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18 Nov 2019
Make a buffer mixture containing 2 mL of the acid component and 20 mL of the solution containing the conjugate base. Mix, and measure the pH. Calculate a third value for pK_a. To that solution add 3 mL 0.10 M NaOH. Measure the pH Explain your results. Add 30 mL water to your buffer mixture, mix, and pour half of the resulting solution into another 100-mL beaker Measure the pH of the diluted buffer. Calculate pK. once again. Add five drops of 0.10 M NaOH to the diluted buffer and measure the pH again. To the other half of the diluted buffer add 5 drops 0.10 M HCI, and again measure the pH. Record your results. On the lab bench, we have 0.10 M stock solutions that can be used to make three different common buffer systems. These are HC_2H_3O_2^- C_2H_3O_2 acetic acid-acetate ion NH_4^+ - NH_3 ammonium ion-ammonia HCO_3 - CO_3^2- hydrogen carbonate-carbonate Using a graduated cylinder measure out 15 mL of the acid component of your buffer into a 100-ml. beaker. the acid will be one of the following solutions: 0.10 M HC_2H_3O_2,0, 10 M NH_4Cl, or 0.10 M NaHCO_3 Rinse out the graduated cylinder with distilled water and use it to add 15 mL of the conjugate base of your buffer. Measure the pH of your mixture and record it on the Data page. Calculate pK for the acid.
Make a buffer mixture containing 2 mL of the acid component and 20 mL of the solution containing the conjugate base. Mix, and measure the pH. Calculate a third value for pK_a. To that solution add 3 mL 0.10 M NaOH. Measure the pH Explain your results. Add 30 mL water to your buffer mixture, mix, and pour half of the resulting solution into another 100-mL beaker Measure the pH of the diluted buffer. Calculate pK. once again. Add five drops of 0.10 M NaOH to the diluted buffer and measure the pH again. To the other half of the diluted buffer add 5 drops 0.10 M HCI, and again measure the pH. Record your results. On the lab bench, we have 0.10 M stock solutions that can be used to make three different common buffer systems. These are HC_2H_3O_2^- C_2H_3O_2 acetic acid-acetate ion NH_4^+ - NH_3 ammonium ion-ammonia HCO_3 - CO_3^2- hydrogen carbonate-carbonate Using a graduated cylinder measure out 15 mL of the acid component of your buffer into a 100-ml. beaker. the acid will be one of the following solutions: 0.10 M HC_2H_3O_2,0, 10 M NH_4Cl, or 0.10 M NaHCO_3 Rinse out the graduated cylinder with distilled water and use it to add 15 mL of the conjugate base of your buffer. Measure the pH of your mixture and record it on the Data page. Calculate pK for the acid.