Some Basic Concept Of Chemistry

Some Basic Concept of Chemistry

•   Basic constituents of matter: - Atoms and molecules.

• What is chemistry: - It is the branch of science which deals with the study of composition, properties and interaction of matter.

• Matter: - Anything which has mass and occupies space known as matter. Ex: - Water, pencil, pen, book etc.

Physical states of matter

=> Solid, liquid, gas.

Physical state	Definite volume	Definite shape	Example
Solid	Yes	Yes	Book, pen
Liquid	Yes	No	Water, milk
Gas	No	No	CO2, Air

Temperature & pressure effect on physical state

            Classification of matter: -

1.       Mixture:

a.       Homogeneous mixture

b.      Heterogeneous mixture

2.       Pure substance:

a.       Elements

b.      Compounds

1.       Mixture: - It contains two or more substances in any ration known as its components.

Ex: - air, tea etc.

a.       Homogeneous mixture: - its components are completely mix with each other and have uniform composition throughout the solution.

Ex: - sugar solution, air.

b.      Heterogeneous mixture: - its components do not have uniform composition throughout solution sometimes different components observed.

Ex: - mixture of salt & sugar, sand & soil.

2.       Pure substances: - these have fixed composition.

Ex: - copper, gold, water etc.

a.       Elements: - It consists of only one type of particles (i.e. atoms or molecules)

Ex: - H₂, O₂, Au, Ag.

b.      Compounds: - It consists of two or more atoms to give a molecule of compound

Ex: - CO₂, NH₃, H₂O.

Properties of matter

•      1)      Physical properties: - Those properties which can be measured or observed.
•      2)      Chemical properties: - those properties in which chemical changes occurs.
•      Ex: - Acidity, Basicity, Combustibility etc.
•      SI: - International System of units
•   Ø   SI Units are established by 11^th general conference on weight and measures.
•   Ø   SI have seven fundamental units.
•   Ø   Other units are divided from seven fundamental units.

SI Table

Base physical quantity	Symbol for quantity	SI units name	SI units symbol
Length	l	Metre	m
Mass	m	Kilogram	Kg
Time	t	Second	s
Current	I	Ampere	A
Temperature	T	Kelvin	K
Amount of substance	n	Mole	Mol
Luminous intensity	Iv	candela	Cd

Prefixes for SI Units

Multiple	Prefix	Symbol
10-24	Yocto	y
10-21	Zepto	z
10-18	Atto	a
10-15	Femto	f
10-12	Pico	p
10-9	Nano	n
10-6	Micro	m
10-3	Milli	m
10-2	Centi	c
10-1	Deci	d
10	Deca	da
102	Hecto	h
103	Kilo	k
106	Mega	M
109	Giga	G
1012	Tera	T
1015	Peta	P
1018	Exa	E
1021	Zeta	Z
1024	yotto	Y

Mass:- amount of matter in object

=> 1 kg = 1000 gram

Weight: -force on the object by gravity.

Volume: - (length)³

=>  1 L = 1000 ml, 1000 cm³ = 1dm³

Density: - Amount of mass per unit volume.

=>  SI unit :- Kgm^-3

Temperature:- It is the measurement of cooling or warming.

Three scales

=>  ⁰C (Degree Celsius)

=>  ⁰F degree Fahrenheit)

=>  k (Kelvin)

=>  freezing point of water = 0 ⁰C

=>  Boiling point of water = 100 ⁰C

Relationship

Or,

k = ⁰C + 273.15

Precision:- Closeness of various measurement for same quantity.

Accuracy:- It is the agreement of a particular value to the true value of the result.

Significant figure:- The meaningful digits which are known with certainty.

Laws of chemical combinations

1)      Law of conservation of mass:- According to this law “matter can neither be created nor destroyed” Given by Antone Lovoisin in 1789.

2)      Law of definite proportion:- According to this law “A given compound always contains exactly the same proportion of elements by weight known as law of definite proportion or law of definite composition” given by Joseph Proust in 1754-1826

3)      Law of multiple proportion:- According to this law “if two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of small whole number” given by Dalton in 1803.

4)      Gay lussac’s law of gaseous volume:- According to this law “gases combine or are produced in chemical reactions they do so in a simple ratio by volume provided to all gases are at the  same temperature and pressure” given by Gay Lussac’s in 1808.

5)      Avogadro’s law:- According to this law “Equal volume of gases at same temperature & pressure should contain equal no. of molecules” given by Avogadro in 1811.

Dalton’s Atomic Theory

         i.            Matter consists of indivisible atoms.

       ii.            All the atoms of a element have identical properties (same properties) i.e. atoms of a element have same mass while atoms of different elements have different masses.

      iii.            Compounds formed when atoms of different elements combine in fixed ratio.

     iv.            Chemical reactions involve reorganization (rearrangement) of atoms.

Atomic mass unit = 1/12^th mass of one carbon¹² atom.

Molecular mass = It is the sum of atomic masses of the elements present in a molecule.

Mole :- It is the amount of substance equal to Avogadro no. (N_A). = 6.022 ´ 10²³ atoms/mole.

Molar mass:- Mass of one mol of a substances in gram is known as molar mass.

Mass % of an element = mass of that element in compound ´ 100/ molar mass of the compound.

Empirical formula :- It is the simplest whole no. ratio of various atoms present in a compound.

Molecular formula:- It is the exact no. of different types of atoms present in a molecule of a compound.

Concentration expression methods

                     i.          

                   ii.            Mole fraction :- If a substance ‘A’ is dissolved in ‘B’ and their no. of moles are n_A and n_B respectively.

Online Video Classes of 11th Class Chemistry

Chapter 1- Some Basic Concept of Chemistry

Some Basic Concepts of Chemistry Class 11 MCQ

1. If a matter has definite volume and definite shape, then it is :

Solid
Liquid
Gas
All of the Above

2. Mole is SI unit of :

Current
Temperature
Amount of Substance

Luminous intensity

3. A measured temperature is 100 ⁰F on Fahrenheit scale, then what is this reading be on Celsius scale :

11.2 ⁰C

78 ⁰C

102.7 ⁰C

37.8 ⁰C

4. What amount of H­₂O produced by combustion of 32 g of CH₄ :

36 g
18 g
72 g
90 g

5. How many moles of CH₄ is needed to get 44 gram CO₂ after combustion :

0.5 mol of Methane
1 mol of Methane
2 mol of Methane
4 mol of Methane

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