In: Chemistry
Consider the diprotic acid H2X, where Ka1 = 1.75 x 10-5 and Ka2 = 4.3 x 10-12 at 25 °C. The concentration of HX- (aq) in a 0.125 M solution of H2X at 25 °C is approximately
E. none of these
first construct the ICE table and then substitute the
values in the K equation and then calculate the equilibrium values
as follows
H2X
----------------------------> HX- + H+
I 0.125 0 0
C -x +x +x
E (0.125-x) x x
Ka1 = [HX-] [H+] / [H2X]
=>1.75*10-5 = x2 / (0.125-x)
=> 1.75*10-5 * (0.125-x) = x2
=> x = 0.001479
=> 0.0015 => 1.5*10-3 M = [HX-] = [H+]
answer => c) 1.5*10-3 M