Answer:
pH = 9,32
Explanation:
The compound with 2 ionizable groups has the following equilibriums:
H₂M ⇄ HM⁻ + H⁺ pka = 6,2
HM⁻ ⇄ M²⁻ + H⁺ pka = 9,5
The reaction of M²⁻ with HCl is:
M²⁻ + HCl → HM⁻ + Cl⁻
The moles of M²⁻ are:
0,100L×1,0M = 0,1moles
And moles of HCl are:
0,060L×1,0M = 0,06moles
That means that moles of M²⁻ will be 0,1-0,06 = 0,04mol and moles of HM⁻ will be the same than HCl, 0,06mol
Using Henderson-Hasselbalch formula:
pH = pka + log₁₀ [M²⁻] / [HM⁻]
Replacing:
pH = 9,5 + log₁₀ [0,04] / [0,06]
<em>pH = 9,32</em>
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I hope it helps!
