ThermochemistryHard
Question
The enthalpy of neutralization of a weak monoprotic acid (HA) in 1M solution with a strong base is -55.95 kJ/mol. If the unionized acid requires 1.4 kJ/mol heat for it's complete ionization and enthalpy of neutralization of the strong monobasic acid with a strong monoacidic base is -57.3 kJ/mol. What is the % ionization of the weak acid in molar solution ?
Options
A.1%
B.3.57%
C.35.7%
D.10%
Solution
HA → H+ + A- ; áƒrH = 1.4 kJ/mol
áƒHneutralization = + áƒrH of (H+ + OH- H2O)
- 55.95 = - 57.3
for 1 M HA = 1.35 kJ/mol
% heat utilized by 1 M acid for ionization
= 
× 100 = 96.43%
So, acid is 100 - 96.43 = 3.57% ionized.
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