Question

In: Chemistry

a) Why would there be a mathematical relation between the dissociation constant of a weak acid...

a) Why would there be a mathematical relation between the dissociation constant of a weak acid and the pH of a solution? Write the HH equation as a generalized mathematical expression.

b) What is the relation between the concentrations of a weak acid and its conjugated base when the pH of the solution is identical with the acid’s pKa? Explain

Solutions

Expert Solution

a) dissociation constant of a weak acid is expressed as

HA <-----> H+ + A-

Ka = (concentration of products/concentration of reactants)

HA <-----> H+ + A-        (let assume concentration of weak acid is 0.1 M)

0.1           0       0    initial

-x            +x     +x change

0.1-x        x       x    equilibrium

Ka = x^2/(0.1-x)

b) pH = pKa + log(salt/acid)

if concentration of salt = concentration of acid

pH = pKa

queen_honey_blossom answered 2 years ago
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