When a 26.3 mL sample of a 0.465 M aqueous nitrous acid solution is titrated with a 0.461 M aqueous barium hydroxide solution, what is the pH after 19.9 mL of barium hydroxide have been added

The pH of the solution after addition of barium hydroxide is 3.78

Explanation:

To calculate the number of moles for given molarity, we use the equation:

     .......(1)

Molarity of nitrous acid = 0.465 M  

Volume of solution = 26.3 mL

Putting values in equation 1, we get:

Molarity of  barium hydroxide = 0.461 M  

Volume of solution = 19.9 mL

Putting values in equation 1, we get:

The chemical reaction for nitrous acid and barium hydroxide follows the equation:

Initial:       0.0122    0.0092          

Final:         0.003          -                0.0092

Volume of solution = 26.3+ 19.9 = 46.2 mL = 0.0462 L   (Conversion factor:  1 L = 1000 mL)

To calculate the pH of acidic buffer, we use the equation given by Henderson Hasselbalch:

We are given:

= negative logarithm of acid dissociation constant of nitrous acid = 3.29

pH = ?

Putting values in above equation, we get:

Hence, the pH of the solution after addition of barium hydroxide is 3.78

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