Question

I am completing a lab where I had to determine the mass percent of Mg(OH)2 in an antacid tablet , and I am trying to determine sources of error for my lab. I was wondering if when I back-titrated with NaOH after I overshot on purpose would the added OH- ions form extra Mg(OH)2 precipitate instead of neutralizing the H+ ions?

Answer 1

If you over shot the end point in which you are titrating HCl with NaOH, there is no H^+ to neutralize at the equivalence point of the titration. So some extra Mg(OH)2 COULD form but if you over shot on purpose, why would that cause a problem. If I over shot the end point, I would simply back titrate with HCl to get back to the equivalence point.