A 250 mL buffer solution is prepared with 0.300 M ammonia (NH₃) and 0.300 M ammonium…
CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases
Problem
A 250 mL buffer solution is prepared with 0.300 M ammonia (NH₃) and 0.300 M ammonium chloride (NH₄Cl). The base-dissociation constant of ammonia at 25 °C is Kb=1.8×10−5. The solution is then treated with 40.0 mL of 0.200 M HCl(aq).
(a) Calculate the pH of the buffer before any HCl is added.
(b) After the addition, determine the new amounts (in moles) of NH₃ and NH₄⁺ present following the neutralization reaction.
(c) Compute the concentrations of NH₃ and NH₄⁺ in the new total volume of solution and determine the final pH.