Grade 11
  1. Basic concepts of chemistry  1.1. Importance of Chemistry  1.2. Nature and scope of chemistry  1.3. laws of chemical combination  1.3.1. Law of conservation of mass  1.3.2. Law of definite proportions  1.3.3. Law of multiple proportions  1.3.4. Law of gaseous volume  1.3.5. Avogadro's Law  1.4. Dalton's atomic theory  1.5. Mole concept and molar mass  1.6. Percent composition  1.7. Empirical and molecular formula  1.8. Stoichiometry and Stoichiometric Calculations  1.9. Limiting reagent concept
  2. Structure of the atom  2.1. Discovery of the electron, proton, and neutron  2.2. Atomic Model  2.2.1. Thomson's model  2.2.2. Rutherford's model  2.2.3. Bohr's model  2.3. Quantum mechanical model of the atom  2.4. Dual nature of matter and radiation  2.5. Heisenberg's uncertainty principle  2.6. Quantum numbers  2.7. Atomic orbitals and their shapes  2.8. Electronic configuration of elements  2.9. Aufbau principle  2.10. Pauli's exclusion principle  2.11. Hund's maximum multiplicity rule  2.12. de Broglie's hypothesis  2.13. Photoelectric effect
  3. Classification of elements and periodicity in properties  3.1. Historical development of the periodic table  3.2. Modern Periodic Law and Periodic Table  3.3. Periodic trends in properties  3.3.1. Atomic and Ionic Radius  3.3.2. Ionization enthalpy  3.3.3. Electron gain enthalpy  3.3.4. Electronegativity  3.3.5. Valency  3.3.6. Metallic and Non-Metallic Properties  3.3.7. Oxidation states  3.4. Unusual Properties of the First Elements
  4. Chemical Bonding and Molecular Structure  4.1. Kossel–Lewis approach to chemical bonding  4.2. Ionic or electrovalent bond  4.3. Covalent bond and its features  4.4. Bond parameters  4.5. VSEPR Theory  4.6. Valence bond theory  4.7. Hybridization and its types  4.8. Molecular orbital theory  4.8.1. Bond order and stability  4.9. Hydrogen bonding
  5. States of matter  5.1. Intermolecular forces  5.2. Gas Laws  5.2.1. Boyle's law  5.2.2. Charles's Law  5.2.3. Avogadro's Law  5.2.4. Dalton's law of partial pressure  5.2.5. Graham's law of spread  5.3. Ideal Gas Equation and Applications  5.4. Real gases and deviations from ideal behaviour  5.5. Kinetic molecular theory of gases  5.6. Liquefaction of gases  5.7. Properties of Liquids  5.8. Surface tension and viscosity
  6. Thermodynamics  6.1. System and environment  6.2. Types of systems in thermodynamics  6.3. Types of procedures  6.4. First law of thermodynamics  6.5. Internal energy and enthalpy  6.6. Heat capacity and specific heat  6.7. Hess's law of constant heat summation  6.8. Bond dissociation enthalpy  6.9. Enthalpy of formation and combustion  6.10. Enthalpy of solution and neutralization  6.11. Spontaneity and the second law of thermodynamics  6.12. Gibbs free energy and its applications
  7. Balance  7.1. The concept of balance  7.2. Equilibrium constant and its applications  7.3. Le Chatelier's principle  7.4. Ionic equilibrium in solutions  7.5. Acid and Base Theory  7.5.1. Arrhenius concept  7.5.2. Bronsted-Lowry concept  7.5.3. Lewis concept  7.6. pH Scale and pOH  7.7. Common ion effect  7.8. Hydrolysis of salts  7.9. Buffer solutions and their mechanism of action  7.10. Solubility equilibrium of sparingly soluble salts
  8. Redox reactions  8.1. Oxidation and reduction concepts  8.2. Oxidation number and its applications  8.3. Redox reactions in terms of electron transfer  8.4. Balancing redox reactions (oxidation number and ion-electron methods)  8.5. Types of redox reactions  8.6. Electrochemical Cells and Redox Reactions
  9. Hydrogen  9.1. Position of Hydrogen in the Periodic Table  9.2. Isotopes of hydrogen  9.3. Preparation of Hydrogen  9.4. Properties of Hydrogen  9.5. Hydrides and their classification  9.6. Water and heavy water  9.7. Hydrogen peroxide and its properties  9.8. Uses of Hydrogen and Its Compounds
  10. S-block elements (alkali and alkaline earth metals)  10.1. Group 1 Elements - Properties and Trends  10.2. Group 2 Elements - Properties and Trends  10.3. Unusual properties of lithium and beryllium  10.4. Important compounds of sodium and their uses  10.5. Important Compounds of Magnesium and Calcium
  11. Some p-block elements  11.1. General Introduction to p-Block Elements  11.2. Group 13 Elements  11.2.1. Boron and its compounds  11.3. Group 14 Elements  11.3.1. Carbon and its allotropes  11.3.2. Important Compounds of Carbon and Silicon
  12. Organic Chemistry - Some Basic Principles and Techniques  12.1. Classification and Nomenclature of Organic Compounds  12.2. Structural representation of organic compounds  12.3. Classification of organic reactions  12.4. Electronic Effects in Organic Chemistry  12.4.1. Inductive effect  12.4.2. Resonance effect  12.4.3. Hyperconjugation  12.5. Reaction mechanism and intermediate species  12.6. Purification and qualitative analysis of organic compounds
  13. Hydrocarbons  13.1. Hydrocarbons  13.1.1. Preparation and Properties of Alkenes  13.2. alkene  13.2.1. Preparation and Properties of Alkenes  13.2.2. Electrophilic addition reactions  13.3. Alkynes  13.3.1. Preparation and Properties of Alkynes  13.4. Aromatic hydrocarbons  13.4.1. Structure and properties of benzene  13.4.2. Electrophilic substitution reactions of benzene
  14. Environmental Chemistry  14.1. Environmental Pollution  14.2. Atmospheric pollution and the greenhouse effect  14.3. Water pollution and treatment methods  14.4. Soil pollution and its effects  14.5. Industrial waste and its treatment  14.6. Strategies for pollution control

Grade 11 → States of matter → Gas Laws ↓


Avogadro's Law


Avogadro's law is one of the fundamental principles underlying the gas laws in chemistry. It states that at constant temperature and pressure, the volume of a gas is directly proportional to the number of moles of gas. This implies that if you change the amount of gas in a container, the volume will change as long as the temperature and pressure remain constant.

Avogadro's law formula

The mathematical expression of Avogadro's law is as follows:

V ∝ n

This can be further expressed as:

V = k × n

Where:

  • V is the volume of the gas.
  • n is the number of moles of the gas.
  • k is a proportionality constant.

If you have two different states of a gas, you can express this relationship like this:

V1 / n1 = V2 / n2

Where:

  • V1 and V2 are the initial and final volumes of the gas, respectively.
  • n1 and n2 are the initial and final moles of the gas, respectively.

Visual example

Let us imagine that we have a flexible balloon filled with a certain amount of gas. If we increase the number of moles of gas in the balloon while keeping the temperature and pressure constant, the volume of the balloon will also increase. This is simply because there are more gas particles that require more space to exist.

Lower Mole High moles

Practical example

Let's consider an example of how Avogadro's law can be used in a practical situation:

Imagine that we have a container with 2 moles of nitrogen gas in a volume of 10 liters. Suppose we add 2 more moles of nitrogen gas to the container, keeping the temperature and pressure constant, making a total of 4 moles. What will be the new volume of the gas?

Using Avogadro's law, we can formulate the following equation:

V1 / n1 = V2 / n2

Substituting the known values, we get:

10 L / 2 moles = V2 / 4 moles

Solving for V2, we get:

V2 = (10 L * 4 moles) / 2 moles V2 = 20 L

This calculation shows that by doubling the amount of gas in the container, the volume also doubles to 20 liters.

Another visual example

Consider a piston cylinder into which a certain amount of gas has been added. As you add more gas to the cylinder, you will see a direct increase in the height of the piston, provided that the pressure and temperature remain constant.

Lower Mole High moles

More examples and applications

In real-world applications, Avogadro's Law is extremely useful in chemical industry processes where gas volumes need to be accurately calculated. For example, when manufacturing products that require specific amounts of gases such as oxygen or hydrogen, Avogadro's Law is used to determine how much space is needed or what the volume of a container should be to hold a certain number of moles of gas.

Examples of breathing

The human lungs essentially follow Avogadro's law. When you inhale, the diaphragm expands, making more room in the lungs. This allows more gas (air) to flow in, increasing the volume. When you exhale, the volume within the lungs decreases as the diaphragm contracts, allowing air to escape.

The increase and decrease in the number of air molecules, and consequently, the amount the lungs can hold, is a biological example of Avogadro's law in action.

Theoretical basis

The theoretical basis of Avogadro's law stems from the nature of gases. According to the kinetic molecular theory, gases are composed of widely spaced molecules in constant, random motion. This theory supports the notion that the volume of a gas depends on the amount of gas molecules, not on their identity or mass.

Understanding the importance

Understanding Avogadro's law helps chemists and educators explain how gases behave on a microscopic scale and predict their behavior in macroscopic applications. This understanding forms the basis for more advanced studies and applications in thermodynamics, fluid dynamics, and various engineering disciplines.

Key takeaways

  • Avogadro's law states that the volume of a gas is directly proportional to the number of moles when temperature and pressure are constant.
  • Its mathematical form is V ∝ n or V1 / n1 = V2 / n2.
  • This law is fundamental in calculations involving gas mixtures and chemical reactions where gases are involved.
  • Practical examples of this law include the behavior of gases in balloons, syringes, cylinders, and even human lungs during breathing.

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Avogadro's Law

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