# Analysis Of The Enthalpy Of Formation Of Magnesium Oxide

Improved Essays
In part C, the enthalpy of formation of magnesium oxide was found by adding together three reactions, as shown in the table below. Experiments were performed to obtain the ΔHrxn value of the first two reactions in the table, which were reactions 4 and 5 respectively in the experimental section, while the ΔHrxn for the third reaction in the table was provided. Using the ΔT obtained experimentally, heat energy (q) was determined using the equation q = mCΔT + CΔT where q was the heat, m was the mass of the solution, ΔT was the change in temperature, C was the specific heat of water, and C was the calorimeter constant. The mass was calculated by multiplying the density of the solution, which was 1.01 g/mL, by the volume of solution. When these values were obtained, the number of moles of MgO and Mg were calculated by dividing their recorded masses by their molar masses. Then, ΔHrxn was calculated by dividing the heat energy released in each reaction by the number of moles of MgO in reaction 4 and Mg in reaction 5. The following values were obtained:

Reaction Equation ΔHrxn (kJ/mol)
1 MgO(s) + 2 HCl(aq) ⟶ MgCl2(aq) + H2O(l) -192.295
2 Mg (s) + 2 HCl(aq) ⟶ MgCl2(aq + H2(g) -509.444
3
It can be calculated y subtracting the sum of enthalpies of formation of reactants from the sum of enthalpies of formation of the products. The enthalpy of formation is the ΔHrxn when 1 mole of a compound is formed from its elements in their standard states at 25℃ at 1 atm.2 The change in enthalpy per mole of a reaction was illustrated by part B of the experiment, because the change in enthalpy per mole of HCl or NH4OH was calculated. The standard molar enthalpy of formation was illustrated by part C of this experiment, because the various reactions added up to a reaction that led to the creation of 1 mole MgO from its elements at their standard states. Hence, the ΔHrxn in this reaction represented the enthalpy of

## Related Documents

• Superior Essays

In order to determine this, 25 mL of each of the three fuels will be put into spirit burners. 80 mL of water will then be placed in a small conical flask atop a tripod. The initial temperature of the water and weight of the spirit burner will be recorded. The Spirit burner will be lit underneath the tripod, once left for 1 minute and 30 seconds, calculations will be used in order to calculate heat of combustion and enthalpy. In order to calculate the quantity of heat, the following formula will be used: Q= mC⩟T. Where Q equals the quantity of heat, m equals the mass of water, which is given as 4.18, and ⩟T is the change in temperature. Once this has been calculated, the enthalpy is calculated using the following formula: ⩟H = Q/nOnce these have been calculated, results will be recorded and the most efficient fuel will be determined, via the collected…

• 1461 Words
• 6 Pages
Superior Essays
• Improved Essays

Abstract: In this lab our main objective is to find the empirical formula of MgO, magnesium oxide. To do this first we have to make sure when we burn Mg in the crucible and it reacts to with O. This lab experiment Mg is complicated by another factor. Mg is so reactive that it reacts with N in the air so some of the Mg which is suppose to react with O will react will N instead. This obstacle can be overcome by simply adding water to the Mg3N2 to yield MgOH2 and NH3. This will undo the reaction so O can react with Mg to make MgO and then we can get the empirical formula of MgO.…

• 1338 Words
• 6 Pages
Improved Essays
• Improved Essays

Table 2 and 3: ∆T, the amount of H2O, and amount of MgCl2 used was recorded. This data helped find Q and ∆H.…

• 1562 Words
• 7 Pages
Improved Essays
• Great Essays

Hence, in this experiment, a bomb calorimeter will be used to determine the change in energy and the change in enthalpy of naphthalene. These two values are the goal for the experiment and through the manipulation of the data, they will be achieved. The bomb calorimeter is first used to test three different samples of benzoic acid, in order to settle in on a mean value of the heat capacity of the system, which is then used as a value to solve for the change in energy of naphthalene. After this, the change in enthalpy could be computed and the percent error analyzed for the experiment.…

• 1399 Words
• 6 Pages
Great Essays
• Improved Essays

In this lab, two solid substances, sodium acetate and sodium acetate trihydrate, will be analyzed for the heat of solution for both processes. This allowed the calculation of the molar enthalpy of dehydration of sodium acetate trihydrate. Calorimetry was used to experimentally determine the heat of solution for both reactions.…

• 1267 Words
• 6 Pages
Improved Essays
• Improved Essays

This experiment conducted during lab was designed so that the students would be able to formulate the hydrate’s empirical formula after heating and observing the effects of heating a hydrate salt. By taking careful measurements and the usage of stichometry, the students should be able to accomplish their goals.…

• 1196 Words
• 5 Pages
Improved Essays
• Improved Essays

In this experiment, we mixed different amounts of reactants and measured the volume of O2 they produced so that we could determine the rate and order of the reaction. Three trials were done, the first trial acted as a baseline, then the following two trials each varied the concentration of a single reactant, allowing us to calculate the order of the reaction. Additionally, the temperature of the solution was changed to see what effect that would have on the rate. Using this information the activation energy for this reaction could be calculated and compared to the activation energy of the uncatalyzed reaction.…

• 882 Words
• 4 Pages
Improved Essays
• Improved Essays

By adding Hydrochloric acid into solid Magnesium, in Data table #2, when Hydrochloric acid was first been added to solid Magnesium, the ribbon immediately start to bubble and producing fumes at the same time with a burning sound. Magnesium start to turn into a white liquid form. After the bubble start to disappear, more Hydrochloric acid was added, and the reactions repeats. Until none of the shiny silver Magnesium ribbon can be seen, and there is no more bubble, the reaction is over.…

• 877 Words
• 4 Pages
Improved Essays
• Improved Essays

The change in the reaction mixture occurred when the temperature got to a 100˚C. The mixture had turned a very dark color. The mixture started out blue and it changed to an almost black color. The mixture was continued to heat for an additional 5 minutes and then it was cooled down to room temperature. When the reaction mixture was cooled, solids started to form on the sides of the beaker. The solids were black and chunky and there was some liquid left in the beaker. The products that were formed in this reaction by copper hydroxide were copper oxide and water. This reaction that took place was a…

• 1320 Words
• 6 Pages
Improved Essays
• Improved Essays

Bomb Calorimetry is a valuable instrumentthat measures the energy content of food and chemicals. A substance inside of the Bomb Calorimetry goes through a combustion reactions which take place inside of a closed stainless-steel container surrounded by water. In this experiment, benzoic acid and Tollhouse chocolate chips will release energy through a combustion reaction inside of the stainless-steel container. The combustion reaction that occurs will cause the water surrounding the system to increase. To determine the combustion reaction’s energy change from the change in temperature, the heat capacity of benzoic acid must be calculated. This requires the benzoic acid to be burned in the Bomb Calorimetry. Afterwards, Tollhouse chocolate chips will then be utilized by the bomb calorimetry to calculate the energy content of a serving of chocolate chips. The heat of the system and the change in the internal energy for the system will be discovered. The value will then be compared to the nutritional value on the package of the Tollhouse chocolate chips.…

• 625 Words
• 3 Pages
Improved Essays
• Improved Essays

When the experiment was conducted, the magnesium was heated with a bunsen burner for about 6 minutes only. However, the complete reaction could have required more time for all of the magnesium to react and produce magnesium oxide. As calculated in Figure 1, the expected percent composition of magnesium in magnesium oxide is 60.32% and according to the law of definite proportion3, this percentage should be constant. Given this information, the amount of magnesium oxide that can be produced using 0.06g of magnesium can be determined. As shown in Figure 7, 0.1g of magnesium oxide could have been produced by 0.06g of magnesium. However according to Table 1, the product, magnesium oxide, was only 0.09g. This denotes that not all of the magnesium reacted with oxygen. Therefore, the results (mass of the product) of this experiment are incorrect. For future experiments, magnesium should be heated for a longer time period to ensure that all the magnesium has…

• 917 Words
• 4 Pages
Improved Essays
• Improved Essays

The burning of magnesium in open air causes a chemical reaction that forms the compound, magnesium oxide. This reaction occurs due to the heat that provides energy to activate the reaction. A blinding white flame will burn as the reaction occurs. In this lab, magnesium is burned in an open crucible over a Bunsen burner several times until the magnesium ceases to burn. This process allows for the magnesium to completely react with the oxygen found in the open air, forming the chemical compound magnesium oxide. However, our lab did not provide us with the hypothesized results, as no reaction occurred when the magnesium was burned, potentially due to an error in the process.…

• 1193 Words
• 5 Pages
Improved Essays
• Improved Essays

To start the lab, .7 grams of copper was measured out and at the end, the total amount of copper was .73 grams. Throughout the five reactions, the theoretical yield was calculated for whatever substance was being created. Those masses (listed in order) include: 2.07 grams CuNo3, 1.08 grams Cu(OH)2, .88 grams CuO, 1.49 grams CuCl2, .70 grams Cu. Then,…

• 1243 Words
• 5 Pages
Improved Essays
• Superior Essays

These values were then converted into enthalpy values in joules per mole. The enthalpy values for the hydrated crystals show a trend of positive values while those of the anhydrous crystals show a trend of negative values. The total enthalpy, however, is positive. Enthalpy is related to the spontaneity of a process. The entropy of the process was determined from the transition enthalpy and temperature values. Based on the positive enthalpy and entropy values, the reaction appears nonspontaneous.…

• 1185 Words
• 5 Pages
Superior Essays
• Improved Essays

The heat capacity of the calorimeter was determined to be 19.3 J/˚C. For reaction 1, which was between NaOH and HCl, the enthalpy of the reaction was -45.7 kJ/mol. For reaction 2, which was between NaOH and NH_4 Cl, the enthalpy of the reaction was -8.67 kJ/mol. For reaction 3, which was between HCl and NH_3, the enthalpy of the reaction was -46.2 kJ/mol. The enthalpy of reaction 3 determined by Hess’s Law and the results of reactions 1 and 2 was -37 kJ/mol. The percent error for the enthalpy of reaction 3 acquired from the in-lab procedure was 13%. The percent error for the enthalpy of reaction 3 acquired using Hess’s Law was 30%. One significant correlation between all of the enthalpies calculated is that all of them are negative, showing that heat was lost in all of the reactions, making them exothermic. As for the percent errors, there was less error when the data acquired was recorded by observing a performed reaction. Guessing the enthalpy using Hess’s Law and the results of the other reactions introduced more error into the calculation. One source of error could be that when the reactant was being poured into the calorimeter, leaving the lid open for too long let too much heat loose, which would affect the results. This would have affected reactions 1 and 2, and that increased percent error would affect the enthalpy of reaction 3 calculated using Hess’s Law. It affected the enthalpy calculated from the in-lab results less because the was only one reaction where that error could affect the…

• 840 Words
• 4 Pages
Improved Essays