[urtula]

Hallo all,


I know that the pH is influenced by the temperature of the mixture.
But why?

Is it safe to say that the (only) reason for this is that the temperature will influence the equilibrium in the mixture.
By this I mean: endothermic reaction will be favoured and the exothermic one will not be favoured and thus you change the equilibrium and thus the pH.

Or is this not a correct, complete answer?

[18uos]

with the increase in temperature the dissociation of ions of an elctrolyte increases so that's  y pH changes,but as far the reaction thermodynamic is concerned ,that reaction will be favored which maintains the equilibrium,according to Le chatelier's principle.
but as the heat is absorbed by the system in endothermic reaction so this reaction will be favored in forward direction i.e to increase the no. of ions in the solution.
quote author=urtula link=topic=34336.msg131580#msg131580 date=1246467590]
Hallo all,


I know that the pH is influenced by the temperature of the mixture.
But why?

Is it safe to say that the (only) reason for this is that the temperature will influence the equilibrium in the mixture.
By this I mean: endothermic reaction will be favoured and the exothermic one will not be favoured and thus you change the equilibrium and thus the pH.

Or is this not a correct, complete answer?


[/quote]

[Phlogiston]

Hallo all,


I know that the pH is influenced by the temperature of the mixture.
But why?

Is it safe to say that the (only) reason for this is that the temperature will influence the equilibrium in the mixture.
By this I mean: endothermic reaction will be favoured and the exothermic one will not be favoured and thus you change the equilibrium and thus the pH.

Or is this not a correct, complete answer?

No, you're correct.  Qualitatively that's the essential part- since the autoionization reaction of water is endothermic, a higher temperature will favor products, i.e. more H⁺ will be produced and hence the pH will drop.