Chemistry | Chemical equilibrium | Le Chartelie's Principle

The video begins with a greeting and an introduction to the topic of chemical equilibrium. The presenter explains that chemical equilibrium is a state where the rate of the forward reaction equals the rate of the reverse reaction. They also introduce the factors that affect chemical equilibrium: concentration, temperature, and pressure. The presenter emphasizes the importance of understanding how these factors influence equilibrium and introduces Le Chatelier's principle, which states that if a change is applied to a system at equilibrium, the system will adjust to counteract the change and establish a new equilibrium.

The presenter uses a seesaw model to illustrate Le Chatelier's principle. They describe a scenario where adding more weight (or 'children') to one side of the seesaw (representing an increase in concentration) causes an imbalance. To restore equilibrium, a large ball (representing the system's response) is moved to the opposite side. This model is used to show that when a system at equilibrium is disturbed, it will shift to counteract the disturbance. The video also clarifies that catalysts and surface area are not included in this discussion because they affect different types of reactions and do not disturb chemical equilibrium in closed systems.

The video discusses how changes in the concentration of reactants or products affect the equilibrium of a closed system. It uses the example of the reaction between nitrogen and hydrogen to form ammonia. The presenter explains that adding more nitrogen will disturb the equilibrium, causing the system to shift towards the right to consume the added nitrogen, thereby increasing the amount of ammonia produced. Conversely, removing nitrogen from the system will cause the equilibrium to shift to the left, favoring the reverse reaction and decreasing the amount of ammonia.

The presenter explains the impact of temperature on chemical equilibrium, differentiating between endothermic and exothermic reactions. They use the mnemonic of Pac-Man to help remember that an increase in temperature favors the endothermic reaction (where heat is on the right side of the reaction), and a decrease in temperature favors the exothermic reaction. The video provides an example of how increasing temperature affects the yield in an exothermic reaction, causing the equilibrium to shift to the left and decrease the amount of products formed.

The video addresses how pressure affects the equilibrium of gaseous reactions. It explains that pressure changes only impact the equilibrium if there is a difference in the number of moles of gas between reactants and products. An increase in pressure favors the side with fewer moles of gas, while a decrease in pressure favors the side with more moles of gas. The presenter uses the example of the reaction between nitrogen and hydrogen to form ammonia, illustrating that increasing pressure would shift the equilibrium to the right, increasing the amount of ammonia produced.

The presenter concludes the video by summarizing the application of Le Chatelier's principle to the three factors affecting equilibrium: concentration, temperature, and pressure. They remind viewers that these factors only affect gases and aqueous solutions, not solids or liquids. The video promises to show how these concepts are applied in exam situations in a future video. The presenter encourages viewers to ask questions or provide feedback via email and to comment on the video if they found the illustrations helpful.