Question

PLEASE SHOW WORK

4. Calculate the [H+], pH and percent dissociation of a solution that is 0.50 M in HOCl and 0.60 M in NaOCl.

5. Calculate the [H+], pH and percent dissociation of a solution that is 1.0 M in aniline (C6H5NH2) and 1.2 M in C6H5NH3Cl.

6. A solution contains 0.60 mol of NH4Cl and 0.30 mol of NH3 in 1.5 L. What is the pH if 0.070 mol of HCl is added to this buffer?  

Answer 1

4.

pH = pka + log(NaOCl/HOCl)

pka of HOCl = 7.53

    = 7.53+log(0.6/0.5)

    = 7.61

[H+] = 10^(-pH)

    = 10^(-7.53) = 2.951*10^(-8) M

[H+] = C*X

2.951*10^(-8) = 0.5*X

X = 5.902*10^(-8)

percent dissociation = 5.902*10^(-8)*100

   = 5.902*10^-6%

5. pOH = pkb + log(salt/amine)

         = 9.4 + log(1.2/1)

         = 9.5

   pH = 14-9.5 = 4.5

[H+] = 10^(-4.5) = 3.163*10^-5 M

[H+] = C*X

3.163*10^-5 = 1*X

X = 3.163*10^-5

percent dissociation = 3.163*10^-3

6. pOH = 4.74 + log((0.6+0.07)/(0.3-0.07))

      = 5.2
pH = 14-5.2 = 8.8