Revision notes topic questions past papers

Effects of temperature

Example:

•  Iodine Monochloride reacts reversibly with Chlorine to form Iodine Trichloride

ICl          +          Cl

2

             

⇌             ICl

3

                                  Dark Brown                                                         Yellow

When the equilibrium mixture is heated, it becomes dark brown in colour. Explain whether 

the backward reaction is exothermic or endothermic:

•  Equilibrium has shifted to the left as the colour dark brown means that more of ICI is 

produced

•  Increasing temperature moves the equilibrium in the endothermic direction

•  So the backward reaction is endothermic