CHEMICAL
REACTIONS AND EQUATIONS
1. https://www.youtube.com/watch?v=NRCn8z8gb1w&t=3s
2. https://youtu.be/eJXL0IrbtqE?t=10
3. https://youtu.be/8m6RtOpqvtU?t=8
1. https://www.youtube.com/watch?v=NRCn8z8gb1w&t=3s
2. https://youtu.be/eJXL0IrbtqE?t=10
3. https://youtu.be/8m6RtOpqvtU?t=8
Daily Life Experiences of Chemical Reactions:
1. Curdling Of Milk
2. Rusting of Metal
3. Fermentation of Fruits/ Grapes
4. Digestion of Food in the body
5. Cellular Respiration
ACTIVITY -1:
Clean a Magnesium ribbon with sand paper,burn it keeping away from eyes. We observe, dazzling white flames coming out and formation of white powder (MgO) [ watch video here ]
Mg + O2 è 2MgO
ACTIVITY-2:
Take Lead Nitrate solution in a test tube and add Potassium Iodide solution in it, we observe formation of yellow precipitate.
PRECIPITATE: It is a solid formed by a change in a solution due to some chemical reaction or change in temperature (that decreased the solubility of the solid) [ watch video here ]
ACTIVITY-3:
Take Zinc granules in a boiling test tube, add dilute sulphuric or hydrochloric acid to it. We observe, small bubbles around Zinc granules ( Hydrogen gas liberation). Touch the flask, it will be warmer than before, hence it is an exothermic reaction (heat produced).
[ watch video here ]
So, we conclude from above three reactions that, if in any reaction we observe:
1. Change in State
2. Change in Colour
3. Change in Temperature
4. Production of Gas
then it is a CHEMICAL REACTION...
Chemical Equation
1. Curdling Of Milk
2. Rusting of Metal
3. Fermentation of Fruits/ Grapes
4. Digestion of Food in the body
5. Cellular Respiration
ACTIVITY -1:
Clean a Magnesium ribbon with sand paper,burn it keeping away from eyes. We observe, dazzling white flames coming out and formation of white powder (MgO) [ watch video here ]
Mg + O2 è 2MgO
 |
| ( BURNING OF MAGNESIUM RIBBON ) |
Take Lead Nitrate solution in a test tube and add Potassium Iodide solution in it, we observe formation of yellow precipitate.
PRECIPITATE: It is a solid formed by a change in a solution due to some chemical reaction or change in temperature (that decreased the solubility of the solid) [ watch video here ]
ACTIVITY-3:
Take Zinc granules in a boiling test tube, add dilute sulphuric or hydrochloric acid to it. We observe, small bubbles around Zinc granules ( Hydrogen gas liberation). Touch the flask, it will be warmer than before, hence it is an exothermic reaction (heat produced).
[ watch video here ]
So, we conclude from above three reactions that, if in any reaction we observe:
1. Change in State
2. Change in Colour
3. Change in Temperature
4. Production of Gas
then it is a CHEMICAL REACTION...
Chemical Equation
Chemical Equation represents a chemical reaction in short either in Words or symbolically.
How to write a Balanced Chemical Equation
- An Equation must follow "LAW OF CONSERVATION OF MASS".
- In other words, The Numbers of ATOMS of every chemical remains SAME before or after the Reaction.
STEP-WISE WRITING:
STEP-1:- First, write word equation for the reaction.
Zinc + Sulphuric Acid è Zinc Sulphate + Hydrogen
STEP -2: Write chemical equivalents using symbols and molecular formula.
STEPS TO BALANCE:
STEP-1:- First, write word equation for the reaction.
Zinc + Sulphuric Acid è Zinc Sulphate + Hydrogen
STEP -2: Write chemical equivalents using symbols and molecular formula.
Zn + H2SO4
è ZnSO4 + H2
STEP 3: Compare the numbers of atoms of each type, on either side of arrow (LHS must be equal to RHS for every atom)
ELEMENT
|
REACTANT (LHS)
|
PRODUCT (RHS)
|
Zn
|
1
|
1
|
H
|
2
|
2
|
S
|
1
|
1
|
O
|
4
|
4
|
(ITS A BALANCED REACTION )
HOW TO BALANCE AN UNBALANCED EQUATION ?
Fe + H2O è Fe3O4 + H2
ELEMENT
|
REACTANT (LHS)
|
PRODUCT (RHS)
|
Fe
|
1
|
3
|
H
|
2
|
2
|
O
|
1
|
4
|
STEPS TO BALANCE:
1. Start
with a compound having maximum number of atoms in it. (here Fe3O4)
and the element OXYGEN ( LHS- 01 & RHS-04).
2. To balance OXYGEN,
2. To balance OXYGEN,
Atoms of Oxygen
|
In Reactants (LHS)
|
In Products (RHS)
|
INITIALLY
|
1 (H2O)
|
2 (Fe3O4)
|
After Balancing
|
1 X 4
|
4
|
- So, Fe + 4 H2O è Fe3O4 + H2
33. ONLY COEFFICIENT CAN BE CHANGED NOT THE SUBSCRIPT)
H2O
can’t be written as H2O4 or (H2O)4
4. Now, to Balance HYDROGEN
Atoms of Hydrogen
|
In Reactants (LHS)
|
In Products (RHS)
|
INITIALLY
|
8 (4 H2O )
|
2 (H2 )
|
After Balancing
|
8
|
2 X 4 = 8
|
S SO, Fe + 4 H2O è Fe3O4 + 4 H2
5. TO BALANCE IRON (Fe):
Atoms of IRON
|
In Reactants (LHS)
|
In Products (RHS)
|
INITIALLY
|
1 ( Fe)
|
3 (Fe3O4
)
|
After Balancing
|
I X 3 = 3
|
3
|
So, , 3 Fe + 4 H2O è Fe3O4 + 4 H2 (BALANCED)
Finally Check :
ELEMENT
|
REACTANT (LHS)
|
PRODUCT (RHS)
|
Fe
|
3
|
3
|
H
|
8
|
8
|
O
|
4
|
4
|
[ VIDEO: BASICS OF CHEMICAL EQUATIONS ]
Chemical Reactions – Types
( 1) Combination reaction.
(synthesis reaction.)- [ VIDEO ]
Reaction in which two or more reactants combine to form a single product.
A reaction in which heat is released along with the formation of PRODUCT.
A
reaction in which heat is utilised for the formation of PRODUCT.
(synthesis reaction.)- [ VIDEO ]
Reaction in which two or more reactants combine to form a single product.
EXOTHERMIC REACTIONS:
A reaction in which heat is released along with the formation of PRODUCT.
ENDOTHERMIC REACTIONS:
( 2)
Decomposition
reaction.- [ VIDEO ]
Reaction in which one reactant breaks into two or more products.
ACTIVITY-5:
Heat Ferrous Sulphate crystals in Dry Boiling Tube. Note the change in colour & odour.
(A) THERMAL DECOMPOSITION:
(ACTIVITY: 6)
HEAT LEAD NITRATE POWDER IN BURNING TUBE AND OBSERVE BROWN FUMES COMING OUT.
(B) ELECTROLYTIC DECOMPOSITION:
ACTIVITY:1.7- Electrolysis of Water
(C) PHOTO-CHEMICAL DECOMPOSITION:
ACTIVITY-8:
Expose Silver Chloride to Sunlight for sometime.
Reaction in which one reactant breaks into two or more products.
ACTIVITY-5:
Heat Ferrous Sulphate crystals in Dry Boiling Tube. Note the change in colour & odour.
(A) THERMAL DECOMPOSITION:
(ACTIVITY: 6)
HEAT LEAD NITRATE POWDER IN BURNING TUBE AND OBSERVE BROWN FUMES COMING OUT.
(B) ELECTROLYTIC DECOMPOSITION:
ACTIVITY:1.7- Electrolysis of Water
(C) PHOTO-CHEMICAL DECOMPOSITION:
ACTIVITY-8:
Expose Silver Chloride to Sunlight for sometime.
 |
| (SILVER CHLORIDE: BEFORE (LEFT) & AFTER (RIGHT) |
 |
| (PHOTOLYSIS OF SILVER BROMIDE) |
(3)
Displacement reaction.- [ VIDEO ]
Reactions in which one metal displaces the other metal from its compound in aqueous solution.
Put some iron nails in Copper Sulphate solution for sometime. Observe the colour of the solution before and after the activity.
Reactions in which one metal displaces the other metal from its compound in aqueous solution.
ACTIVITY: 9-
Put some iron nails in Copper Sulphate solution for sometime. Observe the colour of the solution before and after the activity.
(4)
Double displacement
reaction.- [ VIDEO ]
A double displacement reaction, also known as a double replacement reaction or metathesis, is a type of chemical reaction where two compounds react, and the positive ions (cation) and the negative ions (anion) of the two reactants switch places, forming two new compounds or products.
A double displacement reaction, also known as a double replacement reaction or metathesis, is a type of chemical reaction where two compounds react, and the positive ions (cation) and the negative ions (anion) of the two reactants switch places, forming two new compounds or products.
ACTIVITY: 10-
When barium chloride combines with sodium sulphate in the form of their aqueous solutions, a white precipitate of barium sulphate is formed which is insoluble in water.
(5)
Oxidation and
reduction reaction (REDOX).- [ VIDEO ]
Reactions where oxidation states of atom are changed, most often one component undergo oxidation and another reduction.
or
An oxidation-reduction (redox) reaction is a type of chemical reaction that involves a transfer of electrons between two species. An oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron.
ACTIVITY-11:
Heating copper powder change colour to brown.
COMMON REDOX REACTIONS IN LIFE:
Reactions where oxidation states of atom are changed, most often one component undergo oxidation and another reduction.
or
An oxidation-reduction (redox) reaction is a type of chemical reaction that involves a transfer of electrons between two species. An oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron.
ACTIVITY-11:
Heating copper powder change colour to brown.
COMMON REDOX REACTIONS IN LIFE:
(An oxidation
reaction which causes rusting of iron.)
Definition:
Attacking of metals by surrounding substances like air,moisture,acids. For eg. Rusting of iron, a green coating on copper, a black coating on silver.
Attacking of metals by surrounding substances like air,moisture,acids. For eg. Rusting of iron, a green coating on copper, a black coating on silver.
 |
| (IRON RUST) |
 |
| (COPPER RUST) |
Methods of preventing corrosion are
paint, oiling. Greasing, galvanizing, anodizing, electroplating and alloying.
 |
| (METAL PRIMER) |
 |
| (Hot-Dip GALVANIZATION) |
 |
| (GREASING) |
RANCIDITY: [ VIDEO ]
Changing of the
taste and smell of fatty foods due to oxidation of fats is called Rancidity.
 |
| (RANCIDITY- TYPES) |
 |
| (FAT Hydrolysis) |
 |
| (CELL Oxidation) |
Methods to prevent
Rancidity:
(1)
Keep food in air tight containers.
(2)
Add antioxidants to the food.
(3)
Flush the packed foods with gases like nitrogen.
CHEMISTRY/SCIENCE TRICKS :
1. https://www.youtube.com/watch?v=8vyboVwyzfU
2. https://www.youtube.com/watch?v=uLp0NhNszQU
Courtesy Google images for Pictures and You tube for Video links.
CHEMISTRY/SCIENCE TRICKS :
1. https://www.youtube.com/watch?v=8vyboVwyzfU
2. https://www.youtube.com/watch?v=uLp0NhNszQU
Courtesy Google images for Pictures and You tube for Video links.
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