For each of these desired pH values choose a weak acidconjug

For each of these desired pH values, choose a weak acid-conjugate base pair from your textbook that could be used to prepare a buffer solution with that pH Calculate the desired [A VIHA] ratio in each case. (a) pH = 6.00 1. (b) pH = 8.00 (c) pH = 11.00 2. 500 mL of a buffer solution contains 0.050 mol NaHSO3 and 0.031 mol Na2SO3 (a) What is the pH of the solution? (b) Write the net ionic equation for the reaction that occurs when NaOH is added to this buffer. (c) Calculate the new pH after 10. mL of 1.0 M NaOH is added to the buffer solution. (d) Calculate the new pH after 10. mL of 1.0 M NaOH is added to 500. mL of pure water. (e) Explain why the pH of the water changed so much as compared to the pH of the buffer.

Solution

Buffer solution can resist the changes of pH when small amount of acid or base is added.

A buffer solution of NaHSO₃ and Na₂SO₃ ; some amount of undissociated NaHSO₃is in equlibrium with Na⁺ and HSO₃^- ion whereas some amount of undissociated Na₂SO₃ is in equlibrium with Na⁺ and SO₃^2- ion.

Therefore in the equlibrium Na⁺ is the common ion. Now when small amount of acid and base is added it reacts with Na⁺ ion and shifted the equlibrium to the left side (by La-chatelier\'s principle) , hence pH of the solution remains unchanged.

But water is amphoteric it can accept both H⁺ and also can donate H⁺ , so when small amount of acid and base is added pH of water will change .

That is why pH of the water has changed so much but as compared to the pH of the buffer.