Problem 15.89 Hippuric acid (HC9H8NO3), found in horse urine, has pKa 3.62. Part

Question

Problem 15.89 Hippuric acid (HC9H8NO3), found in horse urine, has pKa 3.62. Part A Calculate the pH in 0.100 M hippuric acid. Express your answer using three significant figures. pH Submit My Answers Give Up Part B Calculate the concentration of H30 in 0.100 M hippuric acid Express your answer to two significant figures and include the appropriate units Value Units Submit My Answers Give Up Part C Calculate the concentration o C9H8NO3 in 0.100 M hippuric acid. Express your answer to two significant figures and include the appropriate units. Value Units Submit My Answers Give Up

Explanation / Answer

Let be the dissociation of the weak acid
                            HA <---> H + + A-

initial conc.            c               0         0

change                -c            +c      +c

Equb. conc.         c(1-)          c    c

Dissociation constant , Ka = c x c / ( c(1-)

                                         = c 2 / (1-)

In the case of weak acids is very small so 1- is taken as 1

So Ka = c2

==> = ( Ka / c )

Given pKa = 3.62

-log Ka = 3.62

Ka = 10-3.62 = 2.40x10-4

          c = concentration = 0.100 M

Plug the values we get = 0.0490

[H+] = [H3O+]= c = 0.100 x0.0490 = 4.90x10-3 M

pH = - log [H+]

    = - log(4.90x10-3)

    = 2.31

concentration of [A-] = c = 0.100 x0.0490 = 4.90x10-3 M

[HA] = c(1-) = 0.095 M

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

---