iTutor Chemistry Updates

Buffer solution = 5.85 x10^-3 mol of weak acid HY and 1.98 x10^-3 of the salt NaY The pH of the buffer solution is 3.78 (1.) Calculate the value of the Pka for the acid HY at this temperature. (2.) State and explain the effects on the pH of the buffer when a small amount of HCl is added. __________________________________________________ ____________________________ 3.78 = -log [x] 10^ [- 3.78] = x x = 1.66 x10^-4 = H+ ________________________________________ Now I think I should work out volume at this point So M = n/v ==> 1.66 x10^-3 = 5.85 x10^-3 / v 5.85 x10^-3 \ 1.66 x10^-3 = v v= 3.52 Maybe not.... __________________________________________________ __ If so then Ka = (1.66 x10^-3) (1.66 x10^-3) / 3.52 - 1.66 x10^-3 Ka = 2.76 x10^-6 / 3.51834 = 7.84 x10^-7 _________________________ PKa = -log [ka] - log [7.84 x10^-7] = 6.11