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Rapid Revision - Chemical Reaction and Equations (Prashant Kirad)

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1K views19 pages

Rapid Revision - Chemical Reaction and Equations (Prashant Kirad)

Uploaded by

Laxmi singh
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© © All Rights Reserved
Available Formats
Download as PDF, TXT or read online on Scribd
Download as pdf or txt
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- RAPID REVISION -

Chemical Reactions
and Equations
Rapid
Revision

First watch One Shot


Chemical Reaction:
The transformation of chemical substance into another chemical.
substance. e.g. Rusting of iron, the setting of milk into curd.

Chemical Equation: Representation of chemical reaction using


symbols and formulae of the substances

A+B→C+D
Reactant Product

Mg + O2 → MgO
Make equations more informative:
Physical states - solid (s), liquid(l), gas(g), aqueous solution (aq).
Concentration of acid - Concentrated (conc.) Dilute (dil.)
Heat changes - Reactant(s) -> Product(s) + Heat
Reactant(s) + Heat -> Product(s)
Conditions to yield products -
Kuch important terms:
Precipitate: is the insoluble solid which settles down after the
completion of the chemical reaction.

Exothermic reactions: The chemical reactions that release heat


energy.

Endothermic reactions: The chemical reactions in which heat energy


is absorbed.

Catalyst: A catalyst is a substance that speeds up a chemical


reaction, or lowers the temperature or pressure needed to start one,
without itself being consumed during the reaction. e.g. Formation of
ammonia (Haber’s Process) - Fe (+ve catalyst)
Characteristics of Chemical Reaction:
i. Change in Colour

ii. Change in temperature (heat is generated)

iii. Change in State: (i.e. from gas to liquid)

iv. Evolution of Gas:

v. Formation of Precipitate

vi. Endothermic reaction (photosynthesis also)

(digestion and
vi. Exothermic reaction
respiration also)
Balanced Chemical Equation:
number of atoms of each element in reactants = number of atoms of each
element in products
Law of Conservation of Mass: Mass of reactants = Mass of products
“ Mass is neither created nor destroyed in a chemical reaction. ”
Balancing ke
Balance these: questions bohut
important h!
Types of Chemical Reactions:
1.Combination Reaction:
Two or more reactants combine to form single products.

A + B → AB

Carbon The most effective way to test for CO2 is to bubble the gas through lime water,
dioxide Test which is a diluted solution of calcium hydroxide.

2.Decomposition Reaction:
A single reactant decomposes to form two or more products.

AB → A + B
Decomposition Reaction

Thermal Decomposition Photolytic Decomposition


(initiated by thermal energy) (initiated by absorbing energy from photons)

black and white photography

Electrolytic Decomposition
(initiated by electrical energy)

Hydrogen Hydrogen (cathode) will produce a popping sound when a burning candle is brought close.
Test Oxygen (anode) will make the flame of the candle burn brighter.
Anode orr cathode
kisse lenge yaad
rakhna!
3.Displacement Reaction
chemical reaction in which a more reactive element
displaces a less reactive element from its compound.

Single Displacement

A + BC → AC + B Double Displacement

AB + CD → AD + CB
Reactivity Series:

Secret trick to
remember
Magnesium ribbon burns with a dazzling white flame
and changes into a white powder (magnesium Oxide)

Take some lead nitrate solution in a A yellow precipitate of lead iodide forms, and the
test tube or beaker and add potassium solution changes color from colorless to yellow.
iodide solution

Take some zinc granules in a conical Bubbles of hydrogen gas will form around the zinc
flask and add sulfuric acid. metal. The reaction releases heat along with the gas.

Calcium oxide reacts vigorously with water to produce


slaked lime (calcium hydroxide), releasing a large
amount of heat.

Originally green 🡢 Color changes to white, then brown


(ferric oxide) 🡢 smell of burning sulfur.
Brown fumes of nitrogen dioxide gas are released,
oxygen also present, Yellow lead monoxide solid
remains🡢appears reddish-brown when hot and yellow
when cold.

White silver chloride turns grey in sunlight.

Deep blue color of the solution fades to light green, and


the iron nail becomes covered with a red-brown layer
of copper

A white precipitate will form.

Forms a black substance CuO. Hydrogen gas can be


passed over the CuO causing a reverse reaction.
Redox Reactions: Oxidation + Reduction

Oxidation: + oxygen or - hydrogen


Reduction: - oxygen or + hydrogen

Oxidizing agent: An oxidizing agent is a substance that causes oxidation by


accepting electrons; therefore, it gets reduced.

Reducing agent: A reducing agent is a substance that causes reduction by losing


electrons; therefore it gets oxidized.
Effects of oxidation in daily life:

Corrosion: metals are gradually destroyed by chemical reactions with


substances in their environment, such as moisture and acids. Examples:
Rusting of iron, Tarnishing of silver, Green coating on copper
Prevention: Coating metals with protective layers (e.g., paint or
galvanization) helps prevent direct exposure to oxygen and moisture,
reducing the risk of corrosion.

Silver develops a black coating after some time.


Ag + H 2 S Ag 2 S + H 2

Copper develops a green coating after some time.


Cu + H 2 O + CO2 + O 2 CuCO 3 .Cu(OH) 2
Effects of oxidation in daily life:

Rancidity: the spoilage of fats and oils in food, leading


to unpleasant taste and smell. Examples: Spoiled butter,
Old cooking oil, Stale chips
Prevention: Adding antioxidants, storing foods in
airtight containers, and refrigerating can help slow
down or prevent the oxidation process and,
consequently, rancidity

Class 10th
Phodenge!
[2021]

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