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so the added NaOH will react with the acetic acid to form more CH3COO-, making a strong base into a weaker base. Adding HCl will cause it to react with CH3COO- to form more CH3COOH, making a strong acid a weak acid. Both acids and bases will be neutralized since the buffer has both a weak acid and a conjugate base. Experimental Outline:1) Make 150 mL of approx. 0.1 M NaOH from 5.0 M NaOH and standardize it against KHP using 0.2 g KHP and 25 mL of water over 3 trials. 2) Make 150 mL of approximately 0.1 M acetic acid from 6.0 M acetic acid using 10.0 mL of acetic acid and titrate it against 10.06 mL of the standardized NaOH. 3) Calculate the concentration of the acetic acid. 4) Determine the pKa of acetic acid by measuring the pH of acetic acid. 5) Make a buffer solution that has an equal concentration of both acetic acid and sodium acetate. 6) Determine the pKa of acetic acid from the buffer solution and compare the pKa values obtained from the 2 methods. 7) Test the buffer solutions by adding approximately 0.1 M of NaOH and 0.1 M of HCL to separate samples of saltwater and buffer. 8) Measure initial and final pH of the buffer and saltwater after HCl and NaOH have been added.
Chemical Hazards and Wastes:Make sure to wear goggles, lab coat, and gloves at all times in the lab. Handle acids with care since they can burn the skin. Properly dispose of all wastes in its proper waste containers. Conclusion:The initial known pKa value of acetic acid is 4.75, and the measured was 4.76. We cannot comment on its accuracy because there is no accepted value of the molarity of sodium hydroxide. The second method that was used to figure out pKa proved to be more efficient and faster than the first method. The data was also somewhat precise since the RSD value was calculated to be approximately 1.7146. Lastly, our hypothesis was proven where the pH of the buffer slightly changed when the base and acid was introduced, but changed dramatically when it was added to saltwater.