A biochemical reaction must be run at pH 6.80 and

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

Problem

4^{\circ}\text{C}

. Two candidate buffers are listed below (values are for

25^{\circ}\text{C}

): • Buffer X:

pK_a = 6.60

\Delta pK_a/\Delta T = -0.015\,/^{\circ}\text{C}

• Buffer Y:

pK_a = 7.10

\Delta pK_a/\Delta T = -0.020\,/^{\circ}\text{C}

Which buffer provides the better match to the required pH at

4^{\circ}\text{C}

? Justify your selection by calculating the adjusted

pK_a

for each buffer at that temperature.