Illustration of Le Chatelier's principle using the reaction between FeCl3 and Potassium Thiosulfate

Write an equation for the experiment to illustrate Le Chatelier’s principle

Iron (III) Chloride + Potassium Thiocynate ⇌ Ferrocyothyate + Chloride ions

Fe³⁺Cl₃^- + CNS^- ⇌ Fe(CNS)²⁺ + 3Cl^-

yellow colourless red

- delta H

Method to show the effect of temperature

• add FeCl₃ to a test-tube with potassium thiocyanate

• observe the colour

• heat the solution + note colour change

  • colour becomes more yellow

  • equilibrium shifts to the left

• cool the solution + note the colour change

  • red colour intensifies

  • equilibrium shifts to the right

Method to show the effect of concentration

• add FeCl₃ to a test tube with KCNS

• observe the colour

• add conc. HCl to the solution + note change

  • becomes more yellow

  • equilibrium shifts to the left

• KCNS is added + note change

  • red colour intensifies

  • equilibrium shifts to the right

lol