What is the pH of a solution that results when 0.012 mol HNO₃ is added to 670.0 mL of a solution that is 0.26 M in aqueous ammonia and 0.48 M in ammonium nitrate. Assume no volume change. (K_b for NH₃ = 1.8*10^-⁵.)

Question

Quizplus · Accepted Answer

The correct answer is A.The reaction between HNO3 and NH3 is:HNO3 + NH3 -> NH4NO3The moles of HNO3 added are:0.012 mol HNO3 * (1 mol NH3 / 1 mol HNO3) = 0.012 mol NH3The total moles of NH3 in the solution are:0.012 mol NH3 + (0.26 M NH3 * 0.670 L) = 0.184 mol NH3The total volume of the solution is:0.670 L + 0.012 L = 0.682 LThe concentration of NH3 in the solution is:0.184 mol NH3 / 0.682 L = 0.27 M NH3The pOH of the solution is:pOH = -log[OH-] = -log(Kw / [H+]) = -log(1.0 * 10^-14 / 10^-8.94) = 5.06The pH of the solution is:pH = 14 - pOH = 14 - 5.06 = 8.94

What Is the PH of a Solution That Results When