Class 10th
science chapter-1
Chemical reactions and equations
Top definitions :
1 . Chemical reaction : A chemical reaction involves a chemical change in which substances react to form new substances with entirely new properties , Substances that react or take part in the reaction are known as reactants and the Substances formed are known as products .
2 . Physical change : If a change involves change in colour or state but no new substance is formed , then it is a physical change .
3 . Chemical change : If a change involves formation of new substances , it is a chemical change .
4 . Chemical equation : The symbolic representation of a chemical reaction is called a chemical equation .
5 . Exothermic and endothermic reactions : If heat is evolved during a reaction , then such a reaction is known as exothermic reaction . If heat is absorbed from the surroundings , then such a reaction is known as endothermic reaction
6 . Combination reaction : Combination reaction is a reaction in which 2 or more substances Combine to give a single product .
7 . Decomposition reaction : In a decomposition reaction , a single reactant decomposes to give 2 or more products . Decomposition reactions require energy in the form of heat , light or electricity
8 . Displacement reaction : A reaction in which a more active element displaces less active element from its salt solution .
9. Reactivity series: The Reactivity series is a list of decreasing reactivity. The most reactive metal is placed at the top and the least reactive metal is placed at the bottom,
10. Double displacement reaction: A chemical reaction in which there is an exchange of ions between reactants to give new substances.
11. Precipitation reaction: An insoluble solid is known as the precipitate. Such reactions are also known as precipitation reactions.
12. Redox reaction: A reaction, in which oxidation and reduction takes place. 13. Oxidation: Oxidation is a chemical process in which a substance gains oxygen or loses hydrogen.
14. Reduction: Reduction is a chemical process in which a substance gains hydrogen or loses oxygen.
Key learning:
1. A chemical reaction involves a chemical change in which substances are completely new properties. Substances that react or take part in the reaction are known as reactants and the substances formed are known as products.
2 . During a chemical reaction, there is a breaking of bonds between reacting molecules to give products.
3. A chemical reaction can be observed by any of the following observations:
a) Evolution of a gas
b) Change in temperature
c) Formation of a precipitate
d) Change in color
e) Change of state
4. Physical change: If a change involves change in color or state but no new substance is formed, then it is a physical change.
5. Chemical change: If a change involves formation of new substances, it is a chemical change.
6. Exothermic and endothermic reactions: If heat is evolved during a reaction, then such a reaction is known as Exothermic reaction. If heat is absorbed from the surroundings, then such an reaction is known as endothermic reaction.
7. Chemical equation: The symbolic representation of a chemical reaction.
8. Features of a chemical equation:
a. The reactants are written on the left hand side with a plus sign between them.
b. The products are written on the right hand side with a plus between them
c. An arrow separates the reactants from the products. The arrow head points towards the products and indicates the direction of the reaction.
9. Skeletal chemical equation:
A chemical equation which simply represents the symbols and formulae of reactants and products taking part in the reaction is known as skeletal chemical equation for a reaction. For example: For the burning of Magnesium in the air, Mg + 02 → Mg0 is the skeletal equation.
10. Balanced chemical equation:
A balanced equation is a chemical equation in which number of atoms of each element is equal to both sides of the equation i. e. Number of atoms of an element on reactant side = number of atoms of that element on the product side.
11. As per the law of conservation of mass, the total mass of the elements present in the chemical reaction is equal to the total mass of the elements present in the reactants.
. 13. Types of chemical reactions:
a Combination reaction
b Decomposition reaction
c. Displacement reaction
d Redox reaction
14 Combination reaction is a reaction in which 2 or more substances combine to give a single product. Combination is possible between two elements, an element and a compound or between 2 compounds
15. Decompression reaction: In a decompression reaction, a single reactant decomposes to give 2 or more products. Decomposition reactions require energy in the form of light, light or electricity.
16 Types of decomposition reactions:
a. Decomposition reactions which are known as thermolytic decomposition reactions
b. Decomposition reactions which are lighted are known as photolytic decomposition reactions.
c. Decomposition reactions which are called electrolytic decomposition reactions
science chapter-1
Chemical reactions and equations
Top definitions :
1 . Chemical reaction : A chemical reaction involves a chemical change in which substances react to form new substances with entirely new properties , Substances that react or take part in the reaction are known as reactants and the Substances formed are known as products .
2 . Physical change : If a change involves change in colour or state but no new substance is formed , then it is a physical change .
3 . Chemical change : If a change involves formation of new substances , it is a chemical change .
4 . Chemical equation : The symbolic representation of a chemical reaction is called a chemical equation .
5 . Exothermic and endothermic reactions : If heat is evolved during a reaction , then such a reaction is known as exothermic reaction . If heat is absorbed from the surroundings , then such a reaction is known as endothermic reaction
6 . Combination reaction : Combination reaction is a reaction in which 2 or more substances Combine to give a single product .
7 . Decomposition reaction : In a decomposition reaction , a single reactant decomposes to give 2 or more products . Decomposition reactions require energy in the form of heat , light or electricity
8 . Displacement reaction : A reaction in which a more active element displaces less active element from its salt solution .
9. Reactivity series: The Reactivity series is a list of decreasing reactivity. The most reactive metal is placed at the top and the least reactive metal is placed at the bottom,
10. Double displacement reaction: A chemical reaction in which there is an exchange of ions between reactants to give new substances.
11. Precipitation reaction: An insoluble solid is known as the precipitate. Such reactions are also known as precipitation reactions.
12. Redox reaction: A reaction, in which oxidation and reduction takes place. 13. Oxidation: Oxidation is a chemical process in which a substance gains oxygen or loses hydrogen.
14. Reduction: Reduction is a chemical process in which a substance gains hydrogen or loses oxygen.
Key learning:
1. A chemical reaction involves a chemical change in which substances are completely new properties. Substances that react or take part in the reaction are known as reactants and the substances formed are known as products.
2 . During a chemical reaction, there is a breaking of bonds between reacting molecules to give products.
3. A chemical reaction can be observed by any of the following observations:
a) Evolution of a gas
b) Change in temperature
c) Formation of a precipitate
d) Change in color
e) Change of state
4. Physical change: If a change involves change in color or state but no new substance is formed, then it is a physical change.
5. Chemical change: If a change involves formation of new substances, it is a chemical change.
6. Exothermic and endothermic reactions: If heat is evolved during a reaction, then such a reaction is known as Exothermic reaction. If heat is absorbed from the surroundings, then such an reaction is known as endothermic reaction.
7. Chemical equation: The symbolic representation of a chemical reaction.
8. Features of a chemical equation:
a. The reactants are written on the left hand side with a plus sign between them.
b. The products are written on the right hand side with a plus between them
c. An arrow separates the reactants from the products. The arrow head points towards the products and indicates the direction of the reaction.
9. Skeletal chemical equation:
A chemical equation which simply represents the symbols and formulae of reactants and products taking part in the reaction is known as skeletal chemical equation for a reaction. For example: For the burning of Magnesium in the air, Mg + 02 → Mg0 is the skeletal equation.
10. Balanced chemical equation:
A balanced equation is a chemical equation in which number of atoms of each element is equal to both sides of the equation i. e. Number of atoms of an element on reactant side = number of atoms of that element on the product side.
11. As per the law of conservation of mass, the total mass of the elements present in the chemical reaction is equal to the total mass of the elements present in the reactants.
. 13. Types of chemical reactions:
a Combination reaction
b Decomposition reaction
c. Displacement reaction
d Redox reaction
14 Combination reaction is a reaction in which 2 or more substances combine to give a single product. Combination is possible between two elements, an element and a compound or between 2 compounds
15. Decompression reaction: In a decompression reaction, a single reactant decomposes to give 2 or more products. Decomposition reactions require energy in the form of light, light or electricity.
16 Types of decomposition reactions:
a. Decomposition reactions which are known as thermolytic decomposition reactions
b. Decomposition reactions which are lighted are known as photolytic decomposition reactions.
c. Decomposition reactions which are called electrolytic decomposition reactions
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