Chemical Equilibrium

Abstract

Equilibrium chemistry occurs when the concentrations of reactants and products remain constant over time. If an external change affects the system, the reaction shifts to establish a new equilibrium, according to Le Chatelier's Principle. This experiment tested equilibrium involving iodine dissolved in two immiscible solvents: organic CCl4 and water. The aim was to identify factors affecting chemical equilibrium and to determine the equilibrium constants for the reaction I2 + I− ↔ I3−. Equilibrium is influenced by temperature, pressure, volume, and concentration. The reaction is reversible, meaning products can revert to reactants until equilibrium is reached. In this practicum, concentration and volume were observed. The method involved saturating I2 in CCl4 in two different Erlenmeyer flasks, then titrating the later solution with thiosulfate to measure I2 content. Titration was done quickly after adding starch indicator due to the importance of equilibrium time. Two experiments were conducted: the first to determine the distribution constant (KD) by measuring I2 in both CCl4 and water, and the second to find the equilibrium constant (KC) by adding KI solution to I2 in CCl4. The obtained values were KC = 66.176 M and KD = 32.