10.2 - Reaching an Equilibrium State

• iodine is cyclohexane

  both are non-polar so molecules mix

  there's no reaction

  solution is purple-violet (the same as iodine vapour)
• iodine in potassium iodide

  dissolves

  solution is yellow, orange or brown depending on the concentration

  I2 and I- form triiodide ions I3^-
• how can equilibrium be demonstrated using iodine in cyclohexane and potassium iodide?

  they form separate layers when put in test tubes so have different concentrations of iodine which gives a different colour

  as you shake the test tube, concentration of iodine changes

  after a while when there's no further change in colour equilibrium has been reached
• rate and concentration at equilibrium

  concentrations of reactants and products remain constant

  rates of forward and backward reactions are the same