ChairNoBill

I used Fe and Zn as electrodes, 40 ml of 0.1 molar ZnSO4 and 40ml of 0.1 molar FeSO4 as electrolytes. As saltbridge I used KCl. I did not change anything during my experiment meaning that I did not switch the electrolytes after trials. I can't explain why voltage increased, does anyone have an idea why this could have been the case?