لخّصلي

Every chemical change is accompanied by a change in energy, usually in the form of heat.In this experiment, you will calculate the enthalpy change of the above displacement reaction by adding an excess of zinc powder to a measured amount of CuSO4 (aq) and measuring the temperature change over a period of time.This quantity of heat is measured experimentally by allowing the reaction to take place in a thermally insulated vessel called calorimeter.?T [1]

 The heat capacity of the system represents the amount of heat required to raise the temperature of the system 1oC, and ?T is the difference between the final and initial temperatures: ?T = Tf -  Ti.The energy change of a reaction that occurs at constant pressure is termed the heat of reaction or the enthalpy change.If the calorimeter were perfect, no heat would be radiated to the laboratory. 0).

Every chemical change is accompanied by a change in energy, usually in the form of heat. The energy change of a reaction that occurs at constant pressure is termed the heat of reaction or the enthalpy change. The symbol ΔH is used to denote the enthalpy change. If heat is evolved, the reaction is exothermic (ΔH  0); and if heat is absorbed, the reaction is endothermic (ΔH  0). In this experiment, you will calculate the enthalpy change of the above displacement reaction by adding an excess of zinc powder to a measured amount of CuSO4 (aq) and measuring the temperature change over a period of time.
This quantity of heat is measured experimentally by allowing the reaction to take place in a thermally insulated vessel called calorimeter. The heat liberated in the reaction will cause an increase in the temperature of the solution and of the calorimeter. If the calorimeter were perfect, no heat would be radiated to the laboratory. The calorimeter you will use in this experiment is shown in Figure 3.1.
Because we are concerned with the heat of the reaction and because some heat is absorbed by the calorimeter itself, we must know the amount of heat absorbed by the calorimeter. In this experiment, the temperature of the calorimeter and its contents is measured before and after the reaction. The change in enthalpy, ΔH, is equal to the negative product of the heat capacity of the calorimeter and its content times the temperature change, ΔT,:

 ΔH = –  (heat capacity of the calorimeter + heat capacity of content)  ΔT     [1]



 The heat capacity of the system represents the amount of heat required to raise the temperature of the system 1oC, and ΔT is the difference between the final and initial temperatures: ΔT = Tf –  Ti.