If the ionization constant of water,K_w,at 40°C is 2.92 × 10^-14,then what is the hydronium ion concentration and pH for an acidic solution? A)[H₃O⁺] 1.71 × 10^-7 M and pH 6.77 B)[H₃O⁺] 1.71 × 10^-7 M and pH

Question

If the ionization constant of water,K_w,at 40°C is 2.92 × 10^-14,then what is the hydronium ion concentration and pH for an acidic solution? A)[H₃O⁺] > 1.71 × 10^-7 M and pH > 6.77 B)[H₃O⁺] > 1.71 × 10^-7 M and pH < 6.77 C)[H₃O⁺] < 1.71 × 10^-7 M and pH > 6.77 D)[H₃O⁺] < 1.71 × 10^-7 M and pH < 6.77

Quizplus · Accepted Answer

For an acidic solution, the hydronium ion concentration will be greater than the concentration of OH- ions. Using the ionization constant of water:
KW = [H+][OH-] = 2.92 × 10^-14
Assuming x is the concentration of H+ ions, then:
x * (x/KW) = x^2 / KW = [H+]^2 / KW = [H3O+] = 1.71 × 10^-7 M
Using the equation for pH: pH = -log[H3O+], we can find the pH:
pH = -log(1.71 × 10^-7) = 6.77, which is less than 7 (neutral), indicating an acidic solution.
Therefore, the correct choice is B.

If the Ionization Constant of Water,Kw,at 40°C Is 2

If the Ionization Constant of Water,K_w,at 40°C Is 2