Chapter 17: Additional Aspects of Aqueous Equilibria

Name ______Date ______Period ___

Homework

Chapter 17: Additional Aspects of Aqueous Equilibria

Exercises: Sections 17.3: Acid-Base Titrations

1. Define the following terms:

a) titration:

b) standard solution:

c) equivalence point:

d) end point:

e) pH titration curve:

d) titrant

2. How does titration of a strong, monoprotic acid with a strong base differ from titration of a weak,

monoprotic acid with a strong base with respect to the following:

(a) quantity of base required to reach the equivalence point;

(b) pH at the beginning of the titration;

2. Continued:

(d) pH after addition of a slight excess of base;

(e) choice of indicator for determining the equivalence point?

3. Assume that 30.0 mL of a 0.10 M solution of a weak base "B" that accepts one proton is titrated with a

0.10 M solution of the monoprotic strong acid HX.

(a) How many moles of HX have been added at the equivalence point?

(b) What is the predominant form of B at the equivalence point? ______

(d) Which indicator, phenolphthalein or methyl red is likely to be the better choice for this titration?

Explain.

4. How many milliliters of 0.105 M HCl are needed to titrate each of the following solutions to the

equivalence point:

(a) 35.0 mL of 0.0950 M NaOH;

i) calculate moles of NaOH present

ii) calculate the volume of HCL needed

(b) 40.7 mL of 0.117 M KOH;

i) calculate moles of KOH present

ii) calculate the volume of HCL needed

5. A 30.0-mL sample of 0.200 M KOH is titrated with 0.150 M HClO4 solution.

(a) In the space below, write i) the complete chemical equation for this reaction and ii) the net ionic

equation for this reaction.

(b) Calculate moles of OH – in the original 30.0-mL sample of KOH

(d) Calculate the pH after the following volumes of acid have been added:

5. Continued:

(II) 39.5 mL

(III) 39.9 mL

5. Continued:

IV) 40.0 mL;

(V) 40.1 mL.

6. Consider the titration of 30.0 mL of 0.100 M NH3 with 0.150 M HCl.

(a) Write the complete chemical equation for this reaction.

(b) Write the equilibrium equation and then look up the Kb value for the reaction of NH3 with water.

(d) Calculate the pH after the following volumes of titrant have been added:

(I) 0 mL

6. Continued

(II) 10.0 mL

6. Continued:

(III) 19.5 mL

6. Continued:

(IV) 20.0 mL

6. Continued:

v) 20.5 mL

(vi) 30.0 mL