If the OH− concentration in a bottle of an ammonia based cleaner is 3.8 × 10−² M,what is the H⁺ concentration? (K_w = 1.0 × 10−¹⁴)

Question

Quizplus · Accepted Answer

We can use the following equilibrium equation for ammonia: NH3 + H2O ⇌ NH4+ + OH- The equilibrium constant expression (Kw) for this equation is: Kw = [NH4+][OH-]/[NH3][H2O] Since the OH- concentration is given, we can rearrange the equilibrium constant expression to solve for the NH4+ concentration: [NH4+] = Kw/[OH-][NH3] Substituting the given values: Kw = 1.0 × 10-14 [OH-] = 3.8 × 10-12 [NH3] = assume to be very large, and thus can be considered constant. [NH4+] = (1.0 × 10-14)/(3.8 × 10-12) = 2.6 × 10-3 M Therefore, the H⁺ concentration is also 2.6 × 10-3 M, since there is a 1:1 stoichiometric ratio between NH4+ and H⁺ in this particular ammonia-based cleaner.

If the OH− Concentration in a Bottle of an Ammonia