What characteristics of phenolphthalein made it appropriate to use for tritration? is there a way to do experiments without it? how does phenolphtahalein 's endpoint relate to the equivalence point of the reaction?

The characteristics of phenolphthalein that makes it appropiate for use for tritation is that phenolphthalein is colourless in acidic media but pink in basic solutions.

That means that in the equivalence point (well, just a tiny amount of the solution being added after reaching the equivalence point) the colour of the solution being tritraed will change.

If the solution being triated is an acid, it will remain colourless with the phenolphtalein, and it will turn pink at the equivalence point.

You can do experiments without phenolphthalein if you use a different indicator of pH (substances that change of color when pass from acid to basic or from basic to acid). Some other indicators of pH are methyl red, bromothymol blue and thymol blue. There are others.

High-energy and unstable.