# The values can be used to form a linear equation

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in linear form y = mx+b, and the determination of K of the reaction at each temperature. The values can be used to form a linear equation where ln K sp = y and x = 1/T. The determinations of ln K sp and 1/T were calculated when performing the titration with HCl at different temperatures and the van Hoff plot with ln K sp = y and 1/T = x as described above refer to figure 1. Using the graph the values of the unknown can then be solved for, the slope of the line is used to determine the change in enthalpy and the y-intercept is the change in entropy, refer to figure 1. The experimental values of ∆H and ∆S are -1376.5J and 3.83J/k respectively, refer to figure 1 and calculations. These determinations are not very accurate because some of the groups titration values were not within 1% making the measurements not very precise with the van Hoff plot having a R 2 value of 0.3018, this number is nowhere close to one, refer to figure 1 and table 1 and table 2.
By using, a fully saturated solution of aqueous borax and titrating with 0.2500M HCl and using bromocresol green as the indicator the point in which the tetraborate ion was fully titrated. The titration was performed at six different temperatures to find different equilibrium constants at each temperature, plotting these points on a graph then finding the linear trend-line of y = -11444x + 31.8. this gives the values for ∆H° and ∆S°, because -11444 = ∆H°/R and 31.8= ∆S°/R refer to figure 1. The borax reaction has to be endothermic because the solubility increases as the temperature increases forcing the reaction to shift increasingly to the right as the temperature increases. The higher the temperature, the more borax will dissolve in the water. The K sp at 22°C was 0.0016 M 3 . The K sp for 25°C was 0.0045 M 3 , the K sp for 30°C was 0.0025 M 3 , the K sp for 35°C 0.0021M 3 , the K sp for 40°C 0.076M 3 , and the K sp for 45°C was 0.074M 3 , refer to table one and two. Even though the data from the experiment is not very precise, the values were still going up with higher temperature.