Abstract The experiment, Chemical Equilibrium in Solution, makes use of a titration of a heterogeneous solution. This is done in order to find the distribution of molecular Iodine, I2, as the solute between two immiscible liquid phases, water and a hexane solution. The average values obtained for (I2) = 6.11E-06 M, (I-) = 0.1097, (I3-) = 2.82E-04. The results that were found in this experiment show an inaccuracy. This may have been due to the third run in…show more content… Distribution constant is not a true thermodynamic equilibrium constant. This is determined by titration of both phases with the standard thiosulfate solution when I2 is distributed between hexanes and pure water.
II. Experimental Method
The experimental method was similar to the experiment that is described in the textbook (Experiments in Physical Chemistry, 7th ed., Exp. 12). The experiment was modified as follows: Instead of using carbon tetrachloride, hexanes were used instead. This is due to hexanes not being as harmful to use and similar results can be obtained. The first thing that was accomplished was to measure the distribution constant, k, defined by
k = (I2)w (2)
The iodine is represented in two phases. The hexanes is represented by , h, and the aqueous phase is represented by, w, in Eq. 2. The quantities for each run is given in Table 1 (runs 1 to 3). The values used for this calculation is found in the results section in Table 6. Each run is a different Molarity of I2 to check the variation of the distribution constant with the concentration. The Erlenmeyer flasks that contained the solutions were equilibrated at 25˚C, after shaken for 5 minutes. The flasks were yet again shaken for 5 more minutes, after being in the thermostat bath for 10 minutes, and yet placed again in the bath for another 10 minutes. This is to allow the liquids to separate out completely. The flasks,