Question

b. identify reaction type:

1. burning of magnesium ribbon
2. rusting of iron

c. activity:
observe any chemical change at home and write observations.

d. diagram work:
draw a labelled setup showing magnesium ribbon burning.

brain challenge & thinking zone

1. design a safety poster on responsible use of electricity.
2. explain how chemistry and electricity are connected in everyday life.
3. create a science crossword using important terms.

project work (any one)

1. prepare a working model of electric circuit or electric bell. ( for roll no. 21 to 28)
2. prepare a working model on respiratory system ( for roll no. 11 to 20)
3. prepare a model of periodic table ( for roll no. 1 to 10)

parent signature: ____ teacher signature: ____

Explanation:

🆕 New Concept Discovered: Chemical Reaction Types
How substances change into entirely new substances

Step 1: Identify Reaction Types (Section B)

To identify the reaction types, we look at what happens to the substances chemically:

1. Burning of magnesium ribbon: When magnesium burns in the presence of oxygen, it combines with oxygen to form magnesium oxide.

$$ 2\text{Mg} + \text{O}_2 ightarrow 2\text{MgO} $$

Because two reactants combine to form a single product, this is a Combination Reaction (specifically, a Combustion/Oxidation Reaction).

1. Rusting of iron: Iron reacts slowly with oxygen and moisture (water) in the air to form hydrated iron(III) oxide (rust).

$$ 4\text{Fe} + 3\text{O}_2 + 2x\text{H}_2\text{O} ightarrow 2\text{Fe}_2\text{O}_3 \cdot x\text{H}_2\text{O} $$

This is also a Combination Reaction (specifically, a slow Oxidation Reaction).

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Step 2: Describe a Home Chemical Change Activity (Section C)

A simple, safe chemical change you can observe at home is the reaction between baking soda and vinegar.

• Observation: When you mix a spoonful of baking soda (sodium bicarbonate) with a splash of vinegar (acetic acid) in a cup, it immediately begins to fizz and bubble vigorously, releasing carbon dioxide gas. The cup also feels slightly colder (an endothermic reaction).

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Step 3: Describe the Diagram Setup for Burning Magnesium (Section D)

To draw a labeled setup showing a magnesium ribbon burning, include the following components:

• Pair of tongs: Holding one end of the magnesium ribbon.
• Magnesium ribbon: Burning with a dazzling, brilliant white flame.
• Bunsen burner (or spirit lamp): Providing the flame to ignite the ribbon.
• Watch glass (or petri dish): Placed underneath to collect the white powder product, which is Magnesium Oxide (\(\text{MgO}\)).
• Safety Note: Wear safety goggles to protect your eyes from the bright UV light.

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Step 4: Answer Brain Challenge & Thinking Zone (Questions 1 & 2)

1. Safety Poster Ideas on Responsible Use of Electricity:

• Headline: "Stay Safe, Stay Connected!"
• Rule 1: Never touch electrical switches or appliances with wet hands (water conducts electricity).
• Rule 2: Do not overload electrical sockets with too many plugs.
• Rule 3: Keep electrical cords away from water sources and heat.
• Rule 4: Never pull a plug out by tugging on its cord; pull the plug itself.

1. Connection Between Chemistry and Electricity:

• Batteries: The devices we use to power our phones, laptops, and toys rely on chemical reactions inside them to generate electrical energy (electrochemistry).
• Power Generation: Burning fossil fuels (a chemical combustion reaction) is used to generate steam that spins turbines to produce electricity.

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Answer:

B. Identify Reaction Type:

1. Burning of magnesium ribbon: Combination Reaction (Oxidation / Combustion)
2. Rusting of iron: Combination Reaction (Oxidation / Corrosion)

C. Activity (Home Observation):

• Chemical Change: Mixing baking soda and vinegar.
• Observation: Vigorous bubbling and fizzing due to the rapid release of carbon dioxide gas (\(\text{CO}_2\)).

D. Diagram Work:

To draw the setup, sketch a hand holding a pair of tongs which grips a magnesium ribbon over a burner flame. Show a brilliant white light radiating from the burning tip, with white ash (magnesium oxide) falling into a watch glass placed below.

Brain Challenge & Thinking Zone:

1. Safety Poster Rules:

• Do not touch switches with wet hands.
• Do not overload sockets.
• Pull the plug, not the cord.

1. Chemistry & Electricity Connection: Batteries convert stored chemical energy into electrical energy to power everyday portable devices.