At 25 ^$\circ$C, the base ionization constant for NH₃ is 1.8 * 10^-5. Determine the hydroxide ion concentration in a 0.150 M solution of ammonia at 25 ^$\circ$C.

Question

Quizplus · Accepted Answer

The base ionization constant expression for ammonia is:

NH3 + H2O ⇌ NH4+ + OH-

The equilibrium constant expression, K, is:

Kb = [NH4+][OH-]/[NH3]

We can use the equilibrium constant expression and the given Kb value to find the hydroxide ion concentration in a 0.150 M solution of ammonia. First, we need to find the concentration of NH3:

0.150 M NH3 = [NH3]

Next, we can use the Kb value to calculate the concentration of OH-:

Kb = [NH4+][OH-]/[NH3]
1.8 × 10^-5 = x^2/0.150
x^2 = 2.7 × 10^-6
x = 1.6 × 10^-3 M

Therefore, the hydroxide ion concentration in a 0.150 M solution of ammonia at 25°C is 1.6 × 10^-3 M, which is equivalent to 1.6 × 10^-10 M (in scientific notation with pH values). The correct answer is C.

At 25 ∘\circ∘ C, the Base Ionization Constant for NH3 Is 1

At 25 ^$\circ$C, the Base Ionization Constant for NH₃ Is 1