Question

1. a.) What is the pH of a solution created by combining 1.27 mole of HOBr and 0.43 mole NaOH in a 1.00L solution? Ka HOBr = 2.5 x 10-9

b.)What is the pH of a buffer made by combining 0.98 moles HOBr with 0.67 moles NaOBr in a 100.00mL solution? Ka HOBr = 2.5 x 10-9

Answer 1

    HOBr       +    NaOH                 -------->        NaOBr +      H₂O

          1.27                  0.43

         1.27 -0.43          0.43 -0.43 =0

         = 0.84              0.43 0

Its a buffer solution , acidic buffer

So

pH = pka + log(salt/acid)

    = -log(2.5x10^-9 ) + log ( 0.43/0.84)

   = 8.6 + (-0.29) = 8.3

b) its a also an acidic buffer solution

pH = pka + log(salt/acid)

    = -log(2.5x10^-9 ) + log ( 0.67/0.98)

    = 8.6 +   (-0.16)         = 8.43