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

Jun 4, 2018

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

#### Explanation:

...however, we would expect that for weak acids, $H X$, whose protonolysis reaction we would represent as the equilibrium ...

$H X \left(a q\right) + {H}_{2} O \left(l\right) r i g h t \le f t h a r p \infty n s {H}_{3} {O}^{+} + {X}^{-}$

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..

$2 {H}_{2} O \left(l\right) r i g h t \le f t h a r p \infty n s {H}_{3} {O}^{+} + H {O}^{-}$ ${K}_{a} = {10}^{-} 14$ at $298 \cdot K$...

According to this site $p {K}_{a} = 6.63$ at $50$ ""^@C, and $p {K}_{a} = 6.14$ 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?