Question

Molarity of KMnO4:0.2M
Volume of H2O2: 10mL
Initial volume 50mL
Final Volume: 31.90mL
Volume of KMnO4 (new H2O2)
Would it be the 31.90mL or do I subtract 50mL-31.90mL= 18.10mL

Answer 1

Your question is confusing because you have a new H2O2 and we don't know if that is the 10 mL or not. In addition, you don't label the 50 mL and 31.90 mL. I suspect your question is that you started with a full buret of KMnO4 at 50 mL and you used down to 31.90 mL KMnO4. Therefore, you subtract. The amount of KMnO4 used to titrate the H2O2 was 50.00 mL - 31.90 mL = the 18 or so you have in the post. (I assume the 50 mL you wrote actually means 50.00 mL.)