Need help finding pH

1. Dec 3, 2009

noob314

50.0mL of 0.100M HCN with pKa=8.21 is mixed with 50.0ml of 0.100M NaOH.

Since the equilibrium is towards the left, the change in the molarity of HCN is practically negligible, therefore giving it the same amount of moles as NaOH, which I assume they will both essentially neutralize each other giving a pH of 7. However, the correct pH value is 10.45, so I'm a little stuck on where to begin. Any help is appreciated, thanks.

2. Dec 3, 2009

Staff: Mentor

Hint: this is solution of a weak base.

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