Question

Calculate the pH and the equilibrium concentrations of HSO₃^- and SO₃^2- in a 0.1770 M sulfurous acid solution, H₂SO₃ (aq).

For H₂SO₃, K_a1 = 1.7×10^-2 and K_a2 = 6.4×10^-8

pH =

[HSO₃^-] = _______ M

[SO₃^2-] = ______ M

Answer 1

Concentrati on of H2SO30.170M ICE table constructed is as foll ows; I(M)0.170 C(M)x E(M): (0.170-x) 1st aci dioni zati on constant, K. H2SO2 1.70x10 _(x)(x) (0.170-х 5.38x10 M H,38x10 M HSO,(a) H SO (a)H,0* (aa) From the equilibrium table, [H30-x-538x10-3M b) ICE table constructed for the 2ndionization of H2SO is as foll ows, I(M) 5.38x10 C(M) E (M) (538x102-x) 5.38x102 + X 5.38x102 +x 2nd acidionizati on constant, K -1 HS 64x10.(538x10%x)(x) 5.38x10-2- Since H.SO is a weak acid, itionizes to a little extent So, we can assume that 5.38x10"-x ~ 5.38x10 -2 5.38x102 +x 5.38x10-2 (538x10%) 6.4x10 (5.38x10 x 6.4x108 From the equilibrium table, [so,-- (x) M-64x10 M From the equilibrium table, [HO-(538x10,x)M (5.38x10+64x109)M 5.38x102 M Isa-]= (5.38×10-2-x)M 5.38x10-64x10M 5.38x10 M From the equilibrium table, pHlogH,o]log(538x10) -127