SCIENCE CLASS 10th chapter 1st
CHEMICAL REACTION AND EQUATION
PHYSICAL CHANGE :- Those changes in which no new substance are formed are called physical changes.
Example:- Melting of ice, boiling of water & glowing of electric bulb etc.
PROPERTIES OF PHYSICAL CHANGE:-
1. No new substanceare formed in physical change.
2. The physical change are temporary changes which can be reserved easily to form the original substances.
CHEMICAL CHANGE :- Those change in which new substances are formed, are called chemical change.
Example:- Burning of paper, rusting of iron, ripening of fruit, coocking of food etc.
PROPERTIES OF CHEMICAL CHANGE:-
1. Always a new substance is formed.
2. The chemical change are permanent change in which matter can't be converted into its original form.
3. Colour,nature,taste,etc are get change.
CAUSE OF CHEMICAL CHANGE(Chemical Reaction):- Chemical are found due to chemical reaction. A chemical reaction is the process in which two or more substance reacts with each other to produce a new substance.
CHEMICAL EQUATION:- The short term representation of a chemical reaction with help of symbols in the form of equation is called chemical equation.
METHOD TO WRITE A CHEMICAL EQUATION:-Chemical equation can be written by following method:-
1. Write the word equation for the given chemical equation.
2. Write the reactant on left and product on right side and place an arrow from left to right.
3. If more than one reactant or product are found than place (+)between them.
4. Write the symbol equation for word equation.
Example:- Hydrogen and Oxygen combined together to form water.
write chemical equation for the reaction.
(i)-making the word equation.
hydrogen+oxygen = water
H2+O2 = H2O
UNBALANCED EQQUATION:- The equation in which number of atom are unequal on both side of equation is called unbalanced equation.
BALANCED EQUATION:- The equation in which the number of atoms are equal on both side of equation is called balanced equation.
METHOD TO WRITE A BALANCED CHEMICAL EQUATION:-
Following method are applied to balanced a chemical equation:-
1. write the word equation and then symbol equation for the reaction.
2. count the number of atoms on bath side on chemical equation and then balanced the unequal number of atoms on both side.
3. balance those atoms firstly which have maximum number and then balance other atom.
4. write the physical condition of reactant and product.
Example:- Write the chemical equation when iron reacts with water to produce ironoxide, hydrogen gas.
Solve:-(i) write the word equation.
iron + water ------- ironoxide + hydrogen
(ii) write the symbol equation.
Fe + H2O--------Fe3O4 + H2
(iii) balancing the equation.
Element L.H.S R.H.S
Fe 1 3
H 2 2
O 1 4
(iv) to balance the O atom-----4*H2O
Fe + 4H2O--------Fe3o4 + H2
(v) to balance the Fe atom------3*Fe
3Fe + 4H2O-------Fe3O4 + H2
(vi) to balance H atom---------4*H2
3Fe + 4H2O-------Fe3O4 + 4H2
(vii) write the state.
3Fe(s) + 4H2O(g)-------Fe3O4(s) + 4H2(g)
TYPES OF CHEMICAL REACTION:-
Chemical reaction have following type :-
1. COMBINATION REACTION:- The reaction in which two or more substance combine together to produce a single product called combination reaction.
Example:- A + B ----- C
(i) burning of coal.
C(s) + O2(g) ---------CO2(g)
2. EXOTHERMIC CHEMICAL REACTION:-Reaction in which heat is released along with the formation of products are called exothermic chemical reaction.
Example:-Burning of natural gas.
CH4(g) + 2O2-----CO2(g) + 2H2O(g)
3. ENDOTHERMIC REATION:- Reaction in which energy is absorbed are known as endothermic reaction.
3. DECOMPOSITION REACTION:- The reaction in which a reactant is broken down into two or more part are called decomposition reaction.
Example:-AB------A + B
CaCO3 + CaO + CO2
DECOMPOSION REACTION HAVE FOLLOWIN TYPE:-
(a). THERMAL DECOMPOSITION REACTION:- When decomposition reaction takes place due to the effect of temperater then the reaction is known as thermal decomposition reaction .
Example:- 2AgBr------2Ag + Br2
(b). PHOTO CHEMICAL DECOMPOSITION REACTION:- When a substance broken down into two or more substance in the presence of sunlight is called photo chemical decomposition reaction.
2AgClsunlight------2Ag + Cl2
NOTE:- The reaction is used in black and white photography.
(c). ELECTRIC DECOMPOSITION REACTION:- This type of decomposition reaction takes place due to the effect of electricity.
Example:- 2H2OacidH+---------2H2 + O2
4. DISPLACEMENT REACTION:- The reaction in which one atom of an element takes place the the position of other atom in chemical compound is called displacement reaction.
Example:-Zn + CuSO4---------ZnSO4 + Cu
5. DOUBLE DISPLACEMENT REACTION:- The reaction inwhich any atom is exchange between two chemical substance are called double displacement reaction.
Example:- Na2SO4 + BaCl2---------BaSO4 + 2NaCl
6. OXIDATION REACTION:- The reaction in which oxygen is combined to substance is called oxidation reaction.
Example:- C + O2--------CO2
7. REDUCTION REACTION:- The reaction in which oxygen released from the substance is called reduction reaction.
Example:- ZnO + C--------Zn + CO
NOTE:- The hydrogen is gaining oxygen and being oxidised or one reactant gets oxidised while the other gets reduced during a reaction . Such reaction are called oxidation reduction or redox reaction.
Example:-2Cu + O2----------2CuO
CORROSION:- It is slow eating process of metal in which outermost layer of metal is covered with unwanted material called corrode. It is said to corrode and this process is called corrosion. The surface of some metal, such as iron is corroded when they are expored to moist air for a long period of time.This phenomeneon is known as corrosion.
Note:- (i). corrosion is caused in case of iron is called rusting. It is form when oxygen combined with iron.
Example:- 3Fe + 2O2-------Fe3O4(Rust)
(ii). Silver object becomes black due to deposition of sulphur from atmosphere.
PREVENTION FROM CORROSION:-
(i). We can prevent the object from corrosion by painting.
(ii). By electroplating metals are prevented from corrosion. In this method a least reactive metal is coated on more reactive metal.
Example:- Nickle(Ni) is coated on Iron(Fe) greasing is the effective method to prevent from corrosion.
RANCIDITY:- When an oil containing food items are exposed to the atmosphere it starts bad smelling. This process is called rancidity. Rancidity of substance are caused due to the oxidation of fat present in food.
PREVENTING FROM RANCIDITY:-
(i). Oil containing foods are kept in air tight packets.
(ii). Nitrogen gas filled in the packets having food items.
(iii). Anti-oxident are used in fat containing food.
Example:- Melting of ice, boiling of water & glowing of electric bulb etc.
PROPERTIES OF PHYSICAL CHANGE:-
1. No new substanceare formed in physical change.
2. The physical change are temporary changes which can be reserved easily to form the original substances.
CHEMICAL CHANGE :- Those change in which new substances are formed, are called chemical change.
Example:- Burning of paper, rusting of iron, ripening of fruit, coocking of food etc.
PROPERTIES OF CHEMICAL CHANGE:-
1. Always a new substance is formed.
2. The chemical change are permanent change in which matter can't be converted into its original form.
3. Colour,nature,taste,etc are get change.
CAUSE OF CHEMICAL CHANGE(Chemical Reaction):- Chemical are found due to chemical reaction. A chemical reaction is the process in which two or more substance reacts with each other to produce a new substance.
CHEMICAL EQUATION:- The short term representation of a chemical reaction with help of symbols in the form of equation is called chemical equation.
METHOD TO WRITE A CHEMICAL EQUATION:-Chemical equation can be written by following method:-
1. Write the word equation for the given chemical equation.
2. Write the reactant on left and product on right side and place an arrow from left to right.
3. If more than one reactant or product are found than place (+)between them.
4. Write the symbol equation for word equation.
Example:- Hydrogen and Oxygen combined together to form water.
write chemical equation for the reaction.
(i)-making the word equation.
hydrogen+oxygen = water
H2+O2 = H2O
UNBALANCED EQQUATION:- The equation in which number of atom are unequal on both side of equation is called unbalanced equation.
BALANCED EQUATION:- The equation in which the number of atoms are equal on both side of equation is called balanced equation.
METHOD TO WRITE A BALANCED CHEMICAL EQUATION:-
Following method are applied to balanced a chemical equation:-
1. write the word equation and then symbol equation for the reaction.
2. count the number of atoms on bath side on chemical equation and then balanced the unequal number of atoms on both side.
3. balance those atoms firstly which have maximum number and then balance other atom.
4. write the physical condition of reactant and product.
Example:- Write the chemical equation when iron reacts with water to produce ironoxide, hydrogen gas.
Solve:-(i) write the word equation.
iron + water ------- ironoxide + hydrogen
(ii) write the symbol equation.
Fe + H2O--------Fe3O4 + H2
(iii) balancing the equation.
Element L.H.S R.H.S
Fe 1 3
H 2 2
O 1 4
(iv) to balance the O atom-----4*H2O
Fe + 4H2O--------Fe3o4 + H2
(v) to balance the Fe atom------3*Fe
3Fe + 4H2O-------Fe3O4 + H2
(vi) to balance H atom---------4*H2
3Fe + 4H2O-------Fe3O4 + 4H2
(vii) write the state.
3Fe(s) + 4H2O(g)-------Fe3O4(s) + 4H2(g)
TYPES OF CHEMICAL REACTION:-
Chemical reaction have following type :-
1. COMBINATION REACTION:- The reaction in which two or more substance combine together to produce a single product called combination reaction.
Example:- A + B ----- C
(i) burning of coal.
C(s) + O2(g) ---------CO2(g)
2. EXOTHERMIC CHEMICAL REACTION:-Reaction in which heat is released along with the formation of products are called exothermic chemical reaction.
Example:-Burning of natural gas.
CH4(g) + 2O2-----CO2(g) + 2H2O(g)
3. ENDOTHERMIC REATION:- Reaction in which energy is absorbed are known as endothermic reaction.
3. DECOMPOSITION REACTION:- The reaction in which a reactant is broken down into two or more part are called decomposition reaction.
Example:-AB------A + B
CaCO3 + CaO + CO2
DECOMPOSION REACTION HAVE FOLLOWIN TYPE:-
(a). THERMAL DECOMPOSITION REACTION:- When decomposition reaction takes place due to the effect of temperater then the reaction is known as thermal decomposition reaction .
Example:- 2AgBr------2Ag + Br2
(b). PHOTO CHEMICAL DECOMPOSITION REACTION:- When a substance broken down into two or more substance in the presence of sunlight is called photo chemical decomposition reaction.
2AgClsunlight------2Ag + Cl2
NOTE:- The reaction is used in black and white photography.
(c). ELECTRIC DECOMPOSITION REACTION:- This type of decomposition reaction takes place due to the effect of electricity.
Example:- 2H2OacidH+---------2H2 + O2
4. DISPLACEMENT REACTION:- The reaction in which one atom of an element takes place the the position of other atom in chemical compound is called displacement reaction.
Example:-Zn + CuSO4---------ZnSO4 + Cu
5. DOUBLE DISPLACEMENT REACTION:- The reaction inwhich any atom is exchange between two chemical substance are called double displacement reaction.
Example:- Na2SO4 + BaCl2---------BaSO4 + 2NaCl
6. OXIDATION REACTION:- The reaction in which oxygen is combined to substance is called oxidation reaction.
Example:- C + O2--------CO2
7. REDUCTION REACTION:- The reaction in which oxygen released from the substance is called reduction reaction.
Example:- ZnO + C--------Zn + CO
NOTE:- The hydrogen is gaining oxygen and being oxidised or one reactant gets oxidised while the other gets reduced during a reaction . Such reaction are called oxidation reduction or redox reaction.
Example:-2Cu + O2----------2CuO
CORROSION:- It is slow eating process of metal in which outermost layer of metal is covered with unwanted material called corrode. It is said to corrode and this process is called corrosion. The surface of some metal, such as iron is corroded when they are expored to moist air for a long period of time.This phenomeneon is known as corrosion.
Note:- (i). corrosion is caused in case of iron is called rusting. It is form when oxygen combined with iron.
Example:- 3Fe + 2O2-------Fe3O4(Rust)
(ii). Silver object becomes black due to deposition of sulphur from atmosphere.
PREVENTION FROM CORROSION:-
(i). We can prevent the object from corrosion by painting.
(ii). By electroplating metals are prevented from corrosion. In this method a least reactive metal is coated on more reactive metal.
Example:- Nickle(Ni) is coated on Iron(Fe) greasing is the effective method to prevent from corrosion.
RANCIDITY:- When an oil containing food items are exposed to the atmosphere it starts bad smelling. This process is called rancidity. Rancidity of substance are caused due to the oxidation of fat present in food.
PREVENTING FROM RANCIDITY:-
(i). Oil containing foods are kept in air tight packets.
(ii). Nitrogen gas filled in the packets having food items.
(iii). Anti-oxident are used in fat containing food.
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