Download 5 - Polyprotic Acids

SCH4U – Acid Base Chemistry
493712450
Date: ________________________
Polyprotic Acids
Acids that contain ________________________ active proton
When polyprotic acids dissociate, they donate ____________________ at a time
The second proton dissociation is much ______________ and therefore usually only
consider the ___________________________
Generally, we only consider the ______ dissociation when calculating [H3O+] and pH
Subsequent dissociations will be ________________ by hydronium _____________
from the first dissociation
Example: H3PO4
Ka1 = 7.52x10-3
Ka2 = 6.23x10-8
Ka3 = 2.2 x 10-13
Calculate the pH of 3.5 M H3PO4. Then calculate the [H2PO4-] and [HPO42-].
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SCH4U – Acid Base Chemistry
493712450
Example:
Adipic acid is a diprotic acid used to manufacture nylon. Its formula can be
shortened to H2Ad. The acid dissociation constants for adipic acid are
K a1  3.71 10 5 and K a2  3.87  10 6 . What is the pH of a 0.085 mol/L solution of
adipic acid?
Mixtures of Acids
When dealing with a mixture of two acids, it is usually only necessary to consider the
_______________________
The dissociation suppresses dissociation of _______________________
Example
Calculate the pH of a solution of 1.00 M HCN and 5.00 M HClO2.
KHCN = 6.2x10-10
KHClO2 = 1.1x10-2
Homework
Page 578
Question 14
Page 579
Questions 1, 4, 17, 20
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