posted by Sierra on .
aqueous sulfurous acid H2SO3 was made by dissolving 0.200 L of sulfur dioxide gas at 19 C and 745 mm Hg in water to yield 500.0 ml of solution. the acid solution required 12.9 ml of sodium hydroxide solution to reach the titration end point. what was the molarity of the sodium hydroxide solution?
SO2 + H2O ==> H2SO3
Use PV = nRT to determine the mols SO2. Don't forget T must be in Kelvin. Since the equation is a 1:1 ratio for SO2 to H2SO3, that will be the number of moles H2SO3.
Then for the titration. You don't say WHICH end point; I assume the NaOH titrates all of the H2SO3 (both H ions).
2NaOH + H2SO3 ==> Na2SO3 + 2H2O
moles H2SO3 = ??
moles NaOH is 2 x that.
Then M NaOH = moles NaOH/L NaOH.