The first step, that of breaking down the solid crystal, is endothermic while the second step, that of hydrating the individual particles released into the solvent, is exothermic. For an ionic compound, ionic bonds are broken while ion-dipole forces are formed. Ion-dipole forces are formed when the slightly positive hydrogen atoms are attracted to the negative ions, and the slightly negative oxygen atoms are attracted to the positive ions. The overall heat of solution depends on the relative amounts of energy involved in the two individual steps. Hydration of ions.
Hydration involves a complex redirection of forces of attraction and repulsion.
In this experiment, you will determine the heats of solution for the dissolving of ammonium nitrate and of sodium acetate in water, using a simple styrofoam cup as a calorimeter. To relate the heat of solution involved to the two-step process of dissolving. Find the data table included with this lab and familiarize yourself with its layout. Accurately find the mass of a sample of solid ammonium nitrate of approximately 15 grams. Find the mass of the pair of dry styrofoam cups.