'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 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. In this chapter, there are other important topics as well as the mole concept, stoichiometry, molarity, normality, etc.
There are some important real life application based on the chapter of 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.
Property |
Solid |
Liquid |
Gas |
Tightness |
Very tightly packed |
Tightly packed |
Loosely packed |
Intermolecular space |
Minimum |
Intermediate |
Maximum |
Force of attraction |
Maximum |
Intermediate |
Minimum |
Kinetic Energy |
Minimum |
Intermediate |
Maximum |
Density |
Maximum |
Intermediate |
Minimum |
Volume |
Fixed |
Fixed |
Variable |
Shape |
Fixed |
Variable |
Variable |
Compressibility factor |
Minimum |
Intermediate |
Maximum |
At the macroscopic level, the matter can be classified into two categories i.e, mixtures and pure compounds as shown in the figure.
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.
The combination of elements to form some new product follows three basic laws as shown in the figure
John Dalton proposed a theory about the 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 the fixed ratio.
(iv) Chemical reactions involve the reorganization of atoms.
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 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:
where n is the simplest ratio.
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 we can predict the mass of reactants and products. For example
The chemical reaction is given as follows:
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 about the "limiting reagent". It is the substance that is present in reactants in a smaller amount. In other words, limiting reagent is a substance which will be completely finished or react in the given chemical reaction.
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 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.
Chapters No. |
Chapters Name |
Chapter 2 |
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Chapter 3 |
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Chapter 4 |
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Chapter 5 |
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Chapter 6 |
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Chapter 7 |
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Chapter 8 |
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Chapter 9 |
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Chapter 10 |
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Chapter 11 |
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Chapter 12 |
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Chapter 13 |
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Chapter 14 |
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Chapter 15 |
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Chapter 16 |
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Chapter 17 |
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Chapter 18 |
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Chapter 19 |
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Chapter 20 |
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Chapter 21 |
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Chapter 22 |
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Chapter 23 |
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Chapter 24 |
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Chapter 25 |
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Chapter 26 |
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Chapter 27 |
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Chapter 28 |
In the reaction,
Option 1)
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Option 2)
|
Option 3)
|
Option 4)
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How many moles of magnesium phosphate, will contain 0.25 mole of oxygen atoms?
Option 1)
0.02 |
Option 2)
3.125 × 10-2 |
Option 3)
1.25 × 10-2 |
Option 4)
2.5 × 10-2 |
If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will
Option 1)
decrease twice |
Option 2)
increase two fold |
Option 3)
remain unchanged |
Option 4)
be a function of the molecular mass of the substance. |