https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemical-reactions/x8bc8fb44369617ed:physical-and-chemical-changes/v/physical-changes 2025-02-13T17:59:34.347326855Z Physical changes Physical changes alter the appearance or state of matter without changing its identity. Whether bending copper wire, crushing salt, freezing water, or dissolving salt into water, the substances retain their original forms, like H₂O or NaCl. Understanding physical changes helps identify substances through properties like melting and boiling points, which are inherent and consistent across samples. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/d873dd6b-08cf-4f7e-8fc0-4d02e97127ad_1280_720_base.png Physical changes Physical changes alter the appearance or state of matter without changing its identity. Whether bending copper wire, crushing salt, freezing water, or dissolving salt into water, the substances retain their original forms, like H₂O or NaCl. Understanding physical changes helps identify substances through properties like melting and boiling points, which are inherent and consistent across samples. https://cdn.kastatic.org/ka-youtube-converted/jn-skkO5NNI.mp4/jn-skkO5NNI.mp4 318 Physical and chemical changes https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemical-reactions/x8bc8fb44369617ed:physical-and-chemical-changes/v/chemical-changes 2025-03-21T20:29:57.678923887Z Chemical changes A chemical change occurs when a substance transforms into one or more new substances with different properties. Chemical reactions often involve color changes, gas production, odor changes, precipitate formation, or energy changes like heat or light. Unlike physical changes, chemical changes alter a substance’s identity, making them key to understanding chemical properties. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/3665da2c-e708-41b0-a732-779264ca6d87_1280_720_base.png Chemical changes A chemical change occurs when a substance transforms into one or more new substances with different properties. Chemical reactions often involve color changes, gas production, odor changes, precipitate formation, or energy changes like heat or light. Unlike physical changes, chemical changes alter a substance’s identity, making them key to understanding chemical properties. https://cdn.kastatic.org/ka-youtube-converted/CT5CVpOVAoY.mp4/CT5CVpOVAoY.mp4 445 Physical and chemical changes https://www.khanacademy.org/science/ap-chemistry-beta/x2eef969c74e0d802:chemical-reactions/x2eef969c74e0d802:physical-and-chemical-changes/v/physical-and-chemical-changes-molecular-level 2021-04-11T18:24:03Z Physical and chemical changes Physical and chemical processes can be classified by the changes occurring on the molecular level. In general, chemical processes involve changes in chemical bonds, while physical processes involve changes only in intermolecular forces. Some processes do not fit neatly into one category: for example, when NaCl dissolves in water, ionic bonds are broken (suggesting a chemical process), but no new substances are formed (suggesting a physical process). Sal Khan video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Physical and chemical changes Physical and chemical processes can be classified by the changes occurring on the molecular level. In general, chemical processes involve changes in chemical bonds, while physical processes involve changes only in intermolecular forces. Some processes do not fit neatly into one category: for example, when NaCl dissolves in water, ionic bonds are broken (suggesting a chemical process), but no new substances are formed (suggesting a physical process). https://cdn.kastatic.org/ka-youtube-converted/3e8e0d1fWLk.mp4/3e8e0d1fWLk.mp4 414 Physical and chemical changes https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemical-reactions/x8bc8fb44369617ed:physical-and-chemical-changes/e/apply-chemical-changes 2026-04-29T07:20:45.495372596Z Apply: Chemical changes Apply your understanding of chemical changes and chemical reactions in this set of free, standards-aligned practice questions. donna fig exercise https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemical-reactions/x8bc8fb44369617ed:physical-and-chemical-changes/e/understand-chemical-changes 2026-04-29T07:20:45.495372596Z Understand: Chemical changes Check your understanding of chemical changes and chemical reactions in this set of free, standards-aligned practice questions. donna exercise https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemical-reactions/x8bc8fb44369617ed:physical-and-chemical-changes/v/physical-and-chemical-changes-changes-in-matter 2026-04-15T09:00:48.368849752Z Physical and Chemical Changes -Changes in Matter Physical and Chemical Changes Khan Academy Pakistan video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Physical and Chemical Changes -Changes in Matter Physical and Chemical Changes https://cdn.kastatic.org/ka-youtube-converted/mDUzuQxQzZM.mp4/mDUzuQxQzZM.mp4 207 Physical and chemical changes https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemical-reactions/x8bc8fb44369617ed:physical-and-chemical-changes/e/physical-and-chemical-changes-in 2026-04-08T00:54:09.631945657Z Physical and Chemical changes Let's practice! vibhor exercise https://www.khanacademy.org/science/ap-chemistry-beta/x2eef969c74e0d802:chemical-reactions/x2eef969c74e0d802:physical-and-chemical-changes/e/physical-and-chemical-changes 2021-04-29T07:55:30Z Physical and chemical changes Check your understanding of physical and chemical changes at the molecular level in this set of free practice questions designed for AP Chemistry students. exercise https://www.khanacademy.org/science/cambridge-o-level-chemistry-cie/x8bc8fb44369617ed:chemical-reactions/x8bc8fb44369617ed:physical-and-chemical-changes/a/chemical-properties-and-changes 2026-04-15T09:00:48.368849752Z Learn and try: Chemical properties and changes Learn how to identify chemical properties of substances and distinguish chemical changes from physical changes. Explore the signs that indicate a chemical reaction has occurred and how new substances with different properties are formed. article