The pH of a 0.55 M aqueous solution ammonia, NH₃, at 25.0°C is 11.50. What is the value of K_b for NH₃? A)2.0 × 10^-⁹ B)1.1 × 10^-⁹ C)6.0 × 10^-⁵ D)1.8 × 10^-⁵ E)none of the above

Question

Quizplus · Accepted Answer

The Kb expression for ammonia is:

Kb = Kw / Ka 
Kb = 1.0 × 10^-14 / 1.8 × 10^-5 
Kb = 5.6 × 10^-10

Now, let's use the relationship between Kb and Ka:

Kw = Ka × Kb 
1.0 × 10^-14 = Ka × 5.6 × 10^-10

Solving for Ka:

Ka = 1.8 × 10^-5

So the answer is D, 1.8 × 10^-15.

The PH of a 0