Calculate the ph of a solution prepared by adding 20.0 ml of 0.100 m hcl to 80.0 ml of a buffer that is comprised of 0.25 m c2h5nh2 and 0.25 m c2h5nh3cl. kb of c2h5nh2 = 9.5 x 10-4.

The pH of resulting solution is 10.893

Explanation:

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

Molarity of ethylamine solution = 0.25 M

Volume of solution = 80 mL

Putting values in above equation, we get:

Molarity of HCl = 0.100 M

Volume of solution = 20.0 mL

Putting values in above equation, we get:

Molarity of solution = 0.25 M

Volume of solution = 80 mL

Putting values in above equation, we get:

The chemical reaction for ethylamine and HCl follows the equation:

Initial:           0.02          0.002         0.02

Final:            0.018          -                0.022

Volume of solution = 20.0 + 80.0 = 100 mL = 0.100 L    (Conversion factor:  1 L = 1000 mL)

To calculate the pOH of basic buffer, we use the equation given by Henderson Hasselbalch:

We are given:

= negative logarithm of base dissociation constant of ethylamine =

pOH = ?

Putting values in above equation, we get:

To calculate pH of the solution, we use the equation:

Hence, the pH of the solution is 10.893