# Why is oxalic acid often used as a standard in acid-base titrations?

And typically we use it as the dihydrate, i.e. $H O \left(O =\right) C - C \left(= O\right) O H \cdot 2 {H}_{2} O$, with a formula mass of $126.065 \cdot g \cdot m o {l}^{-} 1$.