Calculate the percent ionization of benzoic acid for the following concentration (a) 0.40 M, (b) 0.00040 M

The pKa for benzoic acid is 4.2 (had to look it up)

This means the Ka is 6.3 x 10^-5

Let benzoic acid be represented by HA

HA > H A-

Ka = [H ][A-]/[HA]

For HA = 0.4 M Ka = (x)(x)/0.4 assuming that x is small relative to 0.4

x^2 = 6.310^-5 (0.4) = 2.610^-5

x =5.110^-3 M = [H ] = [A-]

For % ionization, it would be (5.110^-3/0.4) x 100 = 1.27% ionized

Do the same for 0.0004 by substituting this value for 0.4 in the denominator and then do the math

This post is last updated on hrtanswers.com at Date : 1st of September – 2022