Chemical reaction and equation
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Basic keywords
1. Chemical reaction:
The process in which substance with new properties are formed is known as chemical reaction.2. Reactants:
The substances that undergo in a chemical reaction are known as reactants.3.Products:
The substances which are formed as a result in chemical reaction are known as products.
e.g. Na+H₂O ➡️ NaOH+H₂
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Identification of chemical reaction
A chemical reaction can be identified by either of the following observations.
- change in state
- change in colour
- evolution of gas
- change in temperature
- formation of a precipitate
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Types of chemical equation
1. Unbalanced equation
The reaction which is not balanced and does not follow the law of conservation of mass is called unbalanced chemical equation.
e.g. Mg+O₂ ➡️ Mgo
2. Balanced equation
Balanced chemical equation is that in which the total number of atoms of each element are equal on both side of equation and follows the law of conservation of mass.
e.g. Na+H₂O➡️ NaOH+H₂
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Making a chemical equation more informative
We can make chemical equation more informative by following points.
- Physical state of substances
- Reaction conditions
- Evolution or absorption of energy
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Types of chemical reactions
1. Combination reaction
Reaction in which two or more reactants combine to form a single product is called combination reaction.
e.g. calcium oxide reacts vigorously with water to form calcium hydroxide the reaction is highly exothermic that is a lot of heat is produced during the reaction
CaO+H₂O ➡️ Ca(OH)₂+Heat
2. Decomposition reaction
a reaction in which single reactant breaks to form two or more products is known as decomposition reaction.
It is of three types:
1.Thermal decomposition: This reaction use the energy in the form of heat for decomposition of the reactant
2.Electrolysis:The reactions involve the use of electrical energy for the decomposition of the reactant molecules.
3. Photolysis/photochemical decomposition: These reaction involve the use of light energy for the purpose of decomposition.
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2. Corrosion is a waste westphal process in most of cases every year terms of various metals a specially iron gets wasted in the country. Hence, it is necessary to prevent corrosion.
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3. Photolysis/photochemical decomposition: These reaction involve the use of light energy for the purpose of decomposition.
3. Displacement reaction
when an element displaces another element from its compound it is called displacement reaction.
Displacement reaction is of two types:
1. Single displacement reaction: it is a type of chemical reaction where an element reacts with a compound and takes the place of another element in that compound is called single displacement reaction.
e.g. Zn+CuSO₄➡️ZnSO₄+Cu
2. Double displacement reaction:the reaction in which two different ions or group of atoms in the reactant molecules are displaced by each other is called double displacement reaction . It is also called as precipitation reaction in which precipitate is produced.
e.g. on adding sodium sulphate to barium chloride a curdy white precipitate of barium sulphate and NaCl are formed.
Na₂SO₄+BaCl₂➡️BaSO₄+2NaCl
Oxidation and reduction reactions
Oxidation:
It can be defined as the process in which oxygen is added to a substance .
OR
The process in which hydrogen is removed from a substance.
OR
The process in which a substance loses electrons.
Reduction:
The process in which oxygen is removed from a substance.
OR
The process in which hydrogen is added to a substance.
OR
THE PROCESS IN WHICH SUBSTANCE GAINS ELECTRONS.
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Redox reaction
Those reactions in which oxidation and reduction take place simultaneously are called a redox reaction.
e.g. CuO+H₂➡️Cu+H₂O
In the following reaction of copper II oxide is using Oxygen and is being reduced expression is added to hydrogen and oxidised.
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Exothermic reaction.
The reactions which are accompanied by the evolution of feet are called exothermic reaction.
e.g. reaction of methane with oxygen produces carbon dioxide and water along with heat.
Endothermic reaction
The reaction which occur by the absorption of heat energy are called endothermic reaction.
e.g. when mercuric oxide is heated it produces Mercury + oxygen
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Effect of oxidation reactions in everyday life
Corrosion:
The phenomenon due to which metals are slowly eaten away by the reaction of air, water and chemicals present in the atmosphere is called corrosion.
e.g. application of raining when you get coated with reddish brown powder when left for sometime this process is commonly known as rusting of iron.
Effects of corrosion:
1.corrosion causes damage to ka bodies, bridges iron railings, seats and all objects made of metals, especially those which are made up of iron
2. Corrosion is a waste westphal process in most of cases every year terms of various metals a specially iron gets wasted in the country. Hence, it is necessary to prevent corrosion.
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Rancidity
it is the process of snow oxidation of oils and fats which are volatile in nature present in the food material resulting in the change of smell and taste in them.
The methods to prevent rancidity are
- Packing of food materials in airtight containers.
- Refrigeration of cooked food at low temperatures
- packing of food items like potato wafers at cetera in packets containing nitrogen gas instead of air
- Biting antioxidants example B H A and B H T
End
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