0.10 mol of solid sodium hydrogen carbonate and 0.20 mol of solid sodium carbonate are dissolved in the same beaker of water, transferred to a volumetric flask and made to 250.0 mL. The Ka for HCO3 - is 4.7 x 10-11. What is the pH of the resulting buffer?

1 Answer
Apr 8, 2014

Use the Henderson-Hasselbalch equation to estimate the pH of any buffer solution based on the concentration ratio of base and conjugate acid and the Ka value of the acid.

Details of the calculation:

#pH = pK_a + log_(10)((A^-)/(HA)) = -log_(10)(4.7times10^(-11))+log_(10)((0.2)/0.1)#

#pH = 10.3+0.3=10.6#