Answer:
2.17x10⁻¹⁰ = Kb1
1.69x10⁻¹³ = Kb2
Explanation:
Oxalic acid, C₂O₄H₂, has two intercambiable protons, its equilibriums are:
C₂O₄H₂ ⇄ C₂O₄H⁻ + H⁺ Ka1 = 5.9x10⁻²
C₂O₄H⁻ ⇄ C₂O₄²⁻ + H⁺ Ka2 = 4.6x10⁻⁵
Oxalate ion, C₂O₄²⁻, has as equilibriums:
C₂O₄²⁻ + H₂O ⇄ C₂O₄H⁻ + OH⁻ Kb1
C₂O₄H⁻ + H₂O ⇄ C₂O₄H₂ + OH⁻ Kb2
Also, you can know: KaₓKb = Kw
<em>Where Kw is 1x10⁻¹⁴</em>
Thus:
Kw = Kb2ₓKa1
1x10⁻¹⁴ =Kb2ₓ4.6x10⁻⁵
<h3>2.17x10⁻¹⁰ = Kb1</h3>
And:
Kw = Kb1ₓKa2
1x10⁻¹⁴ =Kb1ₓ5.9x10⁻²
<h3>1.69x10⁻¹³ = Kb1</h3>
<em>That is because the inverse reaction of, for example, Ka1:</em>
<em>C₂O₄H⁻ + H⁺ ⇄ C₂O₄H₂ K = 1 / Ka1</em>
<em>+ H₂O ⇄ H⁺ + OH⁻ K = Kw = 1x10⁻¹⁴</em>
<em>= </em>
<em>C₂O₄H⁻ + H₂O ⇄ C₂O₄H₂ + OH⁻ Kb2 = Kw × 1/Ka1</em>
