pH of water at 24°c is 7. What effect does increase in temperature results in pH of water?
1)pH will be more than 7
2) pH will be less than 7
3) pH will be equal to 7
4) can't be determined
Option 2 is correct ans .
Dissociation of water is an endothermic reversible reaction.
When temperature is increased , for an endothermic reaction in equilibrium , it shifts the equilibrium to forward direction i.e. more product is formed which in this case means : more water is dissociated ( more H+ concentration ) is obtained . Ph= negative logarithm of H+ concentration so, more H+ concentration means, lesser Ph. so , whole ph range gets changed when temperature is increased i.e at that time, our neutral point is lesser than 7 but, still water is neutral !