FAQs

Q: How do I know that my titration is finished? 

A: While dropping the potassium permanganate into your hydrogen peroxide sample, you'll likely notice that the pink will persist more and more as the peroxide is reacting. You'll know that your titration is finished when a faint pink appears in your solution. (TIP: If your lab bench is a dark color, you might want to put a piece of paper under your flask to see the pink earlier) 

Q: How do I know if I over titrated my sample? 

A: You've over titrated your sample if it is a very saturated or dark pink. That means that you let too much permanganate solution into your sample, and you should probably repeat your titration. 

Q: But what if I like the pretty dark pink? 

A: That's a shame. 

Q: Why is it so important to rinse the buret before you use it? 

A: Classrooms typically share burets, and you cannot always trust that the past class rinsed them from previous experiments. If there is an unwanted chemical in the buret, it could affect the concentration of you potassium permanganate, and could then mess up your results. So, always make sure to rinse with distilled water, and then two rinses with your titrant. 

Q: Why do we fill the buret slightly past the zero mark? 

A: Filling the buret slightly above the zero marks allows us to open the stopcock and release any stubborn air bubbles out of the buret before we begin our titration to avoid inaccurate results. Once you've released the air bubbles, the excess potassium permanganate will also drain, leaving you with permanganate at about the zero mark, depending on your accuracy.