![Page 1: Chemistry 40S Unit 5: Acids & Bases Lesson 4. Learning Outcomes C12-5-08: Write the equilibrium expression (K a or K b ) from a balanced chemical equation](https://reader038.vdocument.in/reader038/viewer/2022103123/56649dba5503460f94aab24e/html5/thumbnails/1.jpg)
Chemistry 40SUnit 5: Acids & BasesLesson 4
![Page 2: Chemistry 40S Unit 5: Acids & Bases Lesson 4. Learning Outcomes C12-5-08: Write the equilibrium expression (K a or K b ) from a balanced chemical equation](https://reader038.vdocument.in/reader038/viewer/2022103123/56649dba5503460f94aab24e/html5/thumbnails/2.jpg)
Learning Outcomes C12-5-08: Write the equilibrium
expression (Ka or Kb) from a balanced chemical equation.
C12-5-09: Use Ka or Kb to solve problems for pH, percent dissociation, and concentration.
![Page 3: Chemistry 40S Unit 5: Acids & Bases Lesson 4. Learning Outcomes C12-5-08: Write the equilibrium expression (K a or K b ) from a balanced chemical equation](https://reader038.vdocument.in/reader038/viewer/2022103123/56649dba5503460f94aab24e/html5/thumbnails/3.jpg)
Acid Dissociation Constant (Ka)
Strong acids completely dissociate do not establish equilibrium
Weak acids do not completely dissociate do establish equilibrium E.g. HA + H2O ⇌ H3O+ + A–
Can write an equilibrium law for weak acids
![Page 4: Chemistry 40S Unit 5: Acids & Bases Lesson 4. Learning Outcomes C12-5-08: Write the equilibrium expression (K a or K b ) from a balanced chemical equation](https://reader038.vdocument.in/reader038/viewer/2022103123/56649dba5503460f94aab24e/html5/thumbnails/4.jpg)
Acid Dissociation Constant (Ka)
HA + H2O ⇌ H3O+ + A–
Just like with Keq the value of Ka indicates the state of equilibrium The larger the Ka = the larger the [P]
stronger acid & more dissociation
![Page 5: Chemistry 40S Unit 5: Acids & Bases Lesson 4. Learning Outcomes C12-5-08: Write the equilibrium expression (K a or K b ) from a balanced chemical equation](https://reader038.vdocument.in/reader038/viewer/2022103123/56649dba5503460f94aab24e/html5/thumbnails/5.jpg)
Base Dissociation Constant Base Dissociation Constant (Kb)
reflects the strength of the base and its ability to dissociate
Everything works the same as with Ka…
![Page 6: Chemistry 40S Unit 5: Acids & Bases Lesson 4. Learning Outcomes C12-5-08: Write the equilibrium expression (K a or K b ) from a balanced chemical equation](https://reader038.vdocument.in/reader038/viewer/2022103123/56649dba5503460f94aab24e/html5/thumbnails/6.jpg)
Dissociation Constant ProblemsExample 1: A 0.10 mol/L solution of acetic acid is only partly ionized. If at equilibrium, the hydronium ion concentration is 1.3×10–3 mol/L, what is the acid dissociation constant, Ka?
![Page 7: Chemistry 40S Unit 5: Acids & Bases Lesson 4. Learning Outcomes C12-5-08: Write the equilibrium expression (K a or K b ) from a balanced chemical equation](https://reader038.vdocument.in/reader038/viewer/2022103123/56649dba5503460f94aab24e/html5/thumbnails/7.jpg)
Dissociation Constant ProblemsExample 2: HA is a weak acid with a Ka of 7.3×10–8. What is the concentration of all species (HA, H3O+ and A–) if the initial concentration of HA is 0.50 mol/L?
![Page 8: Chemistry 40S Unit 5: Acids & Bases Lesson 4. Learning Outcomes C12-5-08: Write the equilibrium expression (K a or K b ) from a balanced chemical equation](https://reader038.vdocument.in/reader038/viewer/2022103123/56649dba5503460f94aab24e/html5/thumbnails/8.jpg)
Percent Dissociation Several ways to describe acids and
bases: Concentration Strong or weak Degree of dissociation
Can also be described by percent dissociation:
x 100%
![Page 9: Chemistry 40S Unit 5: Acids & Bases Lesson 4. Learning Outcomes C12-5-08: Write the equilibrium expression (K a or K b ) from a balanced chemical equation](https://reader038.vdocument.in/reader038/viewer/2022103123/56649dba5503460f94aab24e/html5/thumbnails/9.jpg)
Percent Dissociation x 100% x 100%
![Page 10: Chemistry 40S Unit 5: Acids & Bases Lesson 4. Learning Outcomes C12-5-08: Write the equilibrium expression (K a or K b ) from a balanced chemical equation](https://reader038.vdocument.in/reader038/viewer/2022103123/56649dba5503460f94aab24e/html5/thumbnails/10.jpg)
Percent Dissociation ProblemsExample 3: Calculate the percent dissociation of a 0.100 mol/L solution of formic acid (HCH2O2) if the hydronium ion concentration is 4.21×10–4 mol/L.
![Page 11: Chemistry 40S Unit 5: Acids & Bases Lesson 4. Learning Outcomes C12-5-08: Write the equilibrium expression (K a or K b ) from a balanced chemical equation](https://reader038.vdocument.in/reader038/viewer/2022103123/56649dba5503460f94aab24e/html5/thumbnails/11.jpg)
Percent Dissociation ProblemsExample 4: Calculate the Kb of the hydrogen phosphate ion (HPO4
2–) if a 0.25 mol/L solution of sodium hydrogen phosphate is dissociated is 0.080%.
![Page 12: Chemistry 40S Unit 5: Acids & Bases Lesson 4. Learning Outcomes C12-5-08: Write the equilibrium expression (K a or K b ) from a balanced chemical equation](https://reader038.vdocument.in/reader038/viewer/2022103123/56649dba5503460f94aab24e/html5/thumbnails/12.jpg)
pH, pOH, Ka & Kb ProblemsExample 5: What is the pH of a 0.10 mol/L solution of the imaginary acid, HA, if its Ka is 4.0×10–9.
![Page 13: Chemistry 40S Unit 5: Acids & Bases Lesson 4. Learning Outcomes C12-5-08: Write the equilibrium expression (K a or K b ) from a balanced chemical equation](https://reader038.vdocument.in/reader038/viewer/2022103123/56649dba5503460f94aab24e/html5/thumbnails/13.jpg)
pH, pOH, Ka & Kb ProblemsExample 6: The pH of a 0.20 mol/L solution of CO3
2– ions, is 10.75. What is the Kb of carbonate ions?