The objectives of this experiment are to determine:
a) the heat capacity of a calorimeter
b) the heat of fusion of ice
c) the heat of neutralization
d) the enthalpy of hydration of magnesium sulfate
Note: as explained in the section of the Zumdahl text covering "Enthalpy," for reactions at constant pressure, the terms “heat of reaction” and “change in enthalpy” are used interchangeably.
In this experiment, you will use a calorimeter, an apparatus used for measuring the amount of heat evolved or absorbed during a chemical reaction or physical transformation, to study three different reactions. The calorimeter you use will have its own heat capacity, the ability of an object to hold heat, which will figure into to the calculations for the various heats of reaction you are trying to determine. Therefore, Part A of this experiment will require you to determine heat capacity of your specific calorimeter based on the change in temperature when a known amount of heat is added to the calorimeter containing a known amount of water. As you perform the reactions in Parts B-D in the calorimeter, you will use the observed change in temperature with the heat capacity of the calorimeter to calculate the change in enthalpy for each reaction.
In Part B, you will determine the energy required to convert H2O (s) to H2O (l) (specifically for the phase change). Part C will focus on determining the heat released by an exothermic reaction, specifically the neutralization of acid by NaOH. Finally, in Part C, you will determine the enthalpy needed to hydrate magnesium sulfate, making magnesium sulfate heptahydrate.