Answer to Question #198604 in General Chemistry for morongoa

Question

Calculate the pH of a solution that was prepared by mixing 25.00 mL of a 0.1630 M HClO4 solution with 20.00 mL of a 0.1350 Ba(OH)2 solution

Answer 1

pH is a parameter which is used to determined the acidity or basicity of an aqueous solution. 

pH is determined by the concentration of either H⁺or OH^- ion concentration.

pH = -log[H⁺]

pOH = -log[OH^-]

HClO₄ Strong Acid

V₁=25mL

M₁=0.1630M

n₁=1(total change of a cation or anion)

Ba(OH)₂ strong base

V₂=20mL

M₂=0.1350M

n₂=2

Ba²⁺+2(OH^-)

N.o. of H⁺ ion In HClO₄^-

n₁M₁V₁=1×25×0.1630=4.075

N. o. Of OH^- ion from Ba(OH)₂

n₂M₂V₂=2×20×0.1350=5.4

Hence n₂M₂V₂>n₁M₁V₁

[OH^-]= $\frac{5.4-4.075}{20+25}$

$=0.02944$

pOH=-log[OH^-]

=-log(0.02944)

pOH =1.53

But pH=14-pOH

=14-1.53

=12.47

pH=12.47