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 → Electrochemistry ↓


Corrosion and electrochemical prevention methods


Corrosion is an important topic in the study of chemistry, particularly electrochemistry, especially when discussing the implications of chemical reactions over time. This lesson will guide you through the fundamentals of corrosion, its electrochemical nature, how it occurs naturally, and methods used to prevent or minimize its effects. We will make sure to break down complex concepts into simple terms for better understanding.

What is corrosion?

Corrosion is a natural process that slowly destroys substances, usually metals, through chemical or electrochemical reactions with their environment. The most common example is the rusting of iron. Imagine a piece of iron left exposed to the rain; over time, it discolours and becomes weaker - this is called rust.

Chemically, corrosion can be understood as an oxidation reaction in which metal atoms lose electrons to become metal ions. A classic example of such a reaction is when iron reacts with oxygen in the presence of water:

4Fe + 3O 2 + 6H 2 O → 4Fe(OH) 3

The product, iron(III) hydroxide, further reacts with oxygen to form hydrated iron(III) oxide, which is rust.

Electrochemical nature of corrosion

Corrosion is not just a chemical reaction, but an electrochemical process. Let's break it down into steps to understand how electrochemistry plays a role in corrosion.

Step 1: Anodic reaction

At the anode, iron loses electrons and dissolves in water to form ferrous ions:

Fe → Fe 2+ + 2e -

Step 2: Cathodic reaction

The released electrons move to the cathode region, where the reduction reaction takes place. Typically, oxygen in the presence of water acts as an oxidizing agent:

O 2 + 4e - + 2H 2 O → 4OH -

Overall response

Combining both anodic and cathodic reactions, we get the overall corrosion reaction. The metal is oxidized at the anode, while the nonmetal is reduced at the cathode:

2Fe + O 2 + 4H 2 O → 2Fe(OH) 2

A simplified electrochemical cell can be used to demonstrate this process.

FeO2AnodeCathode

Factors affecting corrosion

Several factors affect the rate and extent of corrosion, including:

  • Nature of metal: Metals such as iron corrode more easily than metals such as gold or platinum.
  • Environment: Moist and oxygen-rich environments promote rapid corrosion.
  • Presence of electrolytes: Substances such as salt accelerate the corrosion process.
  • Temperature: Higher temperatures generally increase the rate of corrosion.

Rust prevention

Although corrosion is inevitable for some materials, various electrochemical methods can be used to slow or stop corrosion.

1. Coating on metal surface

One of the simplest methods is to apply a coating to the metal to protect it from direct contact with a corrosive environment. Common coatings include paint, plastic, or applying a layer of metal such as zinc or chromium, known as galvanization.

2. Cathodic protection

In this method, the metal to be protected is made the cathode of an electrochemical cell. A more easily corroded "sacrificial anode" (such as zinc or magnesium) is placed in direct contact with the metal. The sacrificial anode corrodes instead of the protected metal. This method is widely used in pipelines and ships.

A common example of cathodic protection is the prevention of corrosion in underground pipelines:

PipeSacrificial Anode

3. Anodic protection

Anodic protection is the opposite of cathodic protection. In this method, the metal to be protected is made the anode. This is achieved by connecting the metal to a more noble metal in the electrochemical series or by using an external direct current power source. This method is suitable for metals such as stainless steel in environments such as acid plants.

Electrochemical methods in real life

There are many examples where electrochemical methods prevent corrosion in daily life:

  • Automobiles: Galvanization is often used in cars to prevent them from rusting.
  • Structural steel: Electrochemical protection is used to maintain integrity in large buildings.
  • Marine industry: Ships and submarines are protected from corrosion through sacrificial anodes.

Conclusion

Corrosion is a continuing challenge in preserving the life of metal structures and objects. It is important to understand its electrochemical nature and adopt appropriate prevention techniques. The methods discussed provide valuable information on how to manage corrosion, thereby extending the life and service of metal products.

By incorporating coatings, cathodic and anodic protection, we can reduce the harmful effects of corrosion, leading to better use of materials and greater sustainability in various aspects of human life.


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