Determine the number of milliliters of 0.00300 M phosphoric acid required to neutralize 40.00 mL of 0.00150 M calcium hydroxide.

The volume of H₃PO₄ : 13.33 ml

Given

0.003 M  Phosphoric acid-H₃PO₄

40 ml of 0.00150 M Calcium hydroxide-Ca(OH)₂

Required

Volume of H₃PO₄

Solution

Acid-base titration formula  

Ma. Va. na = Mb. Vb. nb  

Ma, Mb = acid base concentration  

Va, Vb = acid base volume  

na, nb = acid base valence  (amount of H⁺/OH⁻)

H₃PO₄⇒3H⁺ + PO₄³⁻ ⇒ 3 H⁺ = valence = 3

Ca(OH)₂⇒Ca²⁺ + 2OH⁻⇒ 2 OH⁻ = valence = 2

Input the value :

a = H₃PO₄, b = Ca(OH)₂

0.003 x Va x 3 = 0.0015 x 40 x 2

Va = 13.33 ml