The Solubility of Potassium Bitartrate.docx

Title: The Solubility of Potassium Bitartrate Abstract: The solution used in this experiment was solution #6. It was found that the total concentration of K+ decreases as the amount of KCl used decreases. It was also found that many of the Ksp calculations were relatively the same, however, there were some discrepancies among the groups. Lastly it was also found that the [HC4HO6-] was the same as the solubility and that it increased as the amount of KCl used decreased. Introduction: The goal of this experiment was to see how the solubility of potassium bitartrate in water was affected by the presence of other ions in the solution. The method used in the experiment was the titration of a saturated solution of Potassium Bitartrate to the endpoint with NaOH. The equation for this titration is as follows: HC4H4O6- + OH- -> H2O + C4H4O62- Experimental: One gram of KHC4H4O6 was measured into a 100ml Beaker and the appropriate volume of KCl and NaCl was added to the solid. This solution was then stirred for 20 minuets. After this it was filtered into a beaker, 20mL of the sample was then added to an Erlenmeyer flask. 25mL of water and 3 drops of phenolphthalein indicator were added. Then the solution was titrated to the endpoint using .0495M NaOH. Results and Discussion: Tables of Results B. Graphs C. Answers to Questions: The trends seen in the data are as the total concentration of K+ decreases the amount of KCl used decreases. It was also found that many of the Ksp calculations were relatively the same, however, there were some discrepancies among the groups. Lastly it was also found that the [HC4HO6-] was the same as the solubility and that it increased as the amount of KCl used decreased. D. Discussion of Errors: Some possible sources or error in this experiment include blowing out the pipettes. This would have increased the amount of sample used and would have required more NaOH to titrate it to the endpoint. This in turn would have increased the average concentration of Bitartrate and thrown off the Ksp. Another error that could have occurred would be assuming that the filtering of the potassium bitartrate completely removed all the undissolved potassium bitartrate and only left us with a saturated solution of potassium bitartrate. Which again would have affected the Ksp because it would have taken more NaOH to titrate it to the endpoint. Lastly, all of this data is based on values taken at 25C which might not necessarily have been true, this would have altered the Ksp because the solubility might have increased or decreased with a difference in temperature. Solution Number Solubility [HC4H4O6-] [K+] Total Ksp 1A 5.32x10^-3 5.32x10^-3 0.106 5.5x10^-4 1B 4.89x10^-3 4.89x10^-3 0.105 5.13x10^-4 2A 6.24x10^-3 6.24x10^-3 0.087 5.40x10^-4 2B 5.82x10^-3 5.82x10^-3 0.086 5.00x10^-4 3A 6.36x10^-3 6.36x10^-3 0.066 4.22x10^-4 3B 6.99x10^-3 6.99x10^-3 0.067 4.68x10^-4 4A 4.81x10^-3 4.81x10^-3 0.0448 2.15x10^-4 4B 4.18x10^-3 4.18x10^-3 0.0442 1.85x10^-5 5A 1.53x10^-2 1.53x10^-2 0.0353 5.40x10^-4 5B 1.57x10^-2 1.57x10^-2 0.0357 5.60x10^-4 6A 3.50x10^-2 3.50x10^-2 0.035 1.23x10^-3 6B 3.72x10^-2 3.72x10^-2 0.0372 1.38x10^-3