Bromocresol Green Equilibrium System Post-Lab Discussion This experiment was conducted to determine whether the equilibrium constant is consistent at a constant temperature. The answer was found by comparing mixtures of a bromocresol green equilibrium system at different concentrations. A spectrophotometer and a pH electrode provided the means to ultimately determine the concentration of HIn, H+, and In-. From these values, we were able to calculate the equilibrium constant (K). The data supports the hypothesis. The calculated values for K for samples 1-5, respectively, are as follows: 2.48 x 10^4, 4.27 x 10^4, 4.25 x 10^4, 4.27 x 10^4, and 4.31 x 10^4. The mean for this data set is 3.92 x 10^4. Each standard deviation is 0.80 x 10^4. The range of two standard deviations from the mean correlates to approximately 2.34 x 10^4 to 5.49 x 10^4. Therefore, all calculated values of K for samples 1-5 fell within two standard deviations of the mean and it is safe to accept the hypothesis that the equilibrium constant is truly constant. …show more content…
The equilibrium constant is calculated by dividing the product of [H+] and [In-] by [HIn]. Changing the pH of the solution affects the value of [H+] and thus the value of the equilibrium constant. A higher pH yields a higher K. A lower pH yields a lower