Chap19Notes - Chem 1036 Chapter 19 1 of 50 Chem 1036 Chapter 19 3 of 50 How does a buffer work Example HC2H3O2 C2H3O2 There is an equilibrium between

# Chap19Notes - Chem 1036 Chapter 19 1 of 50 Chem 1036...

This preview shows page 1 - 3 out of 13 pages. Chem 1036 Chapter 19 5 of 50 Chem 1036 Chapter 19 6 of 50 Buffer Calculations Example Problem : What is the pH of a buffer that is composed of 0.25 M HC 2 H 3 O 2 and 0.35 M NaC 2 H 3 O 2 ? K a = 1.8 x 10 –5 . HC 2 H 3 O 2 ( aq ) + H 2 O( l ) H 3 O + ( aq ) + C 2 H 3 O 2 ( aq ) Initial: 0.25 M 0 0.35 M Change:______________________________________________ Equilibrium: K a = 1.8 x 10 –5 = > @ + 3 2 3 2 2 3 2 H O C H O HC H O ± ª º ª º ¬ ¼ ¬ ¼ = Chem 1036 Chapter 19 7 of 50 Henderson-Hasselbalch Equation for buffers : HA( aq ) + H 2 O( l ) H 3 O + ( aq ) + A ( aq ) K a = > @ 3 H O A HA ² ± ª º ª º ¬ ¼ ¬ ¼ (p K a = –log[ K a ]) a [base] pH p log [acid] K ² Chem 1036 Chapter 19 8 of 50 Example Problem : What is the pH of a buffer that is composed of 0.25 M HC 2 H 3 O 2 and 0.35 M NaC 2 H 3 O 2 ? K a = 1.8 x 10 –5 .  #### You've reached the end of your free preview.

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