A weak base has

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

Problem

A weak base

\mathrm{B}

has

K_b = 1.8\times10^{-5}

. For which initial concentration of

\mathrm{B}

is the assumption that the change in concentration is negligible ("

x\ll C_0

") MOST justified when calculating the pH? (a)

1.0\times10^{-2}\,\text{M}

(b)

7.2\times10^{-3}\,\text{M}

(c)

1.0\,\text{M}

(d)

1.0\times10^{-3}\,\text{M}