Heat of Formation of Magnesium Oxide

ObjetiveTo correct the shake up constitution of MgO (Magnesium Oxide) development Hesss Law, which states the kindle within a chemical reaction is autarkical of the pathway between the initial and final states.IntroductionChemical reactions require warmth talent to complete, c anyed an endothermic reaction, or produce hot up cleverness, and thus called an exothermic reaction. The heat energy produced by such reactions cornerstone be measured development a calorimeter, a piece of equipment that can isolate the reaction in an insulated container. Using the calorimeter one can then regard the rise and inclination in temporaryerature of the reaction. When this temperature change is multiplied by the heat contentedness, the amount of heat needed to raise the temperature of a body by one degree, we can measure the change in converting our initial components (reactants) to their respective products.In this experiment we bequeath measure the amount of heat released from 3 r eactions (HA HB HC) and depend the check of all 3 reactions to set apart HT, which will give us the heat formation of MgO. If Hesss law holds true and barring negligible experimental computer error, the pathway we use to determine HT should have no tutelage on our calculation matching the accepted calculation of MgO.MethodsAs per lab manual we used a calibrated calorimeter ( utilise a rounded end thermometer so as to not puncture a hole in the calorimeter) to determine the heats of reaction for Magnesium (Mg) with Hydrochloric Acid (HCl) and Hydrochloric Acid with Magnesium Oxide (MgO). Then use mathematical formulas we were able to calculate the heat formation of MgO, which is measured in kJ/Mol. Since both reactions are in dilute piss solutions ofHCl it was necessary to dwell the heat capacity of water, but because some heat would be transferred to the calorimeter whose heat capacity was unknown, we had to record a correction factor (x) based upon the limited heat of wa ter exploitation the equation m(h2o)+XCwater+water=-1(m(ice water)Cwatertice water).We then record the mass (m) of elbow agency temperature water and ice water each in a respective cup and then poured the ice water into the room temperature water and recorded the temperature change. By knowing (x) we could then calculate the heat of reaction for Mg with HCl (HA kJ/mol) and for HCl with MgO (HB kJ/mol) using the equation q=m(HCl+X)C T where m is the mass of the reactant used with Mg + X, C is the heat capacity of water (4.184 J/gC), and T is the total temperature change in each reaction. Using the results of these calculations and Hesss law we can then determine the heat formation for MgO.DataAll mass readings are given in units of grams (g), and all temperature readings are given in degrees Celsius (C).Part AMass of the Calorimeter + RoomTemp Water (g)48.08Mass of room temp water (g)46.29Mass of Cal + room temp water + icewater (g)115.40Mass of ice water (g)67.32Temp of room temp water (C)42.4Temp of the ice water (C)0.1Final temp. of room temp water (C)17.3Change in temp of ice water (C)17.2Change of temp of room temp water (C)-25.1Mass of the calorimeter (g)1.79Part 2AMass of Calorimeter (g)1.79Mass of Cal + HCl (g)103.55Mass of HCL (g)101.76Mass of Mg (g)0.5Temperature of HCl (C)20.3Final temperature of HCl + Mg (C)42.0Change in Temperature (C)21.7Part BMass of Calorimeter (g)1.79Mass of Cal + HCl (g)101.76Mass of HCl (g)99.88Mass of MgO (g)0.8Temperature of HCl (C)20.3Final temperature of HCl + MgO (C)25.8Change in Temperature (C)5.50Results and DiscussionTo calculate X using the equation m(h2o)+XCwater+water=-1(m(ice water)Cwatertice water) the variable X must be isolated and doing so we were than able to calculate the correction factor found on the calculations of the calorimeter correction factor, X was determined to be 0.158 g. Then using the equation q=m(HCl+X)C *T, where q is equal to the amount of energy given off, and than calculating the rate in -kJ/Mol (because these are exothermic reactions) we were able to determine HA and HB.qA=m(HCl+X)C xTqA=(101.76 g + 0.158 g) x 4.184 J/gC x 21.7CqA= 9250 J = 9.250 kJ 9.253602176qB= m(HCl+X)C xTqB=(101.76 g + 0.158 g) x 4.184 J/gC x 5.50CqB=2350 J = 2.350 kJTo then calculate the heat formation of MgO HT, the sum of all the reactions must be determined including HC, the heat formation of water, which is already predetermined to be -285.8 kJ/mol. However to determine the proper equation for HT, the stoichiometric equations must first be balancedTherefore the heat formation of MgO was determined to be -618.35 kJ/mol. According to the textbook, the accepted value for HT=-601.8 kJ/mol. To determine the the true of the calculation we can determine the % errorAs far as accuracy goes a percent error of 2.75% is rattling acceptable. Because the methods of the experiment were conducted using a crude calorimeter I would have expected the percent error to be higher, assuming that because of its construction it would not have very high efficiency.I would expect that any error that might have occurred happened during the transferral from one cup to another. Because the substances were transferred so quickly and taking into account the procedure of seconds that it took to replace the thermometer to begin recording data again it is possible that energy was either missed in the transfer or energy was lost before the recording was actually able to begin.ConclusionIn this lab we were able to determine the heat of formation of MgO using a simply constructed calorimeter, which was found to be -618.35 kJ/mol.