dxtxpx
Forum Guru
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The ionization of acetic acid is described by the following simple equation
HA = H+ plus A-
When pH of a solution of acetic acid is equal to the pK, the ratio of anion concentration to the following un-ionized acid concentration [A-]/[HA] is
a) 0
b) 1
c) 1.5
d) 2.0
e) 2.5
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| peekay
Forum Guru
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Posts: 588
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may be ratio is 2.0. I did more guessing littel logic
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| dxtxpx
Forum Guru
Topics: 259
Posts: 1,233
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correct answer is choice b) 1.0
The equilibrium constant for ionization of a weak acid such as acetic acid is described by the equation
k=[H+] [A-]/ [HA]
the Henderson-Hasselbalch equation is
pH=pk + log 10 [A-]/ [HA]
It describes the relationship between pH and pK. When pH is equal to pK, the log 10 [A-]/[HA] is 0 , i.e., [A-]/[HA]=1
pH is defined as -log10[H+]. A 0.01 M solution of acetic acid would be essentialy completely ionized. Therefore [H+] would be 0.01 M= 10-2 M. Therefore pH would be equal to 2.0
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