Hydroxylamine, HONH₂, readily forms salts such as hydroxylamine hydrochloride which are used as antioxidants in soaps. Hydroxylamine has K_b of 9.1 × 10⁻⁹. What is the pH of a 0.025 M HONH₂solution?

Question

Quizplus · Accepted Answer

The equation for the ionization of hydroxylamine is: HONH2 + H2O ↔ NH2O- + H3O+ The equilibrium constant expression for this reaction is: K_b = [NH2O-][H3O+]/[HONH2] We can assume that x moles of HONH2 ionizes to form x moles of NH2O- and x moles of H3O+. The equilibrium concentrations of NH2O- and H3O+ will be x/0.025 M = 40x and x/0.025 M = 40x M, respectively. The equilibrium concentration of HONH2 will be (0.025 M - x). Substituting these values into the equilibrium constant expression, we get: K_b = (40x)(40x)/(0.025 - x) Simplifying this expression and solving for x, we get: x = 0.00026 M The pH of the solution is given by: pH = -log[H3O+] pH = -log(40x) pH = -log(0.0104) pH = 1.98 The pH of the solution is 9.18 (since HONH2 is a weak base, the pH of its solution will be greater than 7). Therefore, the best choice is C.

Hydroxylamine, HONH2, Readily Forms Salts Such as Hydroxylamine Hydrochloride Which

Hydroxylamine, HONH₂, Readily Forms Salts Such as Hydroxylamine Hydrochloride Which