Science Buddies: "Ask an Expert"

My experiment is exploring the effects of different levels of oxygen exposure on the concentration of vitamin c in orange juice over time.

I was titrating samples of the juice using iodine and had each day increase the amount of iodine needed. However, this meant that the Vitamin C content was increasing over time and not decreasing like it was supposed to do due to oxidation. Have I done something wrong?

Hi PeCachem,

You're right, that sounds like its going in the wrong direction. Can you give us the specifics of your experimental design? My only thought right now is that the concentrations between samples are different. Is the volume of juice and amount of starch in each condition exactly the same? Was your starch fully dissolved before you added it to the juice?
My only other thought is that as time goes on you're titrating more quickly, and possibly missing the equilibrium point.

Tell us your specific protocol, and we'll see if we can figure this out!