What ratio of NaCN to HCN is needed to prepare a pH 9.90 buffer? (Ka of HCN is 4.9 × 10⁻¹⁰)

Calculate the pH change when 10.0 mL of 0.100-M NaOH is added to 90.0 mL pure water, and compare the pH change with that when the same amount of NaOH solution is added to 90.0 mL of a buffer consisting of 1.00-M NH3 and 1.00-M NH4Cl. Assume that the volumes are additive. Kb of NH3 = 1.8 × 10-5.

Which of the acid-base indicators discussed in this chapter would be suitable for the titration of (a) HNO3 with KOH. (b) KOH with acetic acid. (c) HCl with NH3. (d) KOH with HNO2. Explain your answers.

A buffer is prepared by mixing 525 mL of 0.50 M formic acid, HCHO2, and 475 mL of 0.50 M sodium formate, NaCHO2. Calculate the pH. What would be the pH of 85 mL of the buffer to which 8.6 mL of 0.15 M hydrochloric acid had been added?

Sketch a titration curve for the titration of potassium hydroxide with HCl, both 0.100 M. Identify three regions in which a particular chemical species or system dominates the acid-base equilibria.

How many grams of NaF must be added to 70.00 mL of 0.150 M HNO3 to obtain a buffer with a pH of 4.68?

Ammonia gas is bubbled into 275 mL of water to make an aqueous solution of ammonia. To prepare a buffer with a pH of 9.56, 15.0 g of NH4Cl are added. How many liters of NH3; at 25C and 0.981 atm should be used to prepare the buffer? Assume no volume changes and ignore the vapor pressure of water.

Which of the following would form a buffer if added to 250.0 mL of 0.150 M SnF2? (a) 0.100 mol of HCl (b) 0.060 mol of HCI (c) 0.040 mol of HCl (d) 0.040 mol of NaOH (e) 0.040 mol of HF

A buffer is prepared by dissolving 0.0250 mol of sodium nitrite, NaNO2, in 250.0 mL of 0.0410 M nitrous acid, HNO2. Assume no volume change after HNO2 is dissolved. Calculate the pH of this buffer.

A good buffer generally contains relatively equal concentrations of weak acid and conjugate base. If you wanted to buffer a solution at pH = 4.00 or pH = 10.00, how would you decide which weak acidconjugate base or weak baseconjugate acid pair to use? The second characteristic of a good buffer is good buffering capacity. What is the capacity of a buffer? How do the following buffers differ in capacity? How do they differ in pH? 0.01 M acetic acid/0.01 M sodium acetate 0.1 M acetic acid/0.1 M sodium acetate 1.0 M acetic acid/1.0 M sodium acetate