Le Chatelier Principle

Chemical Equilibrium: Le Châtelier’s Principle

Amanda Wong En-Huay

Chemistry 12, Canadian Pre-University, Taylor's College Subang Jaya, Wisma Subang Jaya SS15/4, 47500.

Abstract

This experiment entitled "Chemical Equilibrium" aims to help students to investigate the effects of concentration and temperature upon the position of equilibrium in a cobalt chloride solution, Co(H2O)62+. In this experiment, cobalt crystal is dissolved with distilled water and ethanol which the initial colour is purple-pinkish and a few drops of concentration of HCl is added to the test tube, the final colour is in deep blue colour. Upon the effect of concentration and temperature, the equilibrium will shift backward in the reaction with accordance with Le Chatelier's principle producing more HCl molecules. This means that equilibrium rate of forward and backward reactions were met. In result, this reaction is endothermic.

Introduction

Chemical equilibrium is the state in which a chemical reaction proceeds at the same rate as its reverse reaction; the rate of forward and reverse reaction are equal, and the concentration of the reactants and products stop changing1. When this condition was met, there was no change in the proportions of the various compounds involved, and the reaction ceases to progress.

The equilibrium state has a dynamic – that is, active – nature being characterized by the simultaneous and continuous formation of products from the reactants and reactants from the products2. But these simultaneous reactions do not necessarily follow that the concentrations of the reactants is equal to that of the product(s). Instead, the ratio of the concentrations of the reactants to the concentration of the product(s) raised to their coefficient in the balanced equation is Keq, a constant.

Taking the Le Chatelier’s principle into consideration, there are factors that may shift or influence the position of equilibrium4. The Le Chatelier’s principle states that if stress is...