A buffer solution is prepared by dissolving 0.050 mol of NH and 0.010 mol of NH Cl in…

CHEMISTRY · Single correct · A Level · Chemistry · Acids and bases · Acids and bases

Problem

A buffer solution is prepared by dissolving 0.050 mol of NH

_3

and 0.010 mol of NH

_4

Cl in water to make 1.00 L of solution at 25 °C. The base-dissociation constant of ammonia is

K_b = 1.8\times10^{-5}

. What is the equilibrium concentration of OH

^-

in the solution? (Assume the change in concentration upon reaction is negligible compared with initial concentrations.) (a)

4.5\times10^{-4}\;\text{M}

(b)

3.6\times10^{-5}\;\text{M}

(c)

9.0\times10^{-5}\;\text{M}

(d)

1.8\times10^{-5}\;\text{M}