Which of the following would be best for a buffer with a pH of 7.5? a. HF/F- b. H3PO4/H2PO4- c. H2PO4-/HPO4^2- D. HCN/CN-

Which of the following  constitute a buffer? A. NH3 and KNO3 B. HCN & NaCN C. HF & NaCl D. NaOH & NaCl Group of answer choices C A & C B A, B and C

At which point in the titration curve below is a buffer present? C Volume titrant added (mL) A. Ο Ρoint A В. О Рoint B C. O Point C D. O Point D E. OA buffer is not present at any point during this titration.

Which is the best acid to use in the preparation of a buffer with pH = 9.8? A. HNO3 HOI (Ką = 2.0 × 10-11) O C. HIO3 (Ka = 1.7 × 10-1) D. HNO2 (Ka = 4.5 × 10-4) B.

Which of the following best describes Buffers?   A. Buffers are weak acid and conjugate base pairs that resist changes in the pH of a solution. B. Buffers promote pH changes of a solution by contributing hydronium ions to the solution. C. Buffers are solutions containing a strong acid and a weak base resulting in neutralization. D. Buffers are of minimal importance to pH regulation in body fluids.

Calculate the pH of a titration of 50.00 mL of 0.100 M Phenylacetic acid, Ka = 4.9 x 10-5, with 0.100 M NaOH at the following points: a. Before any NaOH is added.      b. After 18.7 mL of NaOH are added.   c. After 25.00 mL of NaOH are added.   d. After 50.00 mL of NaOH are added.   e. After 53.00 mL of NaOH are added.   C) What is the pKa of the acid (show calculation)? please solve sub-parts a,b, and c.

13

For each of the buffer systems below, determine the concentration of the acid and base components in the buffer: 1) An acetate buffer with a pH of 5.15 and a concentration of 3.5M. The (HC2H302] = Type your answer here M and the [NAC2H302] = Type your answer here M 2) A Carbonate buffer with a pH of 9.85 and a concentration of 0.50M. The [NAHCO3] = Type your answer here M and the Na2CO3] = Type your answer here M 3) A Phosphate buffer of pH 2.5 and a concentration of 1.0M. The [H3PO4] = Type your answer here Mand the [KH2PO4) Type your answer here

P5

What conjugate base could be used to make a phosphoric acid (H3PO4) buffer at pH = 2? a. H2PO4^- b. H3PO4 c. HPO4^2- d. PO4^3-