Acids Lesson 20 Titration Curves

Titration Curves  A titration curve is a graph of the pH changes that occur during an acid-base titration versus the volume of acid or base added. There are three types of titration curves. You need to be able to recognize each and then choose a suitable indicator for that titration.   The equivalence point is the end of a titration where the stoichiometry of the reaction is exactly satisfied, or moles H+ = moles OH-. The transition point refers to when an indicator changes color and [HInd] = [Ind-].

Choosing an Indicator When you choose an indicator, you must pick one so that the transition point of the indicator matches the equivalence point of the titration. When acid base titration is at the equivalence point, the acid has neutralized the base leaving only a salt and water. The pH of the equivalence point depends on type of salt.   Rule of thumb If the salt is neutral the equivalence point = 7 If the salt is basic the equivalence point = 9 If the salt is acidic the equivalence point = 5

1. Titration Curve: Strong Acid and Strong Base   HCl + KOH →

1. Titration Curve: Strong Acid and Strong Base   HCl + KOH → KCl + HOH

1. Titration Curve: Strong Acid and Strong Base HCl + KOH → KCl + HOH Indicator

1. Titration Curve: Strong Acid and Strong Base   HCl + KOH → KCl + HOH Indicator pH = 7 Bromothymol Blue

1. Titration Curve: Strong Acid and Strong Base   HCl + KOH → KCl + HOH Indicator pH = 7 Bromothymol Blue 50 mL of 0.10 M KOH is added to 25 mL of 0.10 M HCl

1. Titration Curve: Strong Acid and Strong Base HCl + KOH → KCl + HOH   HCl + KOH → KCl + HOH Indicator pH = 7 Bromothymol Blue 50 mL of 0.10 M KOH is added to 25 mL of 0.10 M HCl pH Volume .10 M KOH added 14 7 25 50

1. Titration Curve: Strong Acid and Strong Base HCl + KOH → KCl + HOH   HCl + KOH → KCl + HOH Indicator pH = 7 Bromothymol Blue 50 mL of 0.10 M KOH is added to 25 mL of 0.10 M HCl pH Volume .10 M KOH added 14 7 0.10 M HCl 25 50

1. Titration Curve: Strong Acid and Strong Base HCl + KOH → KCl + HOH   HCl + KOH → KCl + HOH Indicator pH = 7 Bromothymol Blue 50 mL of 0.10 M KOH is added to 25 mL of 0.10 M HCl pH Volume .10 M KOH added 14 7 0.10 M HCl Neutral Salt 25 50

1. Titration Curve: Strong Acid and Strong Base HCl + KOH → KCl + HOH   HCl + KOH → KCl + HOH Indicator pH = 7 Bromothymol Blue 50 mL of 0.10 M KOH is added to 25 mL of 0.10 M HCl pH Volume .10 M KOH added 14 7 0.10 M KOH 0.10 M HCl Neutral Salt 25 50

1. Titration Curve: Strong Acid and Strong Base HCl + KOH → KCl + HOH   HCl + KOH → KCl + HOH Indicator pH = 7 Bromothymol Blue 50 mL of 0.10 M KOH is added to 25 mL of 0.10 M HCl pH Volume .10 M KOH added 14 7 25 50

1. Titration Curve: Strong Acid and Strong Base HCl + KOH → KCl + HOH   HCl + KOH → KCl + HOH Indicator pH = 7 Bromothymol Blue 50 mL of 0.10 M KOH is added to 25 mL of 0.10 M HCl pH Volume .10 M KOH added 14 7 25 50

2. Titration Curve: Weak Acid and Strong Base   HCN + KOH →

2. Titration Curve: Weak Acid and Strong Base   HCN + KOH → KCN + HOH

2. Titration Curve: Weak Acid and Strong Base HCN + KOH → KCN + HOH Indicator

2. Titration Curve: Weak Acid and Strong Base HCN + KOH → KCN + HOH Indicator pH = 9 Phenolphthalein

2. Titration Curve: Weak Acid and Strong Base HCN + KOH → KCN + HOH Indicator pH = 9 Phenolphthalein 20 mL of 1.0 M HCN is added to 10 mL of 1.0 M KOH

2. Titration Curve: Weak Acid and Strong Base HCN + KOH → KCN + HOH Indicator pH = 9 Phenolphthalein 20 mL of 1.0 M HCN is added to 10 mL of 1.0 M KOH pH Volume 1.0 M HCN added 14 7 10 20

2. Titration Curve: Weak Acid and Strong Base HCN + KOH → KCN + HOH Indicator pH = 9 Phenolphthalein 20 mL of 1.0 M HCN is added to 10 mL of 1.0 M KOH pH Volume 1.0 M HCN added 14 7 1.0 M KOH 10 20

2. Titration Curve: Weak Acid and Strong Base HCN + KOH → KCN + HOH Indicator pH = 9 Phenolphthalein 20 mL of 1.0 M HCN is added to 10 mL of 1.0 M KOH pH Volume 1.0 M HCN added 14 7 1.0 M KOH Basic Salt 10 20

2. Titration Curve: Weak Acid and Strong Base HCN + KOH → KCN + HOH Indicator pH = 9 Phenolphthalein 20 mL of 1.0 M HCN is added to 10 mL of 1.0 M KOH pH Volume 1.0 M HCN added 14 7 1.0 M KOH Basic Salt 1.0 M HCN 10 20

2. Titration Curve: Weak Acid and Strong Base HCN + KOH → KCN + HOH Indicator pH = 9 Phenolphthalein 20 mL of 1.0 M HCN is added to 10 mL of 1.0 M KOH pH Volume 1.0 M HCN added 14 7 1.0 M KOH Basic Salt 1.0 M HCN 10 20

2. Titration Curve: Weak Acid and Strong Base HCN + KOH → KCN + HOH Indicator pH = 9 Phenolphthalein 20 mL of 1.0 M HCN is added to 10 mL of 1.0 M KOH pH Volume 1.0 M HCN added 14 7 10 20

2. Titration Curve: Weak Acid and Strong Base HCN + KOH → KCN + HOH Indicator pH = 9 Phenolphthalein 20 mL of 1.0 M HCN is added to 10 mL of 1.0 M KOH Buffer Zone pH Volume 1.0 M HCN added 14 7 10 20

2. Titration Curve: Weak Acid and Strong Base HCN + KOH → KCN + HOH Indicator pH = 9 Phenolphthalein 20 mL of 1.0 M HCN is added to 10 mL of 1.0 M KOH Buffer Zone Weak Acid & Salt are present pH Volume 1.0 M HCN added 14 7 10 20

3. Titration Curve: Strong Acid and Weak Base   HCl + NH3 →

3. Titration Curve: Strong Acid and Weak Base   HCl + NH3 → NH4+ + Cl-

3. Titration Curve: Strong Acid and Weak Base   HCl + NH3 → NH4+ + Cl- Indicator

3. Titration Curve: Strong Acid and Weak Base   HCl + NH3 → NH4+ + Cl- Indicator pH = 5 Methyl Red

3. Titration Curve: Strong Acid and Weak Base   HCl + NH3 → NH4+ + Cl- Indicator pH = 5 Methyl Red 60 mL of 1.0 M NH3 is added to 30 mL of 1.0 M HCl

3. Titration Curve: Strong Acid and Weak Base HCl + NH3 → NH4+ + Cl-   HCl + NH3 → NH4+ + Cl- Indicator pH = 5 Methyl Red 60 mL of 1.0 M NH3 is added to 30 mL of 1.0 M HCl pH Volume 1.0 M NH3 added 14 7 30 60

3. Titration Curve: Strong Acid and Weak Base HCl + NH3 → NH4+ + Cl-   HCl + NH3 → NH4+ + Cl- Indicator pH = 5 Methyl Red 60 mL of 1.0 M NH3 is added to 30 mL of 1.0 M HCl pH Volume 1.0 M NH3 added 14 7 1.0 M HCl 30 60

3. Titration Curve: Strong Acid and Weak Base HCl + NH3 → NH4+ + Cl-   HCl + NH3 → NH4+ + Cl- Indicator pH = 5 Methyl Red 60 mL of 1.0 M NH3 is added to 30 mL of 1.0 M HCl pH Volume 1.0 M NH3 added 14 7 1.0 M HCl Acid Salt 30 60

3. Titration Curve: Strong Acid and Weak Base HCl + NH3 → NH4+ + Cl-   HCl + NH3 → NH4+ + Cl- Indicator pH = 5 Methyl Red 60 mL of 1.0 M NH3 is added to 30 mL of 1.0 M HCl pH Volume 1.0 M NH3 added 14 7 1.0 M NH3 1.0 M HCl Acid Salt 30 60

3. Titration Curve: Strong Acid and Weak Base HCl + NH3 → NH4+ + Cl-   HCl + NH3 → NH4+ + Cl- Indicator pH = 5 Methyl Red 60 mL of 1.0 M NH3 is added to 30 mL of 1.0 M HCl pH Volume 1.0 M NH3 added 14 7 30 60 1.0 M NH3 1.0 M HCl Acid Salt

3. Titration Curve: Strong Acid and Weak Base HCl + NH3 → NH4+ + Cl-   HCl + NH3 → NH4+ + Cl- Indicator pH = 5 Methyl Red 60 mL of 1.0 M NH3 is added to 30 mL of 1.0 M HCl pH Volume 1.0 M NH3 added 14 7 30 60

3. Titration Curve: Strong Acid and Weak Base HCl + NH3 → NH4+ + Cl-   HCl + NH3 → NH4+ + Cl- Indicator pH = 5 Methyl Red 60 mL of 1.0 M NH3 is added to 30 mL of 1.0 M HCl pH Volume 1.0 M NH3 added 14 7 Buffer Zone Weak Base & Salt are present 30 60

4. Match the Curve with the Reaction pH Volume .10 M KOH added 14 7 25 50 A. 3HCl + Al(OH)3 → AlCl3 + 3HOH B. HCl + KOH → KCl + HOH C. HCN + KOH → KCN + HOH

4. Match the Curve with the Reaction pH Volume .10 M KOH added 14 7 25 50 Bisect the verticle pH = 7 A. 3HCl + Al(OH)3 → AlCl3 + 3HOH B. HCl + KOH → KCl + HOH C. HCN + KOH → KCN + HOH

4. Match the Curve with the Reaction pH Volume .10 M KOH added 14 7 25 50 Bisect the verticle pH = 7 A. 3HCl + Al(OH)3 → AlCl3 + 3HOH B. HCl + KOH → KCl + HOH C. HCN + KOH → KCN + HOH

5. Match the Curve with the Reaction pH Volume 1.0 M NH3 added 14 7 30 60 A. 3HCl + Al(OH)3 → AlCl3 + 3HOH B. HCl + KOH → KCl + HOH C. HCN + KOH → KCN + HOH

5. Match the Curve with the Reaction pH Volume 1.0 M NH3 added 14 7 Bisect the verticle pH = 5 30 60 A. 3HCl + Al(OH)3 → AlCl3 + 3HOH B. HCl + KOH → KCl + HOH C. HCN + KOH → KCN + HOH

6. Match the Curve with the Reaction pH Volume 1.0 M NH3 added 14 7 30 60 A. 3HCl + Al(OH)3 → AlCl3 + 3HOH B. HCl + KOH → KCl + HOH C. HCN + KOH → KCN + HOH

6. Match the Curve with the Reaction pH Volume 1.0 M NH3 added 14 7 Bisect the verticle pH = 9 30 60 A. 3HCl + Al(OH)2 → AlCl3 + 3HOH B. HCl + KOH → KCl + HOH C. HCN + KOH → KCN + HOH

6. Match the Curve with the Reaction pH Volume 1.0 M NH3 added 14 7 Bisect the verticle pH = 9 30 60 A. 3HCl + Al(OH)2 → AlCl3 + 3HOH B. HCl + KOH → KCl + HOH C. HCN + KOH → KCN + HOH