Notes:- Chemical Reactions in the Real World The process by which iron turns into iron oxide is known as iron rusting. Something happens when iron comes into contact with oxygen and water. This process resembles a type of corrosion that occurs regularly in the natural world. Prevention of Rusting: i. By Painting ii. By Oiling and greasing iii. By Chromium plating iv. By Galvanizing v. By Alloying Metallic Oxides The formation of metal oxides is an example of chemical changes. They are formed by the reaction of oxygen in the air. - Burning of Magnesium ribbon: - 2Mg + O2 → 2MgO - The product formed is the oxide of magnesium, which is in the form of ash. It does not look anything like the magnesium ribbon used for burning. Reaction of metallic oxides with water ● The reaction of metal oxides with water forms metal hydroxides. ● For example, dissolving Magnesium oxide in water by stirring the ash very well with water. ● MgO + H2O → Mg(OH)2 ● The product formed is basic in nature and turns red litmus paper → blue Observations that indicate a chemical change ● Heat or light is absorbed or given out during a chemical reaction. ● Production of sound ● Production of gases or precipitates ● Production of smell ● A colour change may occur Rusting ● When substances made of Iron are exposed to oxygen and moisture in the atmosphere, it forms a red layer, which is called rust. ● The formation of rust can be represented by the following reaction: ● 4Fe + 3O2 → 2Fe2O3 . The chemical formula for rust is Fe2O3 .nH2O. More the moisture in the air, the quicker the formation of rust. Crystallisation Crystallisation is the process of removing salts from their solution. It is a method of purification used to remove crystals from polluted materials or purify saltwater. It is a shift in the body. Reaction between baking soda and vinegar When a pinch of baking soda is added to vinegar, we hear a hissing sound and observe the formation of bubbles. - Vinegar (Acetic Acid) + Baking Soda (Sodium bicarbonate) → CO2 (Carbon dioxide) + Other products The carbon dioxide produced during the reaction of Vinegar and baking soda, when passed through lime water, gives calcium carbonate as follows: - CO2 + Ca(OH)2 (lime water) → Calcium Carbonate (CaCO3 ) + H2O - The calcium carbonate turns lime water milky. Galvanization Galvanization is the technique of applying zinc to the surface of iron to stop it from rusting. An illustration would be galvanised iron water pipes. Iron is used to make ships, and it is galvanised. Seawater contains salts, which accelerates the rusting process. Ships must therefore replace their iron bodies annually. Food Cooking: During cooking, complex carbohydrates, fats, and protein molecules are broken down into smaller ones. It's believed to be a process of breakdown. Food that has been cooked makes digestion easier than uncooked food. Organic Substance Decay: Microorganisms like fungus and bacteria produce enzymes, which disassemble complex chemical substances into their simpler parts. Another name for it is a breakdown process. Purified chemicals can be extracted from their solutions via crystallisation. Benefits of CBSE Class 7 Science Notes Chapter 6 See the following list of advantages for the Chapter 6 Class 7 Science Revision Notes. The revision notes for Class 7 Science Chapter 6 will serve as an excellent resource for students to enhance their comprehension and review of the chapter's key ideas. During the exam, students will gain greater confidence in their ability to answer even the trickiest questions from the chapter. As a result, exam tension and anxiety will be significantly decreased. Students can swiftly and effectively rewrite their chapters without sacrificing the calibre of their preparation thanks to the revision notes. Since the revision notes are condensed and cover a large number of chapters, students can review from them the day before the exam when time is at a premium. The revision materials are easily accessed by students in PDF format, allowing them to study at any time and from any location
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Notes:-
Chemical Reactions in the Real World
The process by which iron turns into iron oxide is known as iron rusting. Something happens
when iron comes into contact with oxygen and water. This process resembles a type of
corrosion that occurs regularly in the natural world.
Prevention of Rusting:
i. By Painting
ii. By Oiling and greasing
iii. By Chromium plating
iv. By Galvanizing
v. By Alloying
Metallic Oxides
The formation of metal oxides is an example of chemical changes. They are formed by the
reaction of oxygen in the air.
- Burning of Magnesium ribbon:
- 2Mg + O2 → 2MgO
- The product formed is the oxide of magnesium, which is in the form of ash. It does not look
anything like the magnesium ribbon used for burning.
Reaction of metallic oxides with water
● The reaction of metal oxides with water forms metal hydroxides.
● For example, dissolving Magnesium oxide in water by stirring the ash very well with
water.
● MgO + H2O → Mg(OH)2
● The product formed is basic in nature and turns red litmus paper → blue
Observations that indicate a chemical change
● Heat or light is absorbed or given out during a chemical reaction.
● Production of sound
● Production of gases or precipitates
● Production of smell
● A colour change may occur
Rusting
● When substances made of Iron are exposed to oxygen and moisture in the atmosphere,
it forms a red layer, which is called rust.
● The formation of rust can be represented by the following reaction:
● 4Fe + 3O2 → 2Fe2O3
. The chemical formula for rust is Fe2O3
.nH2O. More the moisture in
the air, the quicker the formation of rust.
Crystallisation
Crystallisation is the process of removing salts from their solution. It is a method of purification
used to remove crystals from polluted materials or purify saltwater. It is a shift in the body.
Reaction between baking soda and vinegar
When a pinch of baking soda is added to vinegar, we hear a hissing sound and observe the
formation of bubbles.
- Vinegar (Acetic Acid) + Baking Soda (Sodium bicarbonate) → CO2
(Carbon dioxide) + Other
products
The carbon dioxide produced during the reaction of Vinegar and baking soda, when passed
through lime water, gives calcium carbonate as follows:
- CO2 + Ca(OH)2
(lime water) → Calcium Carbonate (CaCO3
) + H2O
- The calcium carbonate turns lime water milky.
Galvanization
Galvanization is the technique of applying zinc to the surface of iron to stop it from rusting.
An illustration would be galvanised iron water pipes. Iron is used to make ships, and it is
galvanised. Seawater contains salts, which accelerates the rusting process. Ships must
therefore replace their iron bodies annually.
Food Cooking: During cooking, complex carbohydrates, fats, and protein molecules are broken
down into smaller ones.
It's believed to be a process of breakdown. Food that has been cooked makes digestion easier
than uncooked food.
Organic Substance Decay: Microorganisms like fungus and bacteria produce enzymes, which
disassemble complex chemical substances into their simpler parts. Another name for it is a
breakdown process.
Purified chemicals can be extracted from their solutions via crystallisation.
Benefits of CBSE Class 7 Science Notes Chapter 6
See the following list of advantages for the Chapter 6 Class 7 Science Revision Notes.
The revision notes for Class 7 Science Chapter 6 will serve as an excellent resource for
students to enhance their comprehension and review of the chapter's key ideas.
During the exam, students will gain greater confidence in their ability to answer even the
trickiest questions from the chapter.
As a result, exam tension and anxiety will be significantly decreased.
Students can swiftly and effectively rewrite their chapters without sacrificing the calibre of their
preparation thanks to the revision notes.
Since the revision notes are condensed and cover a large number of chapters, students can
review from them the day before the exam when time is at a premium.
The revision materials are easily accessed by students in PDF format, allowing them to study at
any time and from any location
MAM PLEASE AAJ ACID BASES AND SALTS LARWA DO SUNDAY KE DIN PLEASE (Vote for Ch - Acid , Bases and salts)
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Neutralization. When acid and base is react with each other 😊
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