Final answer:
The correct answer is d.) The equilibrium concentration of [H3O+] in a 0.20 M HA solution with a Ka value of 1.0 × 10^-5 is 1.0 × 10^-5 M.
Step-by-step explanation:
To find the equilibrium concentration of [H3O+] in a 0.20 M HA solution, we can use the ionization constant (Ka) of the weak acid. The ionization constant is given as 1.0 × 10^-5.
Using an ICE table, we can set up the equation:
HA ⇌ H+ + A-
Initial: [HA] = 0.20 M, [H+] = 0 M, [A-] = 0 M
Change: -x, +x, +x
Equilibrium: [HA] = 0.20 - x, [H+] = x, [A-] = x
Since the equilibrium concentration of [H3O+] is equal to x, we can substitute x into the equation for [H3O+] and solve for x:
[H3O+] = x = 1.0 × 10^-5
Therefore, the equilibrium concentration of [H3O+] in the 0.20 M HA solution is 1.0 × 10^-5 M, which corresponds to option d.