Ch.16 - Aqueous Equilibrium WorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Titration Curves

Titration curves help us to understand the neutralization occurring between an acid and base in order to identify the equivalence point. 

Equivalence Point

The equivalence point is when the moles of acid and base titrating are equal in amount. 

Concept #1: Understanding an Acid–Base Titration Curve.

In a typical titration we begin with an acid or base and slowly add either a Strong Acid or Strong Base. 

Concept #2: The Equivalence Point. 

Depending on the types of acids and bases mixing, at the equivalence point, the pH can be less than, greater than or equal to 7. 

Example #1: The following questions refer to the titration curve given below.

1) The titration curve shows the titration of

    a) a strong acid with a strong base    b) a weak acid with a strong base    c) a strong base with a strong acid    d) a weak base with a strong acid      

2) Which point on the titration curve represents a region where a buffer solution has formed?

     a) point A      b) point B      c) point C      d) point D

3) Which point on the titration curve represents the equivalence point? 

    a) point A      b) point B      c) point C      d) point D

4) Which of the following would be the best indicator to use in the titration?

    a) erythrosin B, pKa=2.9    b) methyl blue, pKa=5.4    c) bromthymol blue, pKa= 6.8    d) o-cresonphthalein, pKa=9.0   

An indicator represents a weak acid or base in low concentration that changes color in an acid base titration. An indicator shows us the location of our endpoint, which is located near our equivalence point. 

Example #2:  The acid form of an indicator is red and its anion is blue. The Ka value for this indicator is 10 -9. What will be the approximate pH range over which this indicator changes color?
a) 3-5        b) 4-6        c) 5-7        d) 8-10        e) 9-11

An indicator, like a buffer, has an optimal range in which it works most effectively:

pka +/- 1. 

Practice: What will be the color of the indicator in the above question in a solution that has a pH of 6?

Example #3: Consider the titration of 100.0 mL of 0.016 M H2SO4 with 0.400 M NaOH at the equivalence point. How many many milliliters of 0.400 M NaOH are required to reach the equivalence point?

If at the equivalence point, the moles of acid equal the moles of base and moles equal molarity multiplied by liters then at the equivalence point we can use the formula: 

Example #4: Consider the titration of 40.0 mL of 0.0800 M HCl with 0.0160 M Ca(NH2)2.

a) How many milliliters of 0.0160 M Ca(NH2)2 are required to reach the equivalence point? 

When dealing with the equivalence point make sure you correctly calculate the molarity for both the acid and base. 

Example #5: Consider the titration of 40.0 mL of 0.0800 M HCl with 0.0160 M Ca(NH2)2.

b) What is the pH of this solution?

Practice: Consider the titration of 60.0 mL of 0.200 M H3PO3 solution with 0.350 M potassium hydroxide, KOH solution. How many milliliters of base would be required to reach each of its equivalence points? 

Additional Problems
Which of the following is the most reasonable estimate of the value of the pH at the equivalence point of a titration of a hydrofluoric acid with a strong base? A)  14.0    B)  7.0    C)  5.5    D)  1.0    E)  8.5  
When an acid solution is titrated with a standard base solution, separate burets are sometimes used for each solution. Which mistake would necessitate emptying and refilling burets, and starting the titration over? (A) overshooting the endpoint (B) starting with less acid than called for by the procedure (C) adding distilled water to the titration flask after a solution was measured into it from the buret (D) allowing drops of distilled water to stay in the burets while filling them
Examine the titration curves. Which statement is FALSE?A. Curve (i) shows the titration of 50.0 mL of 0.15 M HCl with 0.15 M NaOH.B. Curve (ii) shows the titration of 50.0 mL of 0.15 M NH 4Cl with 0.15 M NaOH.C. Curve (iii) shows the titration of 50.0 mL of 0.15 M CH 3COOH with 0.15 M NaOH.D. Curve (iv) shows the titration of 50.0 mL of 0.15 M H 3PO4 with 0.15 M NaOH.
a. At what volume of added base is the pH calculated by working an equilibrium problem based on the initial concentration and Ka of the weak acid?b. At what volume of added base does pH = p Ka?c. At what volume of added base is the pH calculated by working an equilibrium problem based on the concentration and Kb of the conjugate base?
Which of the following curve best represents the titration of Na 2CO3 with HCl? 
Define the end point of a titration. a. It is a synonym for equivalence point. b. It is the point at which the pH no longer changes. c. It is when a change that indicates equivalence is observed in the analyte solution.
Identify the equivalence point on the titration curve shown here.a. A is the equivalence pointb. D is the equivalence pointc. C is the equivalence pointd. B is the equivalence point
Below is the pH curve for a titration of a weak base with 0.10 M HCl. What is the p  Kb of the weak base? 1. 9.42. 2.73. 4.64. 7.00
Consider the titration curve given below. This titration curve corresponds to the titration of a ....(a) weak base (flask) with a strong acid (buret).(b) strong base (flask) with a strong acid (buret).(c) weak acid (flask) with a strong base (buret).(d) strong acid (flask) with a strong base (buret).
A student titrates an unknown monoprotic acid with NaOH solution from a buret. After the addition of 12.35 mL of NaOH, the pH of the solution is 5.22. The equivalence volume is 24.70 mL. What is the Ka of the acid?
Which titration curve could describe the titration of a solution of HCl by addition of a solution of KOH?
Identify each type of titration curve as involving a strong or weak acid or base. What is the significance of the half-equivalence point? Identify this point on the relevant curves below.
Suppose you titrated 50mL of a 1.0 M monoprotic acid solution with a 2.0 M NaOH solution. If the Ka of your acid is 1.0 x 10-6, which of the following curves best represents the titration?
The following questions refer to the titration curve given below.  For each of the following questions circle the correct answer.           a) The titration curve shows the titration of  i. a strong acid with a strong base                             ii. a weak acid  with a strong base        iii. a strong base  with a strong acid                          iv. a weak base with a strong acid                                 b) Which point on the titration curve represents a region where a buffer solution has formed?            point A                          point B                          point C                          point Dc) Which point on the titration curve represents the equivalence point?            point A                          point B                          point C                          point Dd) Which of the following would be the best indicator to use in the titration?     i. erythrosin B  pKa = 2.9                      ii. methyl red pK   a = 5.4                                                iii. bromthymol blue pKa = 6.8             iv. o-cresonphthalein pK  a = 9.0 
The titration curve shown below represents a 25 mL aqueous solution that is titrated with another solution at the same molarity. Which of the following statement is TRUE regarding the titration?A. The curve could represent the titration of NaOH with HCl (adding HCl to NaOH)B. The equivalence point is at pH 7C. Point A is in the buffer regionD. At point C, there is excess base presentE. The curve could represent the titration of H2SO4 with NaOH (adding NaOH to H2SO4)
The graph below displays data from what type of titration curve? Weak acid titrated with weak baseA) Weak acid titrated with strong baseB) Strong base titrated with weak acidC) Weak base titrated with strong acidD) Strong acid titrated with strong base
Below is the pH curve for a titration of a weak base with 0.10 M HCl. What is the pKb of the weak base?1. 9.42. 2.73. 8.74. 7.005. 4.6 6. 5.37. 11.3
The curve for the titration of 50.0 mL of 0.0200 M HClO(aq) with 0.100 M NaOH(aq) is given below. Estimate the pKa of HClO.a) 7.0b) 10.0c) 12.0d) 5.0e) 7.5
Which titration curve could describe the titration of a solution of HCl by addition of a solution KOH? 
Which titration curve could describe the titration of a solution of NH2OH by addition of a solution of HNO3?  
A titration of 25 mL of a monoprotic acid solution with a 0.1M NaOH solution yielded the following titration curve:a. What was initial molar concentration of the acid? ___________________b. What is the Ka of the acid? ___________________
Identify the equivalence point on the titration curve shown here.a. A is the equivalence pointb. D is the equivalence pointc. C is the equivalence pointd. B is the equivalence point 
On the weak base/strong acid titration curve below, label the following points.a) The point where the pH corresponds to a solution of the weak base (B) in water.b) The point where the pH corresponds to a solution of the conjugate acid (BH +) in water.c) The point where pH=pKa (for BH+).