Question

(6 points) 95. A student is given three different acetic acid/acetate (HC2H302/C2H302) buffers: Buffer 1: HC2H302/C2H302* has a ratio of (1:1) Buffer 2: HC2H202/C2H302" has a ratio of ( 1:10) Buffer 3: HC2H302/C2H302 has a ratio of 1:100) Buffer 4: HC2H302/C2H302has a ratio of ( 1:1000) In two experiments, a student is asked to measure the pH of these Buffers (1 through 4) (20.0 mL each) followed by these experiments. Experiment I: The student adds 2 drops of 1M HCl to each of the 20.0 mL buffer solution (Buffers 1 through 4) and then measures the pH of these solutions after the addition of the HCI. Experiment II: The student adds 2 drops of 1M NaOH to each of the 20.0 mL buffer solution (Buffers 1 through 4) and then measures the pH of these solutions after the addition of the NaOH. The results from these experiments are shown below. Buffer 1 (1:1) pH Buffer 2 Buffer 3 (1:10) (1:100) pH Грн 5.977.00 Buffer 4 (1:1000) pH, 7.82 pH Before the addition of HCI pH After the addition of HCI 4.84. 5.87 6.60 6.82 PH Before the addition of NaOH 4.84 7.00 7.82 pH After the addition of NaOH 4.84 7.50 10.82

Answer 1

Dale Choo and choom are present. Mence, it is acidic buffer when Hill is added, it reacts with Choo CH coo & He ? cucoom & cé So, moles of CH Cod will decrease and moles of Chycoon will increase on reaction with the pH = pka t log (cry coo") [cycwon] un pH will decrease on addition When Nooh is added, it reacts with Cty COOH of the Chcoon & Naon ? cu coo Nat & HO So, moles of ch cool will decreace and motes of CH₂ Cos will increase on reaction with Naom — БИ — i u іnсхеоце In Buffer ratio of chloo school is lil Hence, buffer capacity is maximum as pH = pka Therefore, no effect on addition of 2 drops of the or Naoh. In all other buffers (2, 3, 4) pH decrease on addition of nice and ph increase on addition of Naoh..