# Heat of Reactions and Enthalpy Changes Essay

4002 WordsMay 19, 201317 Pages
Khalifa University of Science, Technology and Research Laboratory Experiment No. 7 Experiment Title: Heat of Reactions and Enthalpy Changes Aims: To determine the heat of solution and heat of neutralization Objectives:  On completion of this experiment the student should be able to: Identify the definitions of calorimetry, specific heat capacity, heat of reaction, heat of solution and heat of neutralization Calculate the heat of solution and heat of neutralization To test Hess’s law by measuring the enthalpy changes for the same net chemical reaction carried out by two different paths To make an approximate estimate, by an indirect measurement of the enthalpy change for dissociation of water into hydronium and hydroxide ions    CHEM 115 - Lab #7: Heat of Reactions and Enthalpy Changes Page 1 of 20 Khalifa University of Science, Technology and Research BACKGROUND Calorimetry is the measuring the heat of chemical reactions or physical changes. This word is derived from the Latin word calor, meaning heat. It is performed with a device called a calorimeter. Calorimeter must be a good insulator that insulate the substance so well until no heat would be lost or gained from the surroundings. The calorimeter used in this experiment is two nested Styrofoam coffee cups. Well, it is far from an ideal calorimeter but we will assume that no heat flows into or out of it. Thermochemistry deals with the thermal energy changes that accompany chemical reactions. These energy changes usually are called heat of reactions. When the reaction is carried out at constant pressure, the heat of reaction is called enthalpy change, ∆H. A reaction that produces heat is said to be exothermic .In an exothermic reaction the enthalpy of the products is less than the enthalpy of the reactants. If we define the change in enthalpy as ∆H = H products – H