Posted by chips ahoy on .
The pH of saturated is found to be 13.12. A 15.0mL sample of saturated Sr(OH)2 is diluted to 250.0mL in a volumetric flask. A 15.0 mL sample of the diluted Sr(OH)2 is transferred to a beaker, and some water is added. The resulting solution requires 27.6mL of a HCl solution for its titration.What is the molarity of this HCl solution?
Sr(OH)2 ==> Sr^+2 + 2OH^-
pH = 13.12
pH + pOH = pKw = 14 and
pOH = 0.88; therefore, (OH^-) = 0.132
What is the concn of the OH- in the satd soln? It is 0.132. That 15 mL is diluted to 250; now the concn is 0.132 x 15/250 = 0.00792M. We take 15 mL of that and titrate it with HCl.
mLOH- x MOH- = mLHCl x MHCl