Le Châtelier's Principle

Prepare a solution of cobalt(II) chloride hexahydrate, predict each equilibrium shift and compare the reversible colour changes observed in real laboratory recordings.

What the student does

• Prepares a reference solution of cobalt(II) chloride hexahydrate and reviews the key aspects of the experimental procedure.
• Analyses the effect of adding hydrochloric acid to increase chloride concentration or water to change the equilibrium.
• Investigates the effect of temperature through heating and cooling.
• Predicts the direction of each equilibrium shift before observing the real experiment.
• Uses the observed colour changes to interpret the equilibrium shift and justify conclusions.

The activity includes guided predictions, immediate formative feedback and a final review of the main conclusions about the effects of concentration and temperature on chemical equilibria.