Mole concept and Stoichiometry

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Class 10 Chemistry Chapter 5
Mole concept and Stoichiometry
Important Questions

Q: Q1 : What does one mole represent?

Ans: A single mole of a substance corresponds to 6.022 × 10^{23} entities, which could be atoms, molecules, or ions. This numerical value, 6.022 × 10^{23}, is referred to as Avogadro’s number or the Avogadro constant. The concept of the mole is valuable for converting between mass and the quantity of particles in chemical substances.

Here, you’ll discover significant inquiries pertaining to Chapter 5: Mole concept and Stoichiometry for ICSE Class 10 Chemistry. These inquiries are carefully designed to aid students in preparing for the ICSE Class 10 Chemistry Examination in 2024–25. Engaging with different question formats allows students to address uncertainties, improve their exam preparedness, boost their self-assurance, and polish their ability to solve problems.

Table of Contents

Introduction

In the ICSE Class 10 Chemistry Chapter 5 on the Mole Concept and Stoichiometry, you will delve into topics like Gay Lussac’s Law of Combining Volumes, the atomicity (number of atoms in a molecule) of hydrogen, oxygen, nitrogen, and chlorine, vapour density, the concept of mole, its connection to mass, and solving problems involving chemical equations. For important questions related to mole concept and stoichiometry class 10 ICSE, you can focus on understanding these concepts thoroughly and practising various types of problems from Oswal.io to excel in your exams.

What is Mole concept and Stoichiometry?

In the ICSE Class 10 Chemistry Chapter 5 titled “Mole Concept and Stoichiometry” The mole concept provides a practical means of representing the quantity of a substance. Any measurement can be dissected into two components: the numerical value and the accompanying measurement units. For instance, when determining the mass of an object as 2 kilograms, ‘2’ represents the numerical magnitude, and ‘kilogram’ represents the units.When working with particles on an atomic or molecular scale, even a single gram of a pure element is recognized to contain an exceedingly large number of atoms. This is where the mole concept comes into play. It primarily revolves around the concept of a ‘mole,’ which signifies a count of an extremely vast number of particles.

Class 10 Chemistry Chapter 5 Mole concept and Stoichiometry Important Questions and Answers

Q1. In $Na_2CO_3$ , percentage mass of oxygen is:

Options

(a) 62.93
(b) 45.3
(c) 59.6
(d) 40.3

Ans. (b) 45.3

Explanation:
The molecular mass of sodium carbonate is 106.
(2Na - 46, 1C = 12, and 3O = 48)
since atomic mass of 3 oxygen atoms is 48
$\text{Therefore 100 }× \dfrac{48}{106} = 45.3%$

Q2. Empirical formula of a substance is $CH_2O.$ Molecular mass is 180. Find its molecular formula.

Options

$(a)\space C_2H_2O_4\\ ‍(b)\space C_2H_4O_6\\ ‍(c)\space C_6H_{12}O_6\\ ‍(d)\space C_2H_4O_8$

Ans. $(C)\space C_6H_{12}O_6$

Explanation:
molar mass of carbon= 12.
molar mass of hydrogen=1.
molar mass of =16.
mass of $CH_2O=12+2(1)+16=30.\\$ molecular wieght of compound given is 180.
so the molecular wieght is
$\dfrac{180}{30} = 6.\\$ ⟹ molecular formula cound is $C_6H_{12}O_6$

Q3. Explain that 1 mole is the amount of a substance containing elementary particles like atoms, molecules or ions in 12g of C.

Explanation:
A mole is the quantity of a substance that contains the same number of particles as present in 12g of Carbon. This is the definition of mole. Here carbon-12 isotope is used as the reference standard because this is the most abundant carbon isotope found on earth. The further extension of this concept of mole is Avogadro's law.

Q4. What is the relationship between gram molecular weight and gram molecular volume at S.T.P. ?

Explanation:
The density of a gas is defined as mass per unit volume. Volume is usually taken as 1 $dm^3$ at S.T.P.Molar volume of hydrogen: Density of hydrogen = 0 09 $gm/dm^3$ at S.T.P. Gram molecular weight of hydrogen = 2.016 g 0.09 g of hydrogen occupies volume = 1 $dm^3$ at S.T.P. 2.016 g of hydrogen occupies volume = $dm^3$ at S.T.P. = 22.4 $dm^3$ at S.T.P. As 2.016 g of hydrogen = 1 gram molecular weight,
∴ 1 gram molecular weight of hydrogen occupies 22.4 $dm^3$ at S.T.P.

Q5. What are the limitations of a chemical equation?

Explanation:

The following are the limitations of the chemical equation:
1. It doesn’t tell us about the physical state of reactants such as solid, liquid, or gaseous.
2. We can’t predict whether an equation is reversible or irreversible.
3. Actual concentration and dilution are unknown.
4. The time duration required for a particular chemical reaction is not known.
5. Whether the reaction goes to completion or is stopped in between i.e., the extent to which a reaction takes place is not known from a chemical equation
6. The parameters that affect a chemical reaction such as temperature, pressure, catalyst, etc are unknown.

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ICSE Class 10 Chemistry Chapter wise Important Questions

Chapter No.	Chapter Name
Chapter 1	Periodic Properties and Variations of Properties
Chapter 2	Chemical Bonding
Chapter 3	Study of Acids, Bases and Salts
Chapter 4	Analytical Chemistry
Chapter 5	Mole concept and Stoichiometry
Chapter 6	Electrolysis
Chapter 7	Metallurgy
Chapter 8	Study of Compounds : Hydrogen Chloride
Chapter 9	Study of Compounds : Ammonia and Nitric Acid
Chapter 10	Study of Compounds : Sulphuric Acid
Chapter 11	Organic Compounds

Conclusion

The study of “Mole Concept and Stoichiometry” in ICSE Class 10 Chemistry has equipped us with a profound understanding of the fundamental principles that underpin chemical calculations and the quantitative aspects of chemistry. This chapter has empowered us to comprehend the essential concept of the mole, enabling us to bridge the gap between the microscopic world of atoms and molecules and the macroscopic realm of chemical reactions.Throughout this chapter, we’ve explored the significance of Avogadro’s number and the mole as a crucial unit for counting atoms and molecules. For those seeking to excel in this vital aspect of chemistry, additional practice and resources are indispensable. Oswal.io offers a comprehensive collection of questions and study materials specifically designed to facilitate your learning process.

Frequently Asked Questions

Q1 : What does one mole represent?

Ans: A single mole of a substance corresponds to

6.022 × 10^{23}

entities, which could be atoms, molecules, or ions. This numerical value,

6.022 × 10^{23},

is referred to as Avogadro’s number or the Avogadro constant. The concept of the mole is valuable for converting between mass and the quantity of particles in chemical substances.

Q2 : What is the significance of the mole concept?

Ans: The mole concept is fundamental in the realm of chemistry, as it underpins virtually all quantitative chemical computations. Therefore, a grasp of the mole concept is crucial for the study of chemistry, especially in its applications to mass and the quantification of entities.

Q3 : What does "mole" represent in chemistry?

Ans: In the field of chemistry, a mole (or abbreviated as “mol”) serves as a standardised scientific measure for dealing with vast quantities of minuscule entities like atoms, molecules, or similar structures.

Q4 : What is the purpose of utilising mole fraction?

Ans: Mole fraction is employed to express the ratio of the number of molecules or moles of a specific component to the total number of molecules or moles within a mixture. It becomes particularly valuable when blending two reactive components because it provides insight into the relative proportions of these components based on their respective mole fractions.

Q5: Is mole fraction equivalent to partial pressure?

Ans: Within a mixture, the partial pressure of each gas corresponds directly to its mole fraction. The pressure exerted individually by each gas, referred to as its partial pressure, remains unaffected by the presence of other gases within the mixture.

Chapter Wise Important Questions for ICSE Board Class 10 Chemistry
Periodic Properties and Variations of Properties
Chemical Bonding
Study of Acids, Bases and Salts
Analytical Chemistry
Mole concept and Stoichiometry
Electrolysis
Metallurgy
Study of Compounds : Hydrogen Chloride
Study of Compounds : Ammonia and Nitric Acid
Study of Compounds : Sulphuric Acid
Organic Compounds

Class 10 Chemistry Chapter 5 Mole concept and Stoichiometry Important Questions

Introduction

What is Mole concept and Stoichiometry?

Class 10 Chemistry Chapter 5 Mole concept and Stoichiometry Important Questions and Answers

Q1. In Na_2CO_3, percentage mass of oxygen is:

Options

(a) 62.93 (b) 45.3 (c) 59.6 (d) 40.3

Q2. Empirical formula of a substance is CH_2O. Molecular mass is 180. Find its molecular formula.

Options

(a)\space C_2H_2O_4\\ ‍(b)\space C_2H_4O_6\\ ‍(c)\space C_6H_{12}O_6\\ ‍(d)\space C_2H_4O_8

Q3. Explain that 1 mole is the amount of a substance containing elementary particles like atoms, molecules or ions in 12g of C.

Q4. What is the relationship between gram molecular weight and gram molecular volume at S.T.P. ?

Q5. What are the limitations of a chemical equation?

ICSE Class 10 Chemistry Chapter wise Important Questions

Conclusion

Frequently Asked Questions

Q1 : What does one mole represent?

Q2 : What is the significance of the mole concept?

Q3 : What does "mole" represent in chemistry?

Q4 : What is the purpose of utilising mole fraction?

Q5: Is mole fraction equivalent to partial pressure?

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Class 10 Chemistry Chapter 5
Mole concept and Stoichiometry
Important Questions

Q1. In $Na_2CO_3$ , percentage mass of oxygen is:

(a) 62.93
(b) 45.3
(c) 59.6
(d) 40.3

Q2. Empirical formula of a substance is $CH_2O.$ Molecular mass is 180. Find its molecular formula.

$(a)\space C_2H_2O_4\\ ‍(b)\space C_2H_4O_6\\ ‍(c)\space C_6H_{12}O_6\\ ‍(d)\space C_2H_4O_8$