A 400.0 ml sample of 0.10 mba (oh) 2 is titrated with 0.10 mhbr. determine the ph of the solution before the addition of any hbr.

Ba (OH) 2 is an basic solution. It has more OH - ions than H + ions. pOH should be calculated to find out its pH

The reaction is

Ba (OH) 2 ⇒ Ba2 + (aq) + 2 OH - (aq)

One mole barium hydroxide releases 2 moles hydroxide ions.

Use that ratio to calculate molarity (M) of OH - ions [OH-]. The ratio is 1:2.

0.10 M Ba (OH) 2 release 2*0.10 M = 0.02 M OH - ions

[OH-] = 0.02

pOH = - log [OH-] = - log 0.02 = 1.7

Thats not the answer! We found pOH of the solution before titration.

pH and pOH relationship is shown by formula of pH+pOH = 14

pH = 14-pOH

pH = 14-1.7 = 12.3