1.

Question

Calculate the pH of a buffer solution that contains 0.32 M benzoic acid (C6H5CO2H) and 0.17 M sodium benzoate (C6H5COONa). [Ka = 6.5 × 10-5 for benzoic acid] Round your answer to two places past the decimal.

2.
A solution is prepared by mixing 470 mL of 0.18 M Tris·Base and 598 mL of 0.27 M Tris·Acid. What is the pH of this solution? [Ka(Tris·Acid) = 8.5 × 10-9] Round your answer to two places past the decimal.

3.
Calculate the pH of a buffer solution prepared by dissolving 0.21 mole of 3-chloropropanoic acid, HC3H4O2Cl and 0.86 mole of sodium 3-chloropropanoate, NaC3H4O2Cl in enough water to make 0.79 liter of solution. [Ka(HC3H4O2Cl) = 7.8 × 10-5] Round your answer to two places past the decimal.

4.
You are asked to go into the lab and prepare an acetic acid-sodium acetate buffer solution with a pH of 5.08 ± 0.02. What molar ratio of CH3COONa (conjugate base) to CH3COOH (weak acid) should be used? Read carefully. Round your answer to two places past the decimal.

5.
A buffer is prepared by adding 0.91 L of 0.99 M HCl to 815 mL of 1.5 M NaHCOO. What is the pH of this buffer? [Ka(HCOOH) = 1.7 × 10-4] Round your answer to two places past the decimal.

6.
A certain monoprotic weak acid with Ka = 0.44 can be used in various industrial processes. (a) What is the [H+] for a 0.202 M aqueous solution of this acid and (b) what is its pH? Round the [H+] to three significant figures and the pH to two places past the decimal and do NOT use scientific notation.

7.
What is the pH of 65 mL of a 1.3 M benzoic acid (HC7H5O2, Ka=6.4x10–5) solution after 20 mL of a 0.33 NaOH solution is added? Round your answer to two places past the decimal.

Answer 1

Why don't I do the first one and laeve the others for you. All of these are buffer problems using the Henderson-Hasselbalch equation.
1.
pH = pKa + log(base)/(acid)
pH = 6.5E-5 + log(0.17)/(0.32)= ?

4. It's the RATIO you want so solve for (base)/(acid)