Question

When 0.20 M NH₄Cl(aq) and 0.20 M NaOH(aq) are mixed, the reaction represented by the equation above occurs and a strong smell of ammonia, NH₃, is observed. Based on this information, which of the following statements is true?

A). NH₄⁺ (aq) acts as a Bronsted-Lowry base.
B). NH₄⁺ (aq) is a stronger acid than H₂O(l) is.
C). NH₃(aq) is a stronger base than OH⁻(aq) is.
D). NH₄⁺ (aq) and CL⁻(aq) are a conjugate acid-base pair.

Answer 1

NH₄⁺ (aq) acts as a Bronsted-Lowry acid when mixed with NaOH and the resulting smell of ammonia confirms the formation of NH₃, not as a base as needed for the correct option A). The correct statement is B) NH₄⁺ (aq) is a stronger acid than H₂O(l) is.

Step-by-step explanation:

When 0.20 M NH₄Cl(aq) and 0.20 M NaOH(aq) are mixed, and ammonia smell is observed, it indicates a reaction where NH₄⁺ behaves as an acid, not a base. The correct statement is that NH₄⁺ (aq) is a stronger acid than H₂O(l) is. This is due to the reaction NH₄⁺ (aq) + H₂O(l) ⇒ H₃O⁺ (aq) + NH₃(aq), which shows the ammonium ion releasing a proton to water, thus acting as a Bronsted-Lowry acid. Furthermore, NH₄⁺ and Cl⁻ are not a conjugate acid-base pair; NH₄⁺ and NH₃ are the correct conjugate acid-base pair.