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Set up a 50 ml buret and fill it with the

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Set up a 50 mL buret and fill it with the standardized HCl solution. You will need to obtain enough HCl solution, and have it standing by at your bench, to fill the buret twice. Expel the air bubbles from the buret, take an initial volume reading, and titrate the borax sample until the blue color disappears and the sample turns yellow. This is the endpoint of a bromocresol green titration. Take a final volume reading and immediately begin preparing the next sample to be titrated. You may wish to use the final volume of one titration as the initial volume of the next, and you can--provided more acid has not been added to the buret. A full buret (50 mL) of acid should be sufficient to titrate the full temperature range of one of the two sets of samples. Repeat this titration procedure until at least one set of borax samples, covering the complete temperature range, has been titrated. If time permits, you should do all ten to get the best possible data set, and to be able to 'selectively edit' from your data any "bad" samples or mistakes. The remaining borax mixture, and all titration samples, can be flushed down the drain with running water. Please carefully rinse your buret before returning it. Allow the hotplate to cool before returning it to the cabinet.
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Data Handling and Analysis Use the data of initial and final HCl volumes, and molarity of HCl, to calculate number of moles of borax in each titrated sample. Calculate values for the solubility product constant (K sp ) for borax at the various temperatures. Remember to convert your temperature values to Kelvin for purposes of finding thermodynamic quantities. Plot ln K sp vs. 1/T for all ten samples. Determine H (kJ/mol) and S (J/mol K) from this graph. Calculate the values for G for each sample using: 1). Equation (A) 2). Equation (B) , with your solved values for H and S as found earlier. Note that you'll assume that H and S are constant over this temperature range. Are they? Plot G vs. T for both methods of finding temperature-dependent free energy change values.
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Data Tables -- Simultaneous Determination of Several Thermodynamic Quantities Molarity of Standardized HCl __________ Room Temperature, °C __________ Room Temperature, K __________ Solution Temperature Trial #1 Trial #2 Volume of Borax Solution __________ __________ Final Volume, HCl __________ __________ Initial Volume, HCl __________ __________ Total Volume, HCl __________ __________ Moles HCl __________ __________ Moles Borax __________ __________ Concentration of Borax in sample __________ __________ Solubility Product, K sp __________ __________ Average K sp __________ Free Energy Change, G __________ __________ Graphically Determined Values Change in Enthalpy, H __________ Change in Enthalpy, S __________ Table of Temperature, Equilibrium Constant, and Free Energy Change Values Temperature (°C) Temperature (K) Free Energy Change ( G) Equilibrium Constant ( K ) 40 35 30 25 Room (_____)
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