I am doing titration of NaOH with oxalic acid at school and none of my results are close together at all. I got 1. 26.6 mL 2. 27 mL (although I want to discount this since I wasn't very careful with this) 3. 25.5 mL 4. 26 mL 5. 25.3 mL (For this titration I realized that there was some insoluble material at the bottom of my conical flask. Thus I wanted to discount this as well for possible risk of contamination) Can someone explain any possible reasons for such large discrepancies? I have been very careful washed all my equipment etc. but still got bad results.