Lesson List
CHAPTER 3: CLASSIFICATION OF ELEMENTS
Section Name Topic Name 3 Classification of Elements and Periodicity in Properties 3.1 Why do we Need to Classify Elements ? 3.2 Genesis of Periodic Classification 3.3 Modern Periodic Law and the present form of the Periodic Table 3.4 Nomenclature of Elements with Atomic Numbers > 100 3.5 Electronic Configurations of Elements and the Periodic Table 3.6 Electronic Configurations and Types of Elements: s-, p-, d-, f – Blocks 3.7 Periodic Trends in Properties of Elements
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CHAPTER 7: EQUILIBRIUM
Section Name Topic Name 7 Equilibrium 7.1 Equilibrium in Physical Processes 7.2 Equilibrium in Chemical Processes – Dynamic Equilibrium 7.3 Law of Chemical Equilibrium and Equilibrium Constant 7.4 Homogeneous Equilibria 7.5 Heterogeneous Equilibria 7.6 Applications of Equilibrium Constants 7.7 Relationship between Equilibrium Constant K, Reaction Quotient Q and Gibbs Energy G 7.8 Factors Affecting Equilibria 7.9 Ionic Equilibrium in Solution 7.10 Acids, Bases and Salts 7.11 Ionization of Acids and Bases 7.12 Buffer Solutions 7.13 Solubility Equilibria of Sparingly Soluble Salts
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CHAPTER 10: S-BLOCK ELEMENTS
Section Name Topic Name 10 The s-Block Elements 10.1 Group 1 Elements: Alkali Metals 10.2 General Characteristics of the Compounds of the Alkali Metals 10.3 Anomalous Properties of Lithium 10.4 Some Important Compounds of Sodium 10.5 Biological Importance of Sodium and Potassium 10.6 Group 2 Elements : Alkaline Earth Metals 10.7 General Characteristics of Compounds of the Alkaline Earth Metals 10.8 Anomalous Behaviour of Beryllium 10.9 Some Important Compounds of Calcium 10.10 Biological Importance of Magnesium and Calcium
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CHAPTER 12: CHARACTERIZATION OF ORGANIC COMPOUND
Section Name Topic Name 12 Organic Chemistry – Some Basic Principles and Techniques 12.1 General Introduction 12.2 Tetravalence of Carbon: Shapes of Organic Compounds 12.3 Structural Representations of Organic Compounds 12.4 Classification of Organic Compounds 12.5 Nomenclature of Organic Compounds 12.6 Isomerism 12.7 Fundamental Concepts in Organic Reaction Mechanism 12.8 Methods of Purification of Organic Compounds 12.9 Qualitative Analysis of Organic Compounds 12.10 Quantitative Analysis
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Lesson: Avogadro Law || Ideal Gas Equation || Density and Molar Mass of a Gaseous Substance
About Lesson

Avogadro Law

  • It states that equal volumes of all gases under the same conditions of temperature and pressure
    contain equal number of molecules. Mathematically,

Ideal Gas Equation

  • The gases following Boyle’s law, Charles’law and Avogadro law firmly are termed as anideal gas.
  • From Boyle’s law we have  V ∝ 1/p (Constant T, n)
  • From Charles’ law we have  V ∝ T (Constant p, n)
  • From Avogadro’s law we have V ∝ n (Constant T, n)
  • Combining them we get,  V ∝ nT/p
  • or V = nRT/p 

pV = nRT ………………………… (IDEAL GAS EQUATION)

R =pV/nT

R= Gas Constant. It is same for all gases.

Problem:

Using the equation of state pV = nRT; show that at a given temperature density of a gas is proportional to gas pressure.

Solution:

Using Ideal gas equation, pV = nRT ……….. (1)

p → Pressure of gas

V → Volume of gas

n→ Number of moles of gas

R → Gas constant

T → Temperature of gas

From equation (1),

p = n RT/V

n = Mass of Gas (m) /Molar Mass of gas (M)

Putting value of n in the equation, we have

 p = m RT/ MV ————(2)

Density (ρ) = m /V —————-(3)

Putting (3) in (2) we get

p = ρ RT / M

Or ρ = PM / RT

Problem:

Calculate the total pressure in a mixture of 8 g of dioxygen and 4 g of dihydrogen confined in a vessel of 1 dm3 at 27°C. R = 0.083 bar dm3 K–1 mol–1.

Solution:

m (Oxygen) = 8 g,

M (Oxygen) = 32 g/mol

m ( Hydrogen) = 4 g,

M (Hydrogen) = 2 g/mol

n (Amount of oxygen) = 8/ 32 = 0.25 mol

n (Amount of hydrogen) = 4/2 = 2 mol

According to ideal gas equation,  

PV = n RT,

 P X 1 = (0.25 + 2) X 0.083 X 300 = 56.02 bar

Total pressure of the mixture is 56.02 bars.

Problem:

Calculate the volume occupied by 8.8 g of CO2 at 31.1°C and 1 bar pressure. R = 0.083 bar L K–1 mol-1.

Solution:

According to ideal gas equation, PV = nRT

But n = Mass of Gas (m)/ Molar mass of Gas (M)

PV = (m/M) RT

For CO2 , M = 44 g/mol

Putting the values

1 x V = (8.8 / 44) x 0.083 x 304.1

 = 5.05 L

Volume occupied is 5.05 L.

Density and Molar Mass of a Gaseous Substance

  • As per ideal gas equation,

pV = nRT

Or n/V = p/RT

  • As we know n = Mass of Gas (m) / Molar Mass of Gas (M) = m/M

So, m/MV = p/RT

d/M= p/RT

  • Or Molar mass = M = dRT/p

Problem:

At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?

Solution:

Using the formula  ρ = Mp/RT

or p = ρ RT/ M

According to the question,

For certain oxide gas

2 = ρ RT/ M ……………(1)

For nitrogen

5 = ρ RT/28 ………………….(2)

From equation (1) & (2), we get

5/2 = M/28

Or

M = 5 X 28/ 2 = 70g/mol

Problem:

Density of a gas is found to be 5.46 g/dm3 at 27 °C at 2 bar pressure. What will be its density at STP?

Solution:

According to the ideal gas

Density ρ = p x M/ RT

According to the question,

5.46 = 2 x M/ 300 x R    ……… (1)

ρSTP = 1 x M/ 273 x R    ……….. (2)

From equation (1) & (2),

ρSTP =  (1 x M/ 273 x R)   x (300 x R/ 2 x M) = 300 / 273 X 2 = 3.00 g/dm3

Density of the gas at STP will be 3 g dm–3.

Problem:

Calculate the total number of electrons present in 1.4 g of dinitrogen gas.

Solution:

m ( Nitrogen) = 1.4 g

M (Nitrogen) = 28 g mol–1

n (Amount of nitrogen) = 1.4 / 28 = 0.05 mol

Hence number of nitrogen molecule in 0.05 mol = 6.023 x 1023  x 0.05 = 3.0115 x 1022

Number of electrons in one molecule of nitrogen = 14

Total number of electrons in 1.4 g of nitrogen = 3.0115 x 1022 x 14  = 4.22 x 1023

 

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Lesson List
CHAPTER 3: CLASSIFICATION OF ELEMENTS
Section Name Topic Name 3 Classification of Elements and Periodicity in Properties 3.1 Why do we Need to Classify Elements ? 3.2 Genesis of Periodic Classification 3.3 Modern Periodic Law and the present form of the Periodic Table 3.4 Nomenclature of Elements with Atomic Numbers > 100 3.5 Electronic Configurations of Elements and the Periodic Table 3.6 Electronic Configurations and Types of Elements: s-, p-, d-, f – Blocks 3.7 Periodic Trends in Properties of Elements
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CHAPTER 7: EQUILIBRIUM
Section Name Topic Name 7 Equilibrium 7.1 Equilibrium in Physical Processes 7.2 Equilibrium in Chemical Processes – Dynamic Equilibrium 7.3 Law of Chemical Equilibrium and Equilibrium Constant 7.4 Homogeneous Equilibria 7.5 Heterogeneous Equilibria 7.6 Applications of Equilibrium Constants 7.7 Relationship between Equilibrium Constant K, Reaction Quotient Q and Gibbs Energy G 7.8 Factors Affecting Equilibria 7.9 Ionic Equilibrium in Solution 7.10 Acids, Bases and Salts 7.11 Ionization of Acids and Bases 7.12 Buffer Solutions 7.13 Solubility Equilibria of Sparingly Soluble Salts
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CHAPTER 10: S-BLOCK ELEMENTS
Section Name Topic Name 10 The s-Block Elements 10.1 Group 1 Elements: Alkali Metals 10.2 General Characteristics of the Compounds of the Alkali Metals 10.3 Anomalous Properties of Lithium 10.4 Some Important Compounds of Sodium 10.5 Biological Importance of Sodium and Potassium 10.6 Group 2 Elements : Alkaline Earth Metals 10.7 General Characteristics of Compounds of the Alkaline Earth Metals 10.8 Anomalous Behaviour of Beryllium 10.9 Some Important Compounds of Calcium 10.10 Biological Importance of Magnesium and Calcium
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CHAPTER 12: CHARACTERIZATION OF ORGANIC COMPOUND
Section Name Topic Name 12 Organic Chemistry – Some Basic Principles and Techniques 12.1 General Introduction 12.2 Tetravalence of Carbon: Shapes of Organic Compounds 12.3 Structural Representations of Organic Compounds 12.4 Classification of Organic Compounds 12.5 Nomenclature of Organic Compounds 12.6 Isomerism 12.7 Fundamental Concepts in Organic Reaction Mechanism 12.8 Methods of Purification of Organic Compounds 12.9 Qualitative Analysis of Organic Compounds 12.10 Quantitative Analysis
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