Heats Effect on Borax
By: Alexis H. Prince
Department of Chemistry; Coastal Carolina University, Conway, SC 29526
April 13, 2015
Borax has many uses, whether it’s being used as an antiseptic, helping to cure people, getting rid of pests, or even assisting fruit trees in their growth. It is actually the most important source of the element boron, and has been used for years as a “water softening agent.” Borax was found forming in saline lakes, or one may find it in Boron, California. Historically, “the first Borax specimens came from several dry lake deposits in Tibet” (The Mineral Borax). This experiment was conducted to determine the standard entropy and enthalpy of the dissolving reaction of borax in water. The…show more content… This was put on a low setting so the temperature of the borax solution would heat up by 5-7°C. Once the solution maintained a stable temperature, the steps taken earlier were repeated for a total of 5 times.
Results and Discussion Upon completing the experiment, the standard entropy was found to be 334.82 Joules/mol with an 11.9% error in comparison to the literature value, and the standard enthalpy was 108.82 kilojoule/mol with a 1.07% error in comparison to its literature value. Since both of the results found were positive, it confirmed the class’s earlier hypothesis of it being an endothermic reaction. In addition, the value of Gibbs free energy was calculated (see Figure 1). Since both entropy and enthalpy were positive, the spontaneity of the solution was temperature dependent. This experiment showed to have a non-spontaneous reaction, due to the heat that was applied to the system in order for the borax to dissociate into an aqueous solution.
Looking at the R2 value on Figure 2, one will notice how relatively small the number is, as well as how close to one the value is. This number indicates how close or precise the experimental results are. Also shown in this table are solubility products or Ksp, which is the equilibrium constant for a solid dissolving in water. Solubility products do change with temperature, so it is important to always note the temperature at which the solubility is measured because more of the borax solid is dissolving. When titrating