is the ratio of the empirical formula. Just make sure that the numbers are in whole numbers, if not, multiply by common denominators to get all of them to a whole number (3).
| After ignition of magnesium light and toxic fumes are made, and white powder (2MgO or Magnesium Oxide) is left over.
A1.Work under the hood! With a pair of tongs, hold a strip of magnesium in a bunsen burner flame. Do not look directly at the flame. Save the ash in a small beaker for the next procedure. If magnesium is substance "A" in the general equation, what is "B"?
In the experiment the magnesium reacts with the hydrochloric acid to create magnesium chloride and hydrogen. The balanced formula for this is:
The goal of this experiment was to determine the empirical formula for a hydrate of magnesium sulfate and water. The technique that was used was measure the mass of the hydrate and then apply heat to evaporate the water. Then determine the mass of water that was in the hydrate and the mass of the remaining magnesium sulfate. The equation for the hydrate is determined by calculating the mole to mole ratio of the water and the anhydrous. The resulting formula will be formated as: MgSO4*_H2O
As we learned before on how to determine the empirical formula of a compound based on the test and also chemical analysis on it. Hence this experiment is mainly goes around with how to determine the empirical formula of Magnesium Oxide following various tight procedures in order to get the knowledge and apply it onto another compounds. We are investigating the empirical formula of Magnesium Oxide in this experiment.
Firstly, after removed from the Bunsen burner, the crucible was not given time to cool down before being weighed. Weighing a hot crucible can affect the accuracy of measurements by making the crucible appear to weigh heavier, causing the results to be overstated. Secondly, as state in the paragraph above, both samples did not weigh exactly 2g. In trial 1, the sample weighed slightly less than 2g but in trial 2 the sample weighed slightly more than 2g. Consequently, the net weight for the solid in trial 1 was understated and the net weight for the solid in trial 2 was slightly
Introduction: The main purpose of this experiment is to determine the empirical formula of zinc iodide, and in addition, validate the law of conservation of mass by precisely determining the quantities of reactants and products. Empirical formula is the simplest type of chemical formula. The simplest ratio of the number of atoms of each element in the compound is determined by the empirical formal of a compound. Typically the ratio provided by the empirical formula contains whole numbers. On the other hand, there are molecular formulas in which gives the definite number of atoms of the element.