1.0 LL of a buffer is prepared. It contains 0.125 M HAM HA (pKapKa = 4.74) and 0.115 M A−M A−. What is the pH of this buffer after 0.0100 molmol of strong acid is added?

pH of buffer before addition of Strong acid = 4.71

pH of buffer after addition of Strong acid = 2

Explanation:

According to Henderson's equation

⇒pH = pKa +㏒

⇒pH = 4.74 + log()

⇒pH = 4.74 - 0.03

⇒pH = 4.71

⇒[H⁺] = 1.9 x 10⁻⁵

pH of this buffer after 0.01 mole of strong acid addition

⇒pH = - log[H⁺]

⇒pH = - log(1.9 x 10⁻⁵ + 0.01)

⇒pH = 2