Free Le Chatelier's Principle Lesson

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Lesson 1: Le Chatelier's Principle

Le Chatelier's Principle

Le Chatelier's Principle states that if a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the system will adjust itself to counte\fract that change and establish a new equilibrium.

Key Concepts

Equilibrium: A state where the rates of the forward and reverse reactions are equal.
Dynamic Nature: Even at equilibrium, reactions continue to occur, but there is no net change in concentrations.
Stress Factors: Changes in concentration, temperature, or pressure that can shift the position of equilibrium.

Mathematical Representation

For a general reaction: ${aA} + bB \rightleftharpoons cC + {dD}$ The equilibrium constant, $_{}$ , is given by:

Keywords: Le Chatelier's Principle, equilibrium, stress factors, concentration, temperature, pressure

Next Page: Lesson 2

Lesson 2: Le Chatelier's Principle

What happens to the equilibrium when the temperature is increased in an exothermic reaction?
How does a change in pressure influence gaseous equilibria?

Summary

Le Chatelier's Principle provides a framework for predicting how changes in conditions affect chemical equilibria, allowing chemists to manipulate reactions for desired outcomes.

Keywords: Le Chatelier's Principle, equilibrium, stress factors, concentration, temperature, pressure

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K_{c}

K_c = \frac{[C]^c[D]^d}{[A]^a[B]^b}

Effects of Changes

Change in Concentration:
- Adding a reactant shifts equilibrium to the right (producing more products).
- Removing a product shifts equilibrium to the left (producing more reactants).
Change in Temperature:
- For an exothermic reaction, increasing the temperature shifts equilibrium to the left (favoring reactants).
- For an endothermic reaction, increasing the temperature shifts equilibrium to the right (favoring products).
Change in Pressure:
- Increasing the pressure shifts equilibrium towards the side with fewer moles of gas.
- Decreasing the pressure shifts equilibrium towards the side with more moles of gas.

Example

Consider the equilibrium reaction: ${N}_{2}(g) + 3 {H}_{2}(g) \rightleftharpoons 2 {NH}_{3}(g)$

If we increase the concentration of ${H}_{2}$ , the system will shift to the right to produce more ${NH}_{3}$ .
If we decrease the temperature of an exothermic reaction, it will also shift to the right to produce more products.

Key Questions

How does changing the concentration of reactants affect the position of equilibrium?