Ethylamine, , has . The temperature dependence of its base‐dissociation constant can…

CHEMISTRY · Subjective · A Level · Chemistry · Acids and bases · Acids and bases

Problem

Ethylamine,

C_2H_5NH_2

, has

K_b(25^{\circ}\text{C}) = 4.3\times10^{-4}

. The temperature dependence of its base‐dissociation constant can be approximated by

\log K_b(T) = \log K_b(298\,\text{K}) + 0.020\,(T-298)

. A buffer is prepared by mixing

50.0\,\text{mL}

0.500\,\text{M}

ethylamine with

25.0\,\text{mL}

0.500\,\text{M}

HCl, and then diluting the mixture to a final volume of

250\,\text{mL}

. Calculate the pH of this buffer after it is warmed to

37^{\circ}\text{C}

(310 K).