What is the pH of a solution prpared by mixing 50.0 ml of .200 M HCLO4 with 10.0 ml of .100 M KOH

Answer 1

HClO4 + KOH ==> KClO4 + H2O
moles HClO4 = M x L = ?
moles KOH = M x L = ?

The reagent with the larger number of moles will be the one remaining. That reagent will be M = moles/total L soln and convert to pH from there.