Samuel Brown & Himesh Premalal Monday April 23rd, 2018
Chemical Equilibrium: Reversible Reactions
Introduction: The objective of the experiment is to study the effect of stress on the position of equilibrium. This lab focused on the concept of equilibrium and how it can be shifted either to the left or to the right by adding or removing parts of the equation. Chemical equilibrium can be understood as when the forward reaction is equal to the reverse reaction. The goal of the experiment was to see this equilibrium by observing the color change and determining what color changes mean in terms of the reaction and equilibrium of the reaction. Equilibrium is able to be understood through Le Chatelier’s principle, which states that a system at equilibrium will stay at equilibrium. The concept can be better understood by realizing that the system will balance the equilibrium when another chemical or substance is added to it. When the system reaches equilibrium, it will not come out of it. Equilibrium is represented by a double arrow between the reactants and products, meaning that the formation of reactants and products is constant. During the lab, there were many substances that were added to systems to observe the equilibrium. When the substances are added, the system is interrupted, so the equilibrium is shifted to one side of the reaction, which depends on the substance that is added. The principle states that when the system is changed, the chemicals will try to keep it balanced again. Observing changes within the system is observing the system shift to one side of the reaction, then coming back to equilibrium once again.
This experiment was started by preparing a stock solution of 1 ML iron(III) chloride, potassium thiocyanate and 50 mL of distilled water. The stock solution was split into 4 test tubs and the first tub was used as a control then 1 mL of iron(III) chloride was added to the second tub and 1 mL of potassium thiocyanate was added to the third tub. 0.1 mol/L of silver nitrate was added drop-wise to the forth tub until colour disappears the reactions were observed. Afterwards the solution was split in two and iron (III) chloride drop-wise to one of the test tubs using the other as a comparison. Then In part B of the lab 2-3 mL of potassium chromate was added to a test tub. Then 2 drops of 6 mol/L nitric acid was added and the colour change was noted then 2 mol/L sodium hydroxide was added drop-wise until the original colour was restored. In part C of the experiment 2 mL of cobalt chloride was added in 2 test tubs. 3 mL of concentrated hydrochloric acid 12/mol/L was added drop-wise i...