The Dynamic Dance: Reversible Reactions and Le Chatelier's Principle

• Chemistry
• Upper Secondary (Key Stage 4)
• GCSE

The Dynamic Dance: Reversible Reactions and Le Chatelier's Principle

Learning Objective

At the end of the lesson, you will be able to understand and apply the concepts of reversible reactions, equilibrium, and Le Chatelier's Principle.

What do you already know about reversible reactions and equilibrium?

Slide 1: Introduction

Reversible reactions are chemical reactions that can proceed in both forward and reverse directions. Equilibrium is a state where the concentrations of reactants and products remain constant. Le Chatelier's Principle helps us predict how equilibrium will shift when a change is made to the system.

Slide 2: Characteristics of Reversible Reactions

Reversible reactions are indicated by a double arrow (↔) in chemical equations. They can occur in both directions, with reactants converting into products and products converting back into reactants.

Slide 3: Dynamic Equilibrium

Dynamic equilibrium is a state where the rate of the forward reaction is equal to the rate of the reverse reaction. In this state, the concentrations of reactants and products remain constant over time.

Slide 4: Factors That Affect Equilibrium

Equilibrium can be affected by changes in temperature, pressure, and concentration. Adding or removing reactants or products can shift the equilibrium position.

What factors can affect the position of equilibrium?

1. Temperature, pressure, and concentration
2. Time, volume, and mass
3. Density, viscosity, and pH
4. Color, odor, and texture

What happens to the concentration of reactants and products at equilibrium?

1. The concentrations increase over time
2. The concentrations decrease over time
3. The concentrations fluctuate randomly
4. The concentrations remain constant

What is equilibrium in a chemical reaction?

1. A state in which the reaction proceeds very slowly
2. A state in which the reaction stops completely
3. A state in which only the forward reaction occurs
4. A state in which the forward and reverse reactions occur at the same rate

What is a reversible reaction?

1. A reaction that only proceeds in one direction
2. A reaction that produces a lot of heat
3. A reaction that involves two elements
4. A reaction that can proceed in both directions

Slide 5: Le Chatelier's Principle

Le Chatelier's Principle states that when a system at equilibrium is subjected to a change, it will adjust itself to counteract the effect of that change. It helps us predict how the equilibrium will shift.

Slide 6: Effect of Temperature Changes

Increasing the temperature of an exothermic reaction shifts the equilibrium towards the left, favoring the reactants. Decreasing the temperature has the opposite effect.

Slide 7: Effect of Pressure Changes

Increasing the pressure in a system with fewer moles of gas will shift the equilibrium towards the side with fewer gas molecules. Decreasing the pressure has the opposite effect.

Slide 8: Effect of Concentration Changes

Increasing the concentration of a reactant or product shifts the equilibrium away from that substance. Decreasing the concentration has the opposite effect.

Slide 9: Catalysts and Equilibrium

Catalysts do not affect the position of equilibrium but can increase the rate at which equilibrium is reached. They provide an alternative reaction pathway with a lower activation energy.

Complete the Worksheet on Google Classroom as we go through the simulation

How does an increase in temperature affect an exothermic reaction at equilibrium?

1. The system will shift to the left, favoring the reactants.
2. The temperature has no effect on the system.
3. The reaction will stop.
4. The system will shift to the right, favoring the products.

What will happen if the pressure is increased in a system at equilibrium with fewer moles of gas on the reactant side?

1. The system will shift to the side with more moles of gas.
2. The system will remain at equilibrium.
3. The system will shift to the side with fewer moles of gas.
4. The pressure has no effect on the system.

If the concentration of reactants in a system at equilibrium is increased, what will happen?

1. The system will stop reacting.
2. The system will shift to form more reactants.
3. The system will remain at equilibrium.
4. The system will shift to form more products.

Which factor does Le Chatelier's principle consider when predicting the direction of a shift?

1. Pressure
2. Volume
3. Temperature
4. Concentration

What does Le Chatelier's principle state?

1. A system at equilibrium will respond to a stress by shifting to counteract the stress.
2. A system at equilibrium will respond to a stress by accelerating the reaction.
3. A system at equilibrium will respond to a stress by maintaining equilibrium.
4. A system at equilibrium will respond to a stress by ignoring the stress.

Exam question time! Complete the practice exam questions in the booklet