Titration of Strong Monoprotic Acid and Base
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Transcript of Titration of Strong Monoprotic Acid and Base
Titration of Strong Monoprotic Acid and Base
Polyprotic Acids
How to solve Ka expression for Polyprotic Acids?
Polyprotic Acids/Bases
Bethany Storro
• polyprotic acid can donate more than one proton• polyprotic base can accept more than one proton
H2SO4Ba(OH)2
Equilibrium Expressions for Polyprotics
• Ka1 = ionization constant for the first hydrogen atom
H2S(aq) + H2O(l) H3O+(aq) + HS-(aq)
• Ka2 = ionization constant for the second hydrogen atom
HS-(aq) + H2O(l) H3O+(aq) + S2-
(aq)
Ka1 compared to Ka2
• If the difference between the Ka1 and the Ka2 values is 103 or more, the pH generally depends only on the first dissociation.
• Unique among common acids• STRONG in is first dissociation step ( ≥1.0 M)• WEAK acid in the second step (use quadratic)
H2SO4
Typical Titration with Weak Monoprotic Acids
Do the Structure, Initial Concentration of A/B influence pH ?
• Investigate your designated question• Design a series of investigations involving
titrations• Analyze titration curves• Pool data/Compare data with others• Answer primary question of lab
Available Materials• 0.2 M HCl• 0.1 M H2SO4
• 0.05 M HNO3
• 0.1 M HC2H3O2
• 0.2 M NH3
• 0.1 M NaOH• 0.1 M Ca(OH)2
• Stir rod• 2 x 100 mL grad. cylinders• 2 x 250 flasks
• Ring • pH strips, probe• 2 x 50 mL burets + clamp