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Ch.15 - Chemical Equilibrium
Chapter 15, Problem 7

This reaction is exothermic. C6H12O6(s) + 6 O2(g) ⇌ 6 CO2(g) + 6 H2O(g). Predict the effect (shift right, shift left, or no effect) of increasing and decreasing the reaction temperature. How does the value of the equilibrium constant depend on temperature?

Verified step by step guidance
1
Identify that the reaction is exothermic, meaning it releases heat as a product.
Apply Le Chatelier's Principle, which states that if a system at equilibrium is disturbed, it will shift in a direction that counteracts the disturbance.
Consider the effect of increasing temperature: Since heat is a product in an exothermic reaction, increasing temperature adds more 'product', causing the equilibrium to shift to the left to consume the excess heat.
Consider the effect of decreasing temperature: Removing heat from the system will cause the equilibrium to shift to the right to produce more heat.
Understand that the equilibrium constant (K) for an exothermic reaction decreases with an increase in temperature, as the reaction shifts to the left, and increases with a decrease in temperature, as the reaction shifts to the right.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the system will adjust to counteract the change and restore a new equilibrium. In the context of temperature changes, if the reaction is exothermic, increasing the temperature will shift the equilibrium to the left (toward the reactants), while decreasing the temperature will shift it to the right (toward the products).
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Le Chatelier's Principle

Exothermic Reactions

An exothermic reaction is one that releases heat to the surroundings, resulting in a temperature increase in the environment. In the given reaction, the conversion of glucose and oxygen to carbon dioxide and water releases energy, which is important for predicting how changes in temperature will affect the position of equilibrium and the reaction's behavior.
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Endothermic & Exothermic Reactions

Equilibrium Constant (K)

The equilibrium constant (K) quantifies the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature. The value of K is temperature-dependent; for exothermic reactions, increasing the temperature decreases K, while decreasing the temperature increases K, reflecting the shift in equilibrium position as described by Le Chatelier's Principle.
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Equilibrium Constant K