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আমাদের চারপাশের পরিবর্তন| অধ্যায়-৭ | পর্ব-২ | সপ্তম শ্রেণির বিজ্ঞান অনুসন্ধানী পাঠ | Class 7 Science

Technique Easy Education・19 minutes read

Chemical reactions can lead to irreversible changes, creating new substances like carbon dioxide from chalk and vinegar. Reversible changes, seen in processes like melting or boiling, allow substances to return to their original state without forming new compounds. Recycling plastic and paper is essential to reduce waste, conserve resources, and prevent environmental pollution.

Insights

  • Chemical reactions can result in reversible changes, allowing substances to return to their original state, or irreversible changes that permanently alter compounds, showcasing the distinction between altering the external state and creating new substances.
  • Recycling plastic and paper plays a vital role in reducing environmental waste, conserving natural resources, and preventing the accumulation of garbage, highlighting the importance of reusing materials to create a sustainable cycle of production and consumption.

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Recent questions

  • What are reversible changes in chemistry?

    Reversible changes in chemistry allow substances to return to their original state without creating new substances. Examples include melting, boiling, cooling, and dissolution. These changes involve altering the external state of a substance while maintaining its chemical composition intact.

  • How do irreversible changes differ from reversible changes in chemistry?

    Irreversible changes in chemistry permanently alter substances, typically through chemical reactions that create new compounds. Examples of irreversible changes include cooking, burning, or powdering substances. Unlike reversible changes, irreversible changes do not allow substances to return to their original state.

  • Why is recycling plastic important for the environment?

    Recycling plastic is crucial for reducing environmental waste, conserving natural resources, and preventing the accumulation of garbage in the environment. By collecting used plastic bottles, washing them in industrial facilities, remanufacturing them, and putting them back on the market, a cycle of reuse is created, reducing the need for new plastic production and minimizing plastic pollution.

  • How is paper recycled to reduce waste?

    Paper recycling involves mixing waste paper with water and chemicals to create a pulp that can be reshaped into new paper products through various methods. This process helps in reducing waste, conserving natural resources, and minimizing the environmental impact of paper production by reusing existing materials.

  • Can physical changes be reversible or irreversible?

    Physical changes, such as stretching a rubber band, can be either reversible or irreversible. Reversible physical changes involve altering the external state of a substance without creating new compounds, while irreversible physical changes permanently alter the structure of substances.

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Summary

00:00

Chemical Changes: Reversible vs Irreversible Processes

  • Today's lesson focuses on reversible and irreversible changes in chemistry.
  • Chemical reactions lead to chemical changes, altering the structure of compounds.
  • A simple test involves grinding chalk and adding vinegar to observe a chemical reaction.
  • The reaction produces carbon dioxide, with chalk being calcium carbonate and vinegar being acetic acid.
  • Reactions like this exemplify irreversible chemical changes.
  • Reversible changes allow substances to return to their original state, like melting ice or boiling water.
  • Examples of reversible processes include melting, boiling, cooling, and dissolution.
  • Reversible changes involve altering the external state without creating new substances.
  • Physical changes, like stretching a rubber band, can be reversible or irreversible.
  • Irreversible changes, such as cooking, burning, or powdering, permanently alter substances and are typically chemical changes.

17:44

Recycling Plastic and Paper for Sustainability

  • Plastic can be recycled or reused, allowing it to be melted and remanufactured into new plastic products by different manufacturers.
  • The process of recycling plastic involves collecting used plastic bottles, washing them in an industrial factory, remanufacturing them, and putting them back on the market, creating a cycle of reuse.
  • Recycling plastic is crucial to reduce environmental waste, conserve natural resources, and prevent the accumulation of garbage in the environment.
  • Paper can also be recycled by mixing waste paper with water and chemicals, creating a pulp that can be reshaped into new paper products through various methods, contributing to the reduction of waste and conservation of resources.
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