. A 38.1 mL sample of a 0.391 M aqueous hydrocyanic acid solution is titrated with a 0.475 M aqueous sodium hydroxide solution. What is the pH after 13.1 mL of base have been added? 1b. Determine the pH change when 0.117 mol NaOH is added to 1.00 L of a buffer solution that is 0.393 M in HF and 0.224 M in F-. pH after addition − pH before addition = pH change =

You want to make a buffer with a pH of 10.00 from NH4+/NH3. (a) What must the [ NH4+ ]/[ NH3 ]ratio be? (b) How many moles of NH4Cl must be added to 465 mL of an aqueous solution of 1.24 M NH3 to give this pH? (c) How many milliliters of 0.236 M NH3 must be added to 2.08 g of NH4Cl to give this pH? (d) What volume of 0.499 M NH3 must be added to 395 mL, of 0.109 M NH4Cl to give this pH?

Consider the titration of HF (K a=6.7104) with NaOH. What is the pH when a third of the acid has been neutralized?

An aqueous solution of 0.057 M weak acid, HX, has a pH of 4.65. What is the pH of the solution if 0.018 mol of KX is dissolved in one liter of the weak acid?

Enough water is added to the buffer in Question 29 to make the total volume 10.0 L. Calculate (a) the pH of the buffer. (b) the pH of the buffer after the addition of 0.0500 mol of HCl to 0.600 L of diluted buffer. (c) the pH of the buffer after the addition of 0.0500 mol of NaOH to 0.600 L of diluted buffer. (d) Compare your answers to Question 29(a)-(c) with your answers to (a)-(c) in this problem. (e) Comment on the effect of dilution on the pH of a buffer and on its buffer capacity.

Consider the nanoscale-level representations for Question 110 of the titration of the aqueous weak acid HX with aqueous NaOH, the titrant. Water molecules and Na+ ions are omitted for clarity. Which diagram corresponds to the situation: After a very small volume of titrant has been added to the initial HX solution? When enough titrant has been added to take the solution just past the equivalence point? Halfway to the equivalence point? At the equivalence point? Nanoscale representations for Question 110.

A buffer solution was prepared by adding 4.95 g sodium acetate to 250. mL of 0.150-M acetic acid. What ions and molecules are present in the solution? List them in order of decreasing concentration. Calculate the pH of the buffer solution. Calculate the pH of 100. mL of the buffer solution if you add 80. mg NaOH. (Assume negligible change in volume.) Write a net ionic equation for the reaction that occurs to change the pH.

A buffer is made up of 239 mL of 0.187 M potassium hydrogen tartrate (KHC4H4O6) and 137 mL of 0.288 M potassium tartrate (K2C4H4O6). Ka for is (H2C4H4O6)4.55105. Assuming volumes are additive, calculate (a) the pH of the buffer. (b) the pH of the buffer after adding 0.0250 mol of HCI to 0.376 L of the buffer. (c) the pH of the buffer after adding 0.0250 mol of KOH to 0.376 L of the buffer.

What is meant by the capacity of a buffer? Describe a buffer with low capacity and the same buffer with greater capacity.

A buffer solution that is 0.100 M acetate ion and 0.100 M acetic acid is prepared. (a) Calculate the initial pH, final pH, and change in pH when 1.00 mL of 1.00 M NaOH is added to 100.0 mL of the buffer. (b) Calculate the initial pH, final pH, and change in pH when 1.00 mL of 1.00 M NaOH is added to 100.0 mL pure (pH 7.00) water.