Chemistry Podcast

Monday, 27 July 2015

10 Class- Chemical Reactions and Equations

Chemical Reactions and Equations


  • ·       Every chemical change is a chemical reaction.
  • ·       General observation to identify whether a chemical reaction take place or not-
1.    Change in state.
2.    Change in color.
3.    Evolution of gas.
4.    Change in temperature.

Chemical Equations:

Any equation which describes the change of reactants to products is called chemical reaction.
Reactant1+Reactant2+…………--->   Product1+Product2+………

In chemical equations reactants are placed on left hand side and products are placed on right hand side and arrow sign is placed between them. Direction of arrow shows the direction of reaction.
Example: chemical equations in words.
Magnesium + Oxygen {Reactants} .------->  Magnesium-Oxide {Product}

Writing a Chemical Equation by using Chemical Formula:

In it we use symbols instead of words to write a chemical equation.
Example: Mg + O2 .-----> MgO

     1.    Unbalanced Chemical Equation:

Equation in which number of atoms on reactant side is not equal to number of atoms on product side, means mass is not same on both sides.
         Example: Mg + O2 -----> MgO
                          Fe +  H2-----> Fe3O4 + H2

     2.    Balanced Chemical Equation:

Equation in which number of atoms on reactant side is equal to number of atoms on product side, means mass is same on both sides.
         Example: 2Mg + O2 ----> 2MgO
                          3Fe + 4H2O -----> Fe3O4 + 4H2

Writing Symbols of Physical State:

                                                          Reactants and products are written with their physical state to make equation more informative.
Physical State
Notation
Gaseous
(g)
Liquid
(l)
Aqueous
(aq)
Solid
(s)
Example: 3Fe (s) + 4H2O (g) -----> Fe3O4 (s) + 4H2 (g)
·       Example of reactions with reaction condition like pressure, temperature, catalyst etc.
10 classes science chemistry note

Types of Chemical Reactions:

                                                Chemical reactions are reactions which involve making and breaking of bonds between atom to yield new substances.

    1.    Combination Reaction:

These are the reactions in which one single product is formed from two or more reactants.
Example: i. Formation of Calcium Hydroxide.
CaO (s)(quick lime) + H2O (l) -------> Ca(OH)2 (aq)(slaked lime)
ii. Burning of Coal.
C (s) + O2 (g) ------> CO2 (g)
iii. Formation of Water.
2H2 (g) + O2 (g) ------> 2H2O (l)

    2.    Displacement Reaction:

These are the reactions in which highly reactive metal displaces less reactive metal from their solution.
Example: i. Fe (s) + CuSO4 (aq)(copper sulphate) -------> FeSO4 (aq)(iron sulphate) + Cu (s)
 ii. Zn (s) + CuSO4 (aq)(copper sulphate) -------> ZnSO4 (aq)(zinc sulphate) + Cu (s)
iii. Pb (s) + CuCl2 (aq)(copper chloride) -------> PbCl2 (aq)(lead chloride) + Cu (s)

    3.    Double Displacement Reaction:

These are the reactions in which exchange of ions between reactants occur.
Example: Na­2SO4 (aq)(sodium sulphate) + BaCl2 (aq)(barium chloride) -------> BaSO4 (s)(barium sulphate) + 2NaCl (aq)(sodium chloride)

    4.    Oxidation and Reduction Reaction:

1.1.        Oxidation:

These are the reactions in which a substance loses hydrogen or gain oxygen.
          Example: 2Cu + O2 + Heat ----------> 2CuO

1.2.        Reduction:

These are the reactions in which a substance gain hydrogen or loses oxygen.
          Example: CuO + H2 + Heat ----------> Cu + H2O

1.3.        Redox Reaction:

These are the reactions in which one reactant gets reduced while other reactant gets oxidized. This type of reaction is also known as Oxidation-Reduction Reaction or Redox Reaction.
Example:
i.                   CuO + H2 + Heat ---------> Cu + H2O
In above reaction-
                   H2 ---------> H2O (oxidation)

                   CuO --------> Cu (reduction)

ii.                ZnO + C --------->  Zn + CO
iii.             MnO2 + 4HCl --------> MnCl2 + 2H2O + Cl2

Observable Effect of Oxidation Reduction in Everyday Life:

1.    Corrosion:


   Attack on metals by moisture, acids, oxygen etc., which corrode metals is called corrosion.

Example: Rusting of Iron, Black coating on Silver, Green coating on Copper.

2.    Rancidity:


   Change in taste and smell of food material prepared by using fat or oil, because fat or oil get oxidized and become rancid.

Endothermic Reaction:


                                      These are the reactions in which heat is absorbed during reaction.

Example: NH4Cl (s) + H2O (l) + Heat --------> NH4Cl (aq)

Exothermic Reaction:


                                      These are the reactions in which heat is evolved during reaction.

Example: CH4 (g) + 2O2 (g) --------> CO2 (g) + 2H2O (g) + Heat

Precipitation Reaction:


                                      These are the reactions in which insoluble substance called precipitate is obtained when reaction completes, is known as precipitation reaction.

Example: Na2SO4 (aq) + BaCl2 (aq) -------> BaSO4 (s) + 2NaCl (aq)

Saturday, 25 July 2015

Maths 5th Class

5th Class Mathematics

Mathematics is very necessary in understanding chemistry very well, so we now publish some basics of mathematics from class 5th maths. Hope you like our work.
Multiplication:  operation to get no. of times of given no. eg- 5x5 = 25
Vedic trick of multiplication-
HCM (Highest Common Multiple) and LCM (Lowest Common Multiple) :

HCM: 5

LCM: 5x3x2x5x7=1050



Fraction=Numerator/Denominator
Profit = selling price - cost price
Loss = cost price - selling price
Profit% = (profit x 100)/cost price
Loss% = (loss x 100)/cost price
Amount = principle + interest
Simple Interest = principle x rate% x time
Simple Interest = (principle x rate x time)/100
AM = antemeridian
PM = postmeridian
Big Units
Small Units
Kilo = 1000 times
Deci = 1/10
Hecto = 100 times
Centi  = 1/100
Deco = 10 times
Mili = 1/1000
Perimeter:
Perimeter of Triangle = sum of lengths of all three sides of triangle.
Perimeter of Rectangle = 2 (Length + Breadth)
Perimeter of Square = 4 x ( Length of any one side)
Area:
Area of Rectangle = Length x Breadth
Area of Square = Side x Side
Different Angles used in Mathematics:
  • Acute Angle < 90o
  • Right Angle = 90o
  • 90o < Obtuse Angle < 180o
  • Zero Angle = 0o
  • Straight Angle = 180o
Different Triangles used in Mathematics:
  • Right Triangle = Triangle containing one 90o angle
  • Equilateral Triangle = Triangle having three equal sides and three equal angles, and have each angle of 60°.
  • Isosceles Triangle = Triangle having two equal sides and two equal angles.
  • Scalene Triangle = triangle having different length of sides.
  • Acute Triangle = Triangle having all three angles less than 90o
  • Obtuse Triangle = Triangle having one angle more than 90o
 

Friday, 24 July 2015

what is chemical and what is chemical reaction

BASICS OF CHEMISTRY

Chemical-any substance that has a defined composition
Chemical reaction- the process by which one or more substances change to produce one or more different substances
States of matter-the physical forms of matters, which are solid, liquid, gas, and plasma 
Reactant- a substance or molecule that participates in a chemical reaction  Product- a substance that forms in a chemical reaction
Matter-anything that has mass and takes up space
Volume-a measure of the size of a body or region in three-dimensional space
Mass-a measure of the amount of matter in an object; a fundamental property of an object that is not affected by the forces that act on the object, such as the gravitational force
Weight- a measure of the gravitational force exerted on an object; its value can change with the location of the object in the universe
Quantity- something that has magnitude, size, or amount
Unit- a quantity adopted as a standard of measurement
Conversion Factor- a ration that is derived form the equality of two different units that can be used to convert from one unit to the other
Physical property- a characteristic of a substance that does not involve a chemical change, such as density, color, or hardness
Density –the ratio of the mass of a substance to the volume of the substance; often expressed as grams per cubic centimeter for solids and liquids and as grams per liter for gases
Chemical Property- a property of matter that describes a substance’s ability to participate in chemical reactions
Atom- the smallest unit of an element that maintains the properties of that element
Pure Substance- a sample of matter, either a single element or compound, that has definite chemical and physical properties
Element- a substance that cannot be separated or broken down into simpler substances by chemical means’ all atoms of an element have the same atomic number
Molecule- the smallest unit of a substance that keeps all of the physical and chemical properties of that substance; it can consist of one atom or two or more atoms bonded together
Compound- a substance made up of atoms of two or more different elements joined by chemical bonds
Mixture- a combination of two or more substances that are not chemically combined
Homogeneous- describes something that has a uniform structure or composition throughout
Heterogeneous- composed of dissimilar components
by: Chemistry Notes Info www.ChemistryNotesInfo.Blogspot.Com

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