Grade 10
  1. Matter and its properties  1.1. States of matter  1.2. Physical and chemical properties of matter  1.3. Classification of substances (elements, compounds, mixtures)  1.4. Changes in Matter (Physical and Chemical Changes)  1.5. Law of conservation of mass and law of definite proportions
  2. Atomic Structure  2.1. Historical development of the atomic model  2.2. Subatomic particles (protons, neutrons, electrons)  2.3. Atomic number, mass number and isotopes  2.4. Electronic Configuration and Energy Levels  2.5. Valency, ion formation and oxidation state
  3. Periodic table  3.1. History and Development of the Periodic Table  3.2. Modern Periodic Law and Periodic Trends  3.3. Groups and Periods in the Periodic Table  3.4. Trends in the Periodic Table  3.5. Metals, non-metals, metalloids and their properties  3.6. Noble gases and their chemical inertness
  4. Chemical bond  4.1. Formation of Chemical Bonds (Octet Rule)  4.2. Ionic Bonding and Properties of Ionic Compounds  4.3. Covalent Bond and Properties of Covalent Compounds  4.4. Metallic bond and its properties  4.5. Molecular geometry and VSEPR theory  4.6. Polarity and dipole moment of molecules  4.7. Intermolecular forces
  5. Chemical Reactions and Equations  5.1. Types of Chemical Reactions  5.2. Writing and balancing chemical equations  5.3. Law of conservation of mass in chemical reactions  5.4. Factors Affecting Chemical Reactions  5.5. Catalysts and their role in chemical reactions  5.6. Exothermic and Endothermic Reactions
  6. Stoichiometry and Chemical Calculations  6.1. Mole concept and Avogadro number  6.2. Molar Mass and Gram-Mole Conversions  6.3. Empirical and molecular formula  6.4. Stoichiometric calculations and chemical yield  6.5. Limiting and Excess Reactants
  7. Acids, Bases and Salts  7.1. Properties and Definitions of Acids and Bases (Arrhenius, Bronsted-Lowry, Lewis)  7.2. pH Scale, pOH, and Indicators  7.3. Neutralization reactions and salt formation  7.4. Strength of Acids and Bases (Strong vs. Weak Acids and Bases)  7.5. Common Acids and Bases in Daily Life  7.6. Salts, their solubility and applications
  8. Metals and Nonmetals  8.1. Physical and chemical properties of metals  8.2. Physical and Chemical Properties of Non-Metals  8.3. Reactivity Series of Metals and Displacement Reactions  8.4. Extraction of metals from ores  8.5. Corrosion, its causes and prevention  8.6. Alloys, their composition and uses
  9. Carbon and its compounds  9.1. Allotropes of Carbon  9.2. Hydrocarbons and their classification (alkanes, alkenes, alkynes)  9.3. Functional groups in organic compounds  9.4. Nomenclature of organic compounds (IUPAC system)  9.5. Isomerism in organic chemistry (structural and geometrical)  9.6. Important organic reactions (combustion, addition, substitution, polymerization)  9.7. Applications of organic compounds in industry and daily life
  10. Environmental Chemistry  10.1. Air Pollution (Sources, Effects and Control)  10.2. Water Pollution (Causes, Effects and Remedies)  10.3. Greenhouse effect and global warming  10.4. Ozone layer depletion and its effects  10.5. Green Chemistry and Its Applications  10.6. sustainable chemistry practice
  11. Thermochemistry  11.1. Heat and Energy Changes in Chemical Reactions  11.2. Exothermic and Endothermic Reactions  11.3. Enthalpy, enthalpy change, and heat of reaction  11.4. Specific heat capacity and calorimetry  11.5. Energy Changes in Combustion Reactions
  12. Electrochemistry  12.1. Electrolytes and non-electrolytes  12.2. Electrolysis and its applications (electroplating, extraction of metals)  12.3. Redox reactions (oxidation and reduction)  12.4. Galvanic cell and electrochemical series  12.5. Corrosion and electrochemical prevention methods
  13. Chemical kinetics and equilibrium  13.1. Rate of chemical reactions and its measurement  13.2. Factors affecting the reaction rate (catalyst, temperature, concentration)  13.3. Reversible and irreversible reactions  13.4. Dynamic equilibrium and equilibrium constant  13.5. Le Chatelier's principle and its applications
  14. Gases and Gas Laws  14.1. Properties of gases and kinetic molecular theory  14.2. Boyle's Law (Pressure-Volume Relation)  14.3. Charles's Law  14.4. Gay-Lussac's Law  14.5. Combined Gas Law and Ideal Gas Law  14.6. Real Gases vs Ideal Gases
  15. Nuclear Chemistry  15.1. Introduction to Radioactivity and Nuclear Reactions  15.2. Types of radioactive decay (alpha, beta, gamma)  15.3. Half-life and applications of radioactive isotopes  15.4. Nuclear fission and fusion reactions  15.5. Nuclear power generation and its environmental impact

Grade 10 → Chemical kinetics and equilibrium ↓


Le Chatelier's principle and its applications


In chemistry, reactions can often be seen as dancing on the edge of change. Just as tightrope walkers strive for balance, so do chemical reactions. When the conditions around them change, reactions wobble and shift to regain stability. This balancing act in chemistry is explained by Le Chatelier's principle, named after the French chemist Henri Louis Le Chatelier. It plays a central role in understanding chemical kinetics and equilibrium.

Basics of chemical equilibrium

Before we dive into Le Chatelier's principle, let's talk about chemical equilibrium, which is a key point in reactions. In many reactions, products and reactants constantly dance back and forth. In the beginning, when the reactants form products, we see the reaction proceeding in the forward direction. Over time, some of these products turn back into the reactants, creating a backward reaction.

Chemical equilibrium is achieved when the forward and reverse reactions occur at the same rate. At this point, the concentrations of the reactants and products remain unchanged. This does not mean that the reaction stops. Instead, both reactions continue to occur, but there is no net change in the concentrations of the reactants and products over time.

Understanding Le Chatelier's principle

Le Chatelier's principle is a simple but profound idea that helps us predict how changes in conditions affect chemical equilibrium. The principle states:

If a change in conditions causes a disturbance in the dynamic equilibrium, the equilibrium position shifts, thereby counteracting the change and establishing a new equilibrium.

This theory helps in predicting the direction in which the equilibrium will shift if any of the following changes occur:

  • Changes in concentration
  • Changes in temperature
  • Changes in pressure
  • Catalyst addition

Visualizing equilibrium changes

Let us understand this concept using a simple chemical equation:

A + B ⇌ C + D
A+B C+D Ahead Backward

Changes in concentrations

The first factor to consider is concentration. Imagine if we increase the concentration of reactant A According to Le Chatelier's principle, the system will try to minimize this change by shifting the equilibrium to the right, leading to the formation of more products. This helps eliminate the excess A

Conversely, if C is removed, the system will shift to the right and produce more C and D, trying to replace what was removed.

Changing temperatures

Changes in temperature can also have a profound effect on reactions. Consider an exothermic reaction, where heat is released:

A + B ⇌ C + D + Heat

If we increase the temperature, the system will act as if heat is a reactant, shifting the equilibrium to the left to absorb the extra heat and thus promoting the opposite reaction. A decrease in temperature, on the contrary, promotes the forward reaction, as the system seeks to produce more heat.

Pressure effect

Pressure mainly affects reactions involving gases. If we examine the reaction:

2A(g) + B(g) ⇌ 3C(g)

Increasing the pressure shifts the equilibrium to the side where there are fewer moles of gas. In this case, if the pressure is increased, the reaction moves to the left, causing the volume to decrease. Decreasing the pressure will shift it to the right.

Role of catalysts

Catalysts speed up reactions but do not change the equilibrium concentrations. They lower the activation energy for both the forward and backward reactions equally, causing the system to reach equilibrium faster.

Practical applications of Le Chatelier's principle

Industrial processes

Le Châtelier's principle is used extensively to maximize yield in industrial chemical processes.

Haber process

The Haber process to make ammonia is a prime example. The equation for this reaction is:

N 2 (g) + 3H 2 (g) ⇌ 2NH 3 (g)
N 2 + 3H 2 2NH 3 Ahead Backward

Since ammonia production is exothermic, lower temperatures would be favorable for greater production. However, low temperatures slow the reaction. A compromise is achieved by using high pressure and moderate temperatures with a catalyst to speed up the reaction.

Contact process

Another important process is the contact process which is used to make sulfuric acid:

2SO 2 (g) + O 2 (g) ⇌ 2SO 3 (g)

High pressure promotes the formation of SO 3, while high temperature would favor the opposite of the reaction because it is exothermic. Again, the equilibrium is reached by operating at the optimum temperature and using a vanadium(V) oxide catalyst.

Conclusion

Le Chatelier's principle is a powerful tool in the chemist's toolkit. By understanding how changes in concentration, temperature, pressure, and the presence of catalysts affect the equilibrium position, chemists can better control reactions to improve yields or prevent unwanted side reactions. This principle not only helps in industrial applications but it also deepens our understanding of how reactions naturally tend toward equilibrium.

Through Le Chatelier’s lens, we see a dynamic world of chemical reactions, a harmony constantly redefined by external factors striving for balance.


Grade 10 → 13.5


U
username
0%
completed in Grade 10

← Prev (13.4)
Dynamic equilibrium and equilibrium constant
Next (14) →
Gases and Gas Laws

Comments 



Le Chatelier's principle and its applications

https://www.chemistryelite.com/g10/13.5?ceal=en