Introduction Enthalpy change‚ ΔH‚ is defined as the heat output of a system as it goes through a reaction under constant pressure. It is an important aspect of thermochemistry‚ which is the study of energy changes during a chemical or physical reaction . When we calculate enthalpy change‚ we always assume that the pressure is constant. We are able to calculate enthalpy change numerous ways‚ notably by the increase in heat‚ Q‚ given by an exothermic reaction or the heat absorbed by an endothermic
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Calculation on the molar enthalpy change of a neutralization reaction Principle H2SO4(aq)+2NaOH(aq)=Na2SO4(aq)+2H2O(l) The reaction is a exothermic reaction‚ when the heat released by it is absorbed by water‚ the temperature of the water increases. The heat produced by the reaction can be calculated if it is assumed that all the heat is absorbed by the water. Heat change of reaction=-heat change of water =-mH2O×cH2O×△TH2O As the water has gained the heat produced by the reaction‚ the heat change
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Enthalpy of Neutralization Introduction Energy changes always accompany chemical reactions. If energy‚ in the form of heat‚ is liberated the reaction is exothermic and if energy is absorbed the reaction is endothermic. Thermochemistry is concerned with the measurement of the amount of heat evolved or absorbed. The heat (or enthalpy) of neutralization (∆H) is the heat evolved when an acid and a base react to form a salt plus water. Eq. 1 HNO2(aq) + NAOH(aq) → NaNO2(aq) + H2O(l) + Q Q in the
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Determining the enthalpy of neutralization by calorimetry Anam Iqbal Partner’s name: Danielle Hodgson TA’s name: Karinna Section # 003 Due date: November 24‚ 2009 Introduction The purpose of the experiment is to determine the enthalpy of neutralization reactions by calorimetry. Calorimetry‚ is the science of measuring the amount of heat. All calorimetric techniques are therefore based on the measurement of heat that may be generated (exothermic process) or consumed (endothermic process). The
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Calorimetry: Enthalpy of Neutralization Introduction: The purpose of this lab experiment was to determine the molar concentration of the unknown HCl by using a coffee cup calorimeter. A coffee cup calorimeter is made of Styrofoam cups with a thermometer that is placed from the top and into the calorimeter to measure the temperature as the reaction happens. The Styrofoam cup used for the calorimeter creates an isolated system as it acts as a heat insulator between the cup and the surrounding
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DETERMINATION OF ENTHALPY CHANGE OF NEUTRALIZATION IA Criteria Assessed: DCP CE MS Introduction When an alkali neutralizes an acid‚ a salt and water are formed. Aqueous hydrogen ions (H+(aq)) from the acid react with the hydroxide ions (OH- (aq)) from alkali‚ forming water. The identity of salt will depend on the nature of the acid and alkali used. H+(aq) + OH- (aq) → H2O(L) The combination of H+ and OH- ions in this way releases energy. In this practical‚ the enthalpy changes accompanying
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Hess Law Lab DESIGN Aspect 1: Problem: What is the molar enthalpy of formation of magnesium oxide? Variables: Manipulated: None Responding: None Controlled: Isolation of calorimeter‚ concentrations of substances involved. Aspect 2: Background Information: Assumptions: Specific heat capacity of water‚ we assume that the acid has the same qualities as water including heat capacity‚ and we assume the enthalpy of formation for magnesium oxide from the data booklet for theoretical
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15.2 Born-Haber Cycle Our calculations of enthalpies so far have involved covalent substances. Now we need to look at the enthalpy changes involved in the formation of giant ionic lattices. Lattice enthalpy is defined as either the: ’the enthalpy change that occurs when one mole of a solid ionic crystal is broken into its ions in the gaseous state‚ at standard temperature and pressure. Because all the bonds in the ionic lattice are broken‚ it is an endothermic process‚ ∆H is positive. ’ The
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Heat of Neutralization: Lab Report In part A of this lab I determined the heat capacity of a calorimeter made out of two Styrofoam cups nesting together with a cardboard top containing a hole in the middle. First I placed 50 mL of water in the calorimeter‚ waited five minutes for the water to reach equilibrium‚ and used the computer’s temperature instrument to record the final temperature of the system. Next I heated 50 mL of water in a 250 mL beaker until the water reached 43.1 C (approximately
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the Enthalpy of a Chemical Reaction All chemical reactions involve an exchange of heat energy; therefore‚ it is tempting to plan to follow a reaction by measuring the enthalpy change (∆H). However‚ it is often not possible to directly measure the heat energy change of the reactants and products (the system). We can measure the heat change that occurs in the surroundings by monitoring temperature changes. If we conduct a reaction between two substances in aqueous solution‚ then the enthalpy of
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