posted by Anonymous .
How many grams of NaNO2 should be dissolved in 500cm3 solution of nitrous acid (HNO2) with concentration of 0.03mol/dm3 if we wish the solution to show a pH of 3.2
Ka = 4.5 * 10^-4
M(NaNO2) = 69 g/mol
Use the Henderson-Hasselbalch equation.
pH = pKa + log (base)/(acid)
You have pH, pKa, and (acid); solve for (base) and convert to grams in 500 cc.