Titration curves help

Hi, I just need someone to clear up what the difference or connection is between the pKin to the equivalence point.

My understanding is that the pKin means the end point in which the acid and alkali are in equal concentrations.

The equivancle point is when they have fully reacted together. so when would you use both the pKin and the equivalence point together.

First of all you must be aware that indicators are themselves weak acids.

The mid point of the indicator is when the pH = pKa of the indicator.

the indicator is chosen so that this coincides with the large inflexion that occurs at the mid point of the titration. It does not have to be exactly the same as the pH of a titration changes by several pH units with the addition of 1 drop of acid or base at the end point.

For example phenolphthalein has a pKa of 9.7 and so is suitable for weak acid - strong base titrations when the pH may change from 5 to 10 with one drop.

What I dont understand is the equivalence point in which, is when the acid and base have fully reacted. So does this mean the equivalence point is always going to be at pH 7.

The equivalence point is when there is an equivalent amount of H+ and OH- and this would be the end point of a titration. Does this mean the solution is pH 7? No because the salt may react with the water and form an acidic or alkaline solution.If you neutralised HCl with NH3 at the equivalence point there will be NH4Cl and H2O but NH4+ ions are proton donors and are therefore acidic so at the equivalence point of this titration the pH will be less than pH 7.
If a weak acid is used eg CH3COOH against a strong base like NaOH then at the equivalence point only CH3COONa and H2O remain but the CH3COO- ion can accept H+ ions from water leaving OH- and so the solution has a pH of more than 7.