You are given the following acidbase titration data, where each point on the graph represents the pH after adding a given volume of titrant (the substance being added during the titration). a What substance is being titrated, a strong acid, strong base, weak acid, or weak base? b What is the pH at the equivalence point of the tiration? c What indicator might you use to perform this titration? Explain.

a Draw a pH titration curve that represents the titration of 50.0 mL of 0.10 M NH3 by the addition of 0.10 M HCl from a buret. Label the axes and put a scale on each axis. Show where the equivalence point and the buffer region are on the titration curve. You should do calculations for the 0%, 30%, 50%, and 100% titration points. b Is the solution neutral, acidic, or basic at the equivalence point? Why?

What is an acidbase indicator? Define the equivalence (stoichiometric) point and the end point of a titration. Why should you choose an indicator so that the two points coincide? Do the pH values of the two points have to be within 0.01 pH unit of each other? Explain.

A bottle of concentrated hydroiodic acid is 57% HI by weight and has a density of 1.70 g/mL. A solution of this strong and corrosive acid is made by adding exactly 10.0 mL to some water and diluting to 250.0 mL. If the information on the label is correct, what volume of 0.988 M NaOH is needed to neutralize the HI solution? Suggest an indicator for the titration.

A student intends to titrate a solution of a weak monoprotic acid with a sodium hydroxide solution but reverses the two solutions and places the weak acid solution in the buret. After 23.75 mL of the weak acid solution has been added to 50.0 mL of the 0.100 M NaOH solution, the pH of the resulting solution is 10.50. Calculate the original concentration of the solution of weak acid.

Identify each pair that could form a buffer. (a) NaOH and NaCl (b) NaOH and NH3 (c) Na3PO4 and Na2HPO4

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.

A solution of weak base is titrated to the equivalence point with a strong acid. Which one of the following statements is most likely to be correct? a The pH of the solution at the equivalence point is 7.0. b The pH of the solution is greater than 13.0. c The pH of the solution is less than 2.0. d The pH of the solution is between 2.0 and 7.0. e The pH of the solution is between 7.0 and 13.0. The reason that best supports my choosing the answer above is a Whenever a solution is titrated with a strong acid, the solution will be very acidic. b Because the solution contains a weak base and the acid (titrant) is used up at the equivalence point, the solution will be basic. c Because the solution contains the conjugate acid of the weak base at the equivalence point, the solution will be acidic.

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.