What is the actual concentration of molecular NH₃ in a 0.200 M solution of ammonia? The
K_b value for ammonia is 1.80 *10^-⁵.

Question

What is the actual concentration of molecular NH₃ in a 0.200 M solution of ammonia? The K_b value for ammonia is 1.80 *10^-⁵.

Quizplus · Accepted Answer

To solve this problem, we need to use the equilibrium expression for the reaction NH3 ⇌ NH2- + H+. The K_b value of 1.80 F1F1F1S1F1F1F10 10^-⁵ represents the equilibrium constant for this reaction. We can use the following equation to find the concentration of NH2- in the solution: K_b = [NH2-][H+]/[NH3] 1.80 F1F1F1S1F1F1F10 10^-⁵ = [x][x]/[0.200 - x] where x is the concentration of NH2-. Because x is much smaller than 0.200 M (since the dissociation of NH3 is small), we can assume that 0.200 - x ≈ 0.200. Solving for x gives: x = sqrt(K_b * [NH3]) = sqrt((1.80 F1F1F1S1F1F1F10 10^-⁵) * 0.200) = 0.198 M Therefore, the actual concentration of NH2- (which is the same as the concentration of H+) in the solution is 0.198 M. The correct answer is (B).

What Is the Actual Concentration of Molecular NH3 in a 0.200

What Is the Actual Concentration of Molecular NH₃ in a 0.200