(a) Removal of Greasy Dirt by Soap

Soap is an amphiphilic compound, meaning it has both hydrophilic (water-attracting) and hydrophobic (water-repelling) properties. The structure of a soap molecule consists of a long hydrocarbon chain (hydrophobic tail) and a polar group (hydrophilic head). When soap is mixed with water, it forms micelles, which are spherical aggregates where the hydrophobic tails point inward, trapping oily dirt and grease, while the hydrophilic heads remain outward in contact with water.

When greasy dirt is present on a surface, the hydrophobic tail of the soap molecule interacts with the oil molecules, while the hydrophilic head interacts with water. This dual interaction allows the soap molecules to effectively emulsify the grease. As the soap is agitated or scrubbed, the micelles form, surrounding the greasy particles. The soap effectively encapsulates the dirt, allowing it to be suspended in the water.

Rinsing with water washes away the micelles along with the trapped grease, leaving the surface clean. This mechanism is why soap is effective in cleaning oily substances that water alone cannot remove, demonstrating the principle of “like dissolves like” where the non-polar grease interacts with the non-polar tail of the soap, facilitating removal through the action of water.

(b) Absolute Alcohol and Its Extraction from Rectified Spirit

Absolute alcohol, or anhydrous ethanol, is pure ethanol with no water content, typically above 99% purity. It is widely used in the chemical industry, laboratories, and as a solvent. Rectified spirit, on the other hand, is a mixture of approximately 95% ethanol and 5% water.

To obtain absolute alcohol from rectified spirit, fractional distillation is employed. This process takes advantage of the different boiling points of ethanol (78.37°C) and water (100°C). In a fractional distillation setup, the rectified spirit is heated in a distillation flask. As the mixture is heated, ethanol vaporizes first due to its lower boiling point.

The vapor rises through a fractional distillation column, which provides a surface for repeated condensation and vaporization. This process enhances the separation of ethanol from water. The vapor is then condensed back into liquid form in a condenser. The distillate collected will have a higher concentration of ethanol.

By carefully controlling the temperature and collecting the distillate, it is possible to achieve a product with greater than 99% ethanol purity. The remaining water can be further reduced by additional distillation or using drying agents, ensuring the production of absolute alcohol.

(अ) साबुन द्वारा तैलीय मैल को हटाने का वर्णन

साबुन एक ऐम्फीफिलिक यौगिक है, जिसमें एक हाइड्रोफिलिक (पानी में घुलने वाला) हिस्सा और एक हाइड्रोफोबिक (तैलीय) हिस्सा होता है। जब साबुन को पानी में मिलाया जाता है, तो इसके हाइड्रोफोबिक भाग तैलीय मैल या गंदगी के अणुओं से संलग्न हो जाते हैं, जबकि हाइड्रोफिलिक भाग पानी में घुल जाता है। इससे साबुन के अणु एक “माइसेल” बनाते हैं, जिसमें तैलीय मैल का केंद्र और पानी का बाहरी भाग होता है। जब हम इस मिश्रण को रगड़ते हैं, तो साबुन के अणु मैल को लपेट लेते हैं और उसे पानी में घोलकर धो देते हैं। इस प्रक्रिया से तैलीय मैल और गंदगी को आसानी से हटाया जा सकता है, जिससे सतह साफ हो जाती है।

(ब) ‘परिशुद्ध ऐल्कोहल’ और रेक्टिफाइड स्पिरिट में “प्रभाजी आसवन”

परिशुद्ध ऐल्कोहल, जिसे एथिल ऐल्कोहल या इथेनॉल भी कहते हैं, एक रंगहीन, ज्वलनशील तरल है जिसका उपयोग औषधि, रसायन, और पेय पदार्थों में होता है। रेक्टिफाइड स्पिरिट वह मिश्रण है जिसमें 95% एथिल ऐल्कोहल और 5% पानी होता है।

“प्रभाजी आसवन” विधि द्वारा परिशुद्ध ऐल्कोहल प्राप्त करने के लिए, पहले रेक्टिफाइड स्पिरिट को गर्म किया जाता है। जब यह मिश्रण उबलता है, तो एथिल ऐल्कोहल का वाष्प निकाला जाता है, क्योंकि इसका उबलने का तापमान पानी से कम होता है। फिर इस वाष्प को ठंडा करके संक्षिप्त किया जाता है, जिससे शुद्ध एथिल ऐल्कोहल प्राप्त होता है। इस प्रक्रिया में विभिन्न तापमानों पर भिन्न यौगिकों का वाष्पीकरण और संकुचन होता है, जो कि उच्च शुद्धता प्राप्त करने में मदद करता है।

Plastics are synthetic or semi-synthetic materials made from polymers, which are long chains of repeating molecular units. They are versatile, lightweight, and can be molded into various shapes, making them widely used in packaging, construction, electronics, and many other industries.

Thermoplastics are a type of plastic that becomes pliable or moldable upon heating and solidifies upon cooling. They can be reheated and reshaped multiple times without significant chemical change. This property makes them ideal for recycling. Common examples of thermoplastics include:

1. Polyethylene (PE): Used in plastic bags and bottles.
2.Polyvinyl Chloride (PVC): Used in pipes, wiring, and flooring.

On the other hand, thermosetting plastics are those that undergo a chemical change when heated, resulting in a hard and inflexible structure. Once set, they cannot be remolded or reheated, making them durable and resistant to deformation. Examples of thermosetting plastics include:

1. Epoxy Resin: Commonly used in adhesives, coatings, and composite materials.
2.Bakelite: Used in electrical insulators, kitchenware, and industrial applications.

The primary distinction lies in their thermal behavior: thermoplastics can be reprocessed, while thermosetting plastics are permanently fixed after the initial setting. This fundamental difference influences their applications and recycling potential, with thermoplastics being more versatile and thermosetting plastics being more stable and durable in high-temperature environments.