# Can the titrant and the unknown material be flipped?

We know the typical experiment of determining the concentration of $$\ce{Fe^2+}$$, where we titrate $$\ce{MnO4^-}$$ which has dark purple color and watch the color of the bottle.

Can we also determine the $$\ce{MnO4^-}$$ concentration using $$\ce{Fe^2+}$$ as titrant and how?

You can see that the iron is inside the beaker and we titrate with $$\ce{MnO4^-}$$. Can we do it backward, i.e. having $$\ce{MnO4^-}$$ inside the beaker with purple color and we titrate $$\ce{Fe^2+}$$.

• Yes and no. The titrant is picked to give a good end point detection. It is easier to see a color appearing than to see a color disappearing. – MaxW May 29 at 10:20
• For human eyes, it is much easier to observe colourless -> colour, than the other way around - so in this case, I'd say it won't work, but there might be other cases where it could by switching to a different indicator. – Martin - マーチン May 29 at 10:20
• Also, the equivalence point is light pink when using $\ce{MnO4-}$. Observing pink to light pink is way harder than observing colourless to light pink. – Aniruddha Deb May 29 at 12:03
• Refer primary standard solution – user600016 May 29 at 13:34
• Additional complication: the unknown substance has an unknown concentration. If you add it to the titrant, what if you don't have enough? – Zhe May 29 at 16:05