Some Basic Concepts of Chemistry - Notes, Topics, Formula, Books, FAQs

Some Basic Concepts of Chemistry - Notes, Topics, Formula, Books, FAQs

Edited By Team Careers360 | Updated on Nov 21, 2024 09:42 AM IST

'Some basic concepts of chemistry' is the most fundamental chapter of complete chemistry. It gives information about the atomic number and mass number of elements. In any chemical reaction, it is important for us to know about the amount and number of reactants that will consume and the products that will produce, thus for estimating all these calculations, we use the laws of chemical combinations.

Notes for Some Basic Concepts in Chemistry


In this section, you will study about the important topics of the chapter, overview, formulae and some important tips and guidelines for the preparation of the chapter at the best.

Important Topics

Nature of Matter

  • Matter is anything that occupies space and has mass. It exists in three physical states—solid, liquid, and gas and can undergo physical or chemical changes based on its properties. Understanding nature of matter is inevitable to decipher the mechanisms of various chemical reactions.

Laws of Chemical Combination

  • Laws of chemical combination are fundamental principles governing chemical reactions, including the Law of Conservation of Mass and the Law of Definite Proportions, which describe the behaviour of matter during chemical changes.

Dalton's Atomic Theory

  • Daltons Atomic Theory was proposed in 1808, this theory states that all matter is composed of indivisible atoms, which combine in fixed whole-number ratios to form compounds, laying the foundation for modern chemistry.
JEE Main Highest Scoring Chapters & Topics
Just Study 40% Syllabus and Score upto 100%
Download EBook

Mole Concept

  • Mole concept is fundamental topic for entire physical chemistry. The mole is a standard scientific unit used to measure the amount of substance, defined as containing 6.022×1023 entities (Avogadro's number), simplifying chemical calculations.

Empirical Formula and Molecular Formula

  • The empirical formula represents the simplest whole-number ratio of elements in a compound, while the molecular formula provides the actual number of atoms of each element in a molecule.

Stoichiometry and Stoichiometric Calculations

  • Stoichiometry deals with the quantitative relationships of reactants and products in a chemical reaction, allowing for precise calculation of amounts required or produced.

Some Important Concentration Terms

  • Key concentration terms, such as molarity, molality, and mass percentage, are used to express the quantity of solute present in a given amount of solvent or solution.

Overview of the Chapter

Some basic concepts of chemistry are the most basic chapter of chemistry. It has various important concepts that you need to have greater insights for a better understanding of the whole of the chemistry. This article will help you to give important insights into this chapter and will also guide you in some important tips and guidelines.


Nature of Matter

Everything in the universe that has some mass and occupy some space is known as matter. Matter exists in three different physical forms i.e, solid, liquid and gas.

PropertySolidLiquidGas
TightnessVery tightly packedTightly packedLoosely packed
Intermolecular spaceMinimumIntermediateMaximum
Force of attractionMaximumIntermediateMinimum
Kinetic EnergyMinimumIntermediateMaximum
DensityMaximumIntermediateMinimum
VolumeFixedFixedVariable
ShapeFixedVariableVariable
Compressibility factorMinimumIntermediateMaximum

At the macroscopic level, the matter can be classified into two categories i.e, mixtures and pure compounds as shown in the figure.

matter

Mixtures are those substances in which two or more components are mixed. Mixtures are further classified as homogeneous and heterogeneous mixtures. Homogeneous mixtures are the one in which components are present in a fixed ratio and the properties of this kind of mixture are the same throughout, for example, solution of sugar in water. But heterogeneous mixtures are those in which the components are not mixed in a definite ratio and properties of the mixture vary at different positions of the mixture, for example, sand in water.

Also read,

Laws of Chemical Combination

The combination of elements to form some new product follows three basic laws as shown in the figure

download-7

  • Law of conservation of mass: This law states that "matter can neither be created nor destroyed". This simply means that the number of reactants that are used in the reaction will be equal to the number of products formed.
  • Law of definite proportions: This law states that any compound always contains its components in the fixed ratio by mass irrespective of its source and method of preparation.
  • Law of multiple proportions: This law states that when two elements combine to form one or more than one compound, then the masses of one element that combine with the other element are in the ratio of small whole numbers.

Dalton's Atomic Theory

John Dalton proposed a theory about matter and atoms in which he proposed the following postulates:

(i) Matter consists of small individual particles known as 'atoms'.
(ii) All atoms of any particular element have the same
properties and same mass but atoms of different elements have different properties and mass.
(iii) Compounds are formed when atoms of different elements are combined in a fixed ratio.
(iv) Chemical reactions involve the reorganization of atoms.

Mole Concept

A mole is the standard unit to measure the number of particles like atoms or molecules in a given sample. Mathematically, one mole is equal to 6.022 x 1023. In other words, it can be said that it is equal to as many particles as there are atoms in 12g of the carbon-12 isotope. For example, if we have one mole of oxygen gas, that means we have 6.022 x 1023 molecules of O2.

Empirical Formula and Molecular formula

The empirical formula is the simplest whole-number ratio of atoms present in any particular molecule and the molecular formula is the actual representation of the number of atoms present in the molecule.

For example glucose i.e. C6H12O6, its molecular formula is C6H12O6 but its empirical formula is CH2O.
Mathematically, the relation between
empirical formula mass and molecular formula mass is given as follows:

n= Molecular mass empirical formula mass

where n is the simplest ratio.

Limiting Reagent

The reactant is consumed first in the reaction. When we are dealing with the balanced chemical equation, if the number of moles of reactants is not in the ratio of the stoichiometric coefficient of the balanced chemical equation, then there should be one reactant that should be limiting reactant.

% yield

Sometimes, experimentally, the reaction does not undergo 100% completion because of many factors which are involved in the actual industrial processes. So in such cases, we need the concept of % yield.

It is defined as the ratio of actual moles of product(s) formed to the number of moles that should have been theoretically formed assuming 100% completion of the reaction.

% yield = Actual number of moles formed Theoretical moles that should have formed

Stoichiometry and Stoichiometric Calculations

This concept helps us to calculate the mass or amount of reactants and products in the given chemical reaction. For calculations, first, we must have a balanced chemical equation, only then can we predict the mass of reactants and products. For example
The chemical reaction is given as follows:
2H2+O2→2H2O
Now, this chemical equation is a balanced equation, thus we are able to predict that one-mole oxygen will combine with 2 moles of hydrogen and form 2 moles of water, and thus accordingly, we can calculate the masses of the respective elements.

In this concept, we also study the "limiting reagent". It is the substance that is present in reactants in a smaller amount. In other words, a limiting reagent is a substance that will be completely finished or react in the given chemical reaction.

Some important Concentration Terms

  • Mole fraction: It is the ratio of the moles of any substance present in the solution to the total moles of the solution. Mathematically, it is given as follows:
    Mole fraction of A=nAnA+nB
    where nA is the moles of component A and nB is the moles of component B.
  • Molarity: It is the concentration of any substance present in the solution. In other words, it is moles of solute per unit volume of solution in litres. Mathematically, it can be given as follows:
    Molarity = Moles of solute Volume of solution inlitre
  • Molality: It is the moles of solute dissolved in the given amount of solvent. Mathematically, it can be represented as follows:
    Molality = Moles of solute Mass of solvent (Kg)
  • Normality: It is defined as the number of equivalents of solute dissolved in a one-litre volume of solution. Mathematically, it can be represented as follows:
    Normality = Number of equivalents of solute Volume of solution in litre


Related topics

How do you prepare for States of matter?

  • This chapter is the beginning of chemistry. This chapter is one of the most important chapters of the complete chemistry syllabus. Its concepts, laws, numerical, and graphs all are important both for the basic foundation of chemistry and for scoring good marks in the examination.
  • Read this chapter carefully, as it has all the basic concepts like the mole concept, stoichiometry, molarity, normality, etc.
  • This chapter is the foundation stone of the whole of the chemistry syllabus.
  • Rest this chapter is very simple, just be regular and be consistent in your numerical practice.

Real-life application based on Some Basic Concepts in Chemistry

  • In cooking, it is always necessary to know the exact amount of ingredients to be add in the food to get the best and tasty dish. This calculation of ingredients in stoichiometry.
    chef
  • Saturn planet is much larger than earth but still, it is less dense. The specific gravity of Saturn is even less than 1.
    saturn
  • The GPS system that we use for finding out the way is related to stoichiometry. All these signals come from satellites. The stoichiometry helps to calculate the fuel and its components of reactions in the complete journey of satellites.
    satalitemap

Prescribed Books for the States of Matter

First, you must finish the class XI NCERT textbook and solve each and every example and unsolved question given in it. Then for advanced level preparation like JEE and NEET, you must follow R.C. Mukherjee and O.P. Tandon. You must definitely solve the previous year papers. Meanwhile, in the preparation, you must continuously write the mock tests for the depth of knowledge. Our platform will help you to provide with the variety of questions for deeper knowledge with the help of videos, articles and mock tests.

Also read,

Recommended topic video on (Some Basic Concepts of Chemistry)


Some Solved Examples

Example 1:

A sample of KCl is placed in 50 ml of solvent. What should be the mass (in gm) of the sample for the molarity to be 2M ?

1) (correct) 7.45

2) 7.81

3) 6.81

4) 7

Solution

Number of Moles = molarity x volume

= 2 x 0.05 = 0.1

So, mass = (39 + 35.5) x 0.01g = 7.45 g

Hence, the answer is an option (1).

Example 2:

The amount (in g) of sugar (C12H22O11) required to prepare 2L of its 0.1 M aqueous solution is:

1) 17.1

2) (correct) 68.4

3) 136.8

4) 34.2

Solution

Molarity -Molarity (M) = (Number of moles of solute)/(volume of solution in litres)

It is defined as the number of moles of the solute in 1 litre of the solution.

As we have learned in the mole concept.

The formula of molarity =(n)solute Vsolution ( in lit )

0.1=wt3422

wt(C12H22O11) = 68.4 gram

Hence, the answer is the option (2).

Example 3:

Calculate the molality of a solution containing of Acetic acid in Ethanol if the mass of solute = 10g and the density of Ethanol = 0.789 gmL-1.

1) 0.2112

2) 0.2012

3) 0.1992

4) 0.2002

Solution

We know.

Molality (m) = (number of moles of solute)/(mass of solvent in kg)

Now,

Moles of solute Acetic acid = mass / molar mass

=1060 moles

If Volume of ethanol = 1 L

Formula, Density = mass/volume

So,

Weight of ethanol = 1000 x 0.789 = 789g = 0.789 Kg

Molality = mass of solute mass of solution in kg Molality =1060×7891000=0.2112 m/kg

Hence, the answer is (0.2112 m/kg).

Conclusion

Basic concepts of chemistry tells about various important concepts like the Mole concept and stoichiometry which play an important role in industry-based setups to find the required amount of reagents. Various chemical reactions and their limiting agents can be identified using these concepts. Students are suggested to read the prescribed books above in this article to get a good command on the entire subject.

Frequently Asked Questions (FAQs)

1. What is the definition of 1 mole?

Number of moles = Weight / Molecular weight

One mole of substance is equal to 6.023 * 1023 units of that substance.

2. What is the SI unit of molality?

Unit of Molality is Moles per Kilogram.

3. What are the 3 important types of concentration?

Molarity, Molality and Normality are the 3 important terms related to concentration.

Articles

Get answers from students and experts
Back to top