Activity 12 Chemical Equilibrium Le Chatelier's Principle PDF

Activity 12 CHEMICAL EQUILIBRIUM: Le Chatelier’s Principle At the end of the exercise, the students must have to: (1) observe and understand the concept of reversible reactions; (2) apply Le Chatelier’s Principle to predict the direction of equilibrium shift in response to various disturbances; (3)...

Activity 12 CHEMICAL EQUILIBRIUM: Le Chatelier’s Principle At the end of the exercise, the students must have to: (1) observe and understand the concept of reversible reactions; (2) apply Le Chatelier’s Principle to predict the direction of equilibrium shift in response to various disturbances; (3) determine whether the reaction between ferric nitrate and potassium thiocyanate is endothermic or exothermic based on observed color changes under different temperature conditions. A reversible reaction is one where both the forward (reactants forming products) and reverse (products forming reactants) reactions occur simultaneously. Initially, the forward reaction is fast due to high reactant concentrations, but it slows down as reactants are consumed. Conversely, the reverse reaction speeds up as products are formed. Eventually, the rates of both reactions become equal, reaching dynamic equilibrium, where the concentrations of reactants and products remain constant. Le Chatelier's Principle states that when a system at equilibrium is disturbed (e.g., changes in concentration, pressure, or temperature), it will shift to counteract the disturbance and restore equilibrium. In this experiment, changes in concentration and temperature will be studied for the reaction between ferric nitrate and potassium thiocyanate: Fe3+(aq) + SCN –(aq) ⇋ FeSCN 2+(aq) Yellow Colorless Red Procedure CAUTION 1. Handle all chemicals with care and wear appropriate personal protective equipment, including gloves and goggles, to prevent skin contact and eye irritation. 2. Handle hot water and ice baths cautiously to prevent burns or injuries. 3. Dispose of chemical waste according to laboratory safety protocols and guidelines. 1. Place 30 mL of distilled water in a 50-mL beaker. Add 15 drops of 0.1 M Fe(NO3)3 and 15 drops of 0.1 M KSCN. Stir to homogenize the mixture. 2. Place 3 mL of the prepared solution into seven separate test tubes. Test tube 1 serves as the control. 3. To test tubes 2 to 5, add the following: Test tube 2 - three drops of 0.1 M Fe(NO3)3 Test tube 3 - three drops of 0.1 M KSCN Test tube 4 - three drops of 0.1 N AgNO3 Test tube 5 - three drops of 0.1 N NaF Shake the contents in each tube and compare the color of the resulting solution with that of the control. Determine the shift in equilibrium position in each test tube. 4. Place test tube 6 in an ice water bath for five minutes. Compare the color of the solution with the control. To which direction did the equilibrium position shift? 5. Place test tube 7 in hot water bath. Compare the color of the solution with the control. To which direction did the equilibrium position shift? 6. From the results obtained in Procedures 4 and 5, is the reaction between ferric nitrate and potassium thiocyanate endothermic or exothermic? Activity 12 Le Chatelier’s Principle Name: Date: Section: Schedule: Group number: Score Net chemical equation for the reaction of ferric nitrate and potassium thiocyanate: ______________________________________________________________________ Color of Control Solution: ____________________________ Fill in the table below. Test Tube Reagent Added / Process Color of Equilibrium Shift # Performed Solution/Mixture (Forward/Backward) 2 3 4 5 6 7 Answer as Directed 1. Explain the result obtained in Test Tube 2. _______________________________________________________________________________________________ ___________________________________________________________________________________________________ ___________________________________________________________________________________________________ 2. Explain the result obtained in Test Tube 4. _______________________________________________________________________________________________ ___________________________________________________________________________________________________ ___________________________________________________________________________________________________ 3. What is/are the formula/s of the predominant ion/s present in Test tube 6: _________________________ 4. What type of reaction (Endothermic/Exothermic) is the chemical system considered in this experiment? _________________________ Why? ___________________________________________________________________________________________________ ___________________________________________________________________________________________________ 5. Explain how Le Chatelier's Principle applies to biological systems. Can you think of an example in living organisms where equilibrium is essential, and external factors (e.g., temperature, pH) can shift the equilibrium position? __________________________________________________________________________________________________ __________________________________________________________________________________________________