Equil shows you what occurs as equilibrium is established at the molecular level. Le Chatelier's principle can also be examined by changing the temperature or concentration of the reaction mixture.The reaction can be run at 25-C or 35-C. The starting temperature for any new reaction is 25-C. The temperature can be changed to 35-C by selecting the desired temperature from the dialog box. The time is then reset to zero and you can see which way the equilibrium shifts (Le Chatelier's principle) when the temperature is changed. This also gives you an indication as to whether the reaction is endothermic (absorbs heat) or exothermic (evolves heat).