pH

[moni]

A sample of 25.0ml of 0.10 M lactic acid (HC3H5)3 , pKa =3.850 is titrated with 0.10 NaOH aquation solution. What is the volume of the base needed to reach equivalence point?what is the Ph at the equivalance point? help please!!!!!!!!!

[Borek]

Once you will sove the formic acid question this one will be a breeze

Besides, these calculations are descibed in the pH cheat sheet, you just have to understand what you have to calculate.

[RobJim]

Volume of acid solution => moles of acid => moles of base => volume of base is the process for the first part. The second part requires some equation; can't remember off the top of my head. Henderson-Hasselbach?

[Deronius]

Just use some bromthymol blue as a Ph indicator.

[rctrackstar2007]

Use the indicator to know when you've reached the equivalence point. The use: pH=pKa + log([H+]/[HA](undisociated acid))

I believe that is how you do it.

[Borek]

Originally Posted by RobJim

The second part requires some equation; can't remember off the top of my head. Henderson-Hasselbach?

No, HH can be used before equivalence point. At equivalence you have just a solution of sodium lactate - salt of weak acid and strong base, so you calculate pH from lactate hydrolyzis.

Check titration curve calculation lecture.