# How can you tell how much actually reacted in an acid base reaction

If you facilitate a weak acid base reaction. i.e. $\ce{NaOH + H2SO4}$. All of it may not react and the solutions will not neutralize. How can you determine how much actually reacted?

• Welcome to Chemsitry.SE. There is a way to determine the extent of reaction of weak acids and weak bases using equilibrium calculations. However, your acid/base pair of choice is a strong acid $(\ce{H2SO4})$ and a strong base $(\ce{NaOH})$. Assuming you have stoichiometric equivalence between the two, this reaction will go to completion. – Ben Norris Nov 13 '13 at 12:03
• @BenNorris that would also be true with a weak acid and a strong base. One should also consider that $\ce{H2SO4}$ is not that strong on the second ionization. – mannaia Mar 21 '14 at 14:58
• @fp I think you are right. you should answer the question writing it is not a good praxis use comment to answer the question .. – G M Mar 22 '14 at 9:11

As noted by Ben in the comment, $\ce{NaOH}$ and $\ce{H_2SO_4}$ are strong base and acid, respectively, so they will react till one is completely used up. Those react in 1:2 molar ratio, so it would be easiest to determine if you have more moles of one or another, and it will simply react, using one mole of $\ce{H_2SO_2}$ per two moles of $\ce{NaOH}$, until there is only one left. If there is one left, you will have a non-neutral solution in the end.