An experiment was carried out in class. Basically, Baking Soda was added to different concentrations of Ethanoic Acid. The plot of 'Maximum Foam observed' vs. 'concentration of the Acid'. The curve went up but then dropped noticeably! So basically, with high concentrations or low concentrations; the foam created was low. it was as if there was an optimal concentration? Note that this experiment was very fair. So Error? or something else?