What is the effect of temperature and concentration on acid disociation constant?

1 Answer
anor277
Jun 4, 2018

Well, equilibrium constants are generally INDEPENDENT of concentration...

Explanation:

...however, we would expect that for weak acids, #HX#, whose protonolysis reaction we would represent as the equilibrium ...

#HX(aq)+H_2O(l)rightleftharpoonsH_3O^+ + X^-#

Now this is a BOND-BREAKING reaction...i.e. we break the #H-X# bond....and we expect that if we supply heat, we should drive the equilibrium to the right. And so let us look at some data..

#2H_2O(l) rightleftharpoonsH_3O^+ + HO^-# #K_a=10^-14# at #298*K#...

According to this site #pK_a=6.63# at #50# #""^@C#, and #pK_a=6.14# at #100# #""^@C#. Perhaps you could work out values for #K_a# at each temperature. Are these data in accord with our prediction? Why or why not?

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