Enthalpy change of magnesium in combustion Rui Shen Chemistry 4U – Ms .Brazier 2/28/2013 Introduction: Hess ’s law is a terminology in chemistry named after Germain Hess‚ a Swiss-born Russian chemist and physician who published it in 1840. The law states that the total enthalpy change during the complete course of a reaction is the same whether the reaction is made in one step or in several steps. Enthalpy cannot be directly measured‚ but rather the change in enthalpy. Enthalpy is described
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The Dissolving of Solid Sodium Hydroxide in Water Procedure: 1. Measure out approximately 200 mL of distilled water and pour it into the calorimeter. Stir carefully with a thermometer until a constant temperature is reached. Record the volume of water and the constant initial temperature of the water on your data table. 2. Place a plastic measuring trough on top of the digital balance‚ and then zero the balance (press the tare button) so that the mass of the trough will be "ignored" and
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Thermodynamics- Enthalpy of Reaction and Hess’s Law December 5‚ 2011 Kylie Case‚ Emma McKee‚ Rebecca Smith Purpose: In this lab‚ the purpose was to verify Hess’s Law. Theory: Four main topics were covered during this experiment including enthalpy of reaction‚ heat of formation‚ Hess’s Law‚ and calorimetry. The first being enthalpy of reaction‚ ΔHrxn‚ which is the heat or enthalpy change for a chemical reaction. The energy change is equal to the amount of heat transferred at a constant
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by Bomb Calorimetry Cameron Fowler CHEM 457: Lab Section 4 Submitted: 11/4/10 Lab Group #3: Michael Hyle Neil Baranik Tim Riley Abstract: The enthalpy of combustion of naphthalene was experimentally determined to be -5030.44 ± 78.98 kJ/mol which was a 2.5% error from the literature value of -5160 ± 20 kJ/mol.2 The theoretical enthalpy of combustion of solid naphthalene was calculated to be -6862.68 kJ/mol using bond energies for the gaseous molecules‚ the heat of vaporization of liquid
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Energetics Worksheet 1. Calculate a value for the Lattice Energy of Calcium Chloride from the following data. Draw energy cycles Std. Enthalpy of Formation of CaCl2 = - 795 kJ/ mol Std. enthalpy of atomisation of calcium = + 177 kJ/mol Std. enthalpy of atomisation of Chlorine = +121 kJ/mol 1st ionisation energy of calcium = +590 kJ/mol 2nd ionisation energy of calcium = +1100 kJ/mol Electron Affinity of chlorine = -364 kJ/mol 2. Draw Born-Haber cycles and calculate the L.E. of Cu2O and CuO
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Joshua McMahon IB Chemistry Matt Chase 3A 11/5/14 Finding the Molar Enthalpy Change of sodium bicarbonate by using Hess Law Research Question By using Hess’ Law‚ can the Molar Enthalpy Change of sodium bicarbonate be calculated? Hypothesis If we are attempting to determine the enthalpy change of the thermal decomposition of Sodium Bicarbonate‚ then Hess’s Law will be will be the most effective. Introduction Sodium bicarbonate‚ more commonly known as baking soda‚ has many uses in todays
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is used to measure amounts of heat transferred to or from a substance.2 The difference of temperatures was used to calculate the heat energy given off by each sub-reaction. These values were solved by using Hess’s Law which determined the overall enthalpy changes of the neutralization reaction and MgO formation. Hess’s Law states that the heat evolved or absorbed in a chemical process is the same whether the process takes place in one or in several steps.1 If this experiment were to be completed again
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Discussions and Scientific Explanations The first goal of this project was to first construct a calorimeter. The second goal was to measure the heat capacity of the constructed calorimeter. The third and fourth goal was to determine what reactions were to be investigated and what variations of the reactions would be studied. The two requirements that were kept in mind while creating the calorimeter were that it should be a good insulator‚ meaning that it does not allow for the transfer of heat
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Hess’s Law Mengyuan Wu (Millie) 7 January‚ 14 Aim: The purpose of this experiment is to determine the enthalpy change for the reaction: Introduction: It is impossible to measure the enthalpy change for this reaction directly because the process cannot be controlled. However‚ you can calculate this enthalpy change by using the Hess’s Law. Pre- lab Calculations: Calculation 1: Required Masses for Reaction The ratio of and is required to be 1:100 for Table 1: Calculation
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A simple depiction is a hybrid of both of Kekulé’s structures (Scheme 1). In order to confirm the structure of benzene‚ the enthalpy of Kekulé’s structure must be determined and then used to calculate the resonance stabilization energy (RSE) for benzene. If the RSE is greater than zero‚ there is additional stabilization that must come from something besides the enthalpy that corresponds to the isolated double bonds. In modern chemistry‚ this extra stabilization stems from a “resonance hybrid” of
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