Hi,

I got stuck on a silly easy question, and have a test soon. Was hoping someone could assist me.

I need to calculate the pH of a solution containing 2g of NaNO_{2} in 500ml. I know the Kb.

I know I need to solve it with one of the formulas:

H^{+}=(Ka X Ca)^0.5

or

HO^{-}= (Kb X Cb)^0.5

I know I can calculate the Ka since I know the Kb (pKa+pKb=pKw=14)

My problem is:

I calculated the concentration of NaNO2 (2g/mw/2). I don't understand how do I tell if this is Ca or Cb...

any help?

thanks .