{"id":175695,"date":"2025-11-04T14:40:00","date_gmt":"2025-11-04T11:40:00","guid":{"rendered":"https:\/\/bukvaved.top\/v-chjom-raznica-mezhdu-fizicheskim-javleniem-i-himicheskoj-reakciej\/"},"modified":"2026-10-28T14:29:45","modified_gmt":"2026-10-28T11:29:45","slug":"what-is-the-difference-between-a-physical-phenomenon-and-a-chemical-reaction","status":"publish","type":"post","link":"https:\/\/bukvaved.top\/en\/v-chjom-raznica-mezhdu-fizicheskim-javleniem-i-himicheskoj-reakciej\/","title":{"rendered":"What is the difference between a physical phenomenon and a chemical reaction?"},"content":{"rendered":"<p><strong>A physical phenomenon changes only the physical properties of a substance (shape, state of aggregation, degree of fragmentation), whereas a chemical reaction creates new substances with different properties.<\/strong> Melting ice remains water, while burning wood produces ash, carbon dioxide, and water vapor. This single criterion\u2014whether a new substance has been created\u2014determines most school assignments.<\/p>\n<p> To sum it up<\/p>\n<ul>\n<li> <strong>Physical phenomenon<\/strong> : the same substance but in a different form (e.g. melting, evaporation, cracking, dissolution).<\/li>\n<li> <strong>Chemical reaction<\/strong> : new substances are formed (eg burning, rusting, baking a cake).<\/li>\n<li> The reaction is often accompanied by symptoms: color change, gas release, sediment, exposure to light, heat, odor.<\/li>\n<li> Reversibility is more of a guideline than a definitive criterion; what matters is the creation of a new substance.<\/li>\n<\/ul>\n<h2> Physical Phenomena - Definition and Examples<\/h2>\n<p> <strong>Physical phenomenon<\/strong> (physical change) is a transformation in which only the physical properties of a substance change, without the formation of new elements or chemical compounds. The particles remain the same\u2014only their arrangement, the distances between them, and the shape and size of the substance&#039;s particles change.<\/p>\n<p> Examples of physical phenomena:<\/p>\n<ul>\n<li> <strong>Changes in the state of aggregation of a substance<\/strong> \u2013 melting of ice, solidification of water, evaporation, condensation on glass, sublimation of iodine.<\/li>\n<li> <strong>Shape changes and fragmentation<\/strong> - cutting paper, grinding coffee, crushing sugar, bending wire, breaking glass.<\/li>\n<li> <strong>Dissolution<\/strong> sugar or salt in water (after the water evaporates, the substance again takes on a crystalline form).<\/li>\n<li> <strong>Mixing and separating mixtures<\/strong> \u2013 filtration, distillation, separation of iron filings using a magnet.<\/li>\n<li> thermal expansion, light bulb glow, magnetization.<\/li>\n<\/ul>\n<h2> Chemical Reaction - Definition and Examples<\/h2>\n<p> <strong>Chemical reaction<\/strong> (chemical change) is a process in which one substance - <strong>reagents<\/strong> - turns into something else <strong>- products<\/strong> \u2014 with different properties. Bonds between atoms are broken and re-formed. Atoms do not disappear or appear out of nowhere, so the mass of reactants is equal to the mass of products (the law of conservation of mass).<\/p>\n<p> Examples of chemical reactions from everyday life:<\/p>\n<ul>\n<li> <strong>combustion<\/strong> - firewood, gas in the stove, paraffin in the candle, magnesium tape,<\/li>\n<li> <strong>Rusting of iron<\/strong> \u2013 iron reacts with oxygen and water.<\/li>\n<li> <strong>Baking and frying<\/strong> \u2013 baking a cake, coagulating egg whites, caramelizing sugar.<\/li>\n<li> <strong>biological processes<\/strong> \u2013 souring of milk, fermentation, photosynthesis, digestion.<\/li>\n<li> <strong>\u00ab&quot;Kitchen&quot; reactions<\/strong> \u2013 baking soda with vinegar (gas is released \u2013 carbon dioxide).<\/li>\n<\/ul>\n<h2> Comparative table of physical phenomena and chemical reactions.<\/h2>\n<table>\n<tbody>\n<thead>\n<tr>\n<th> Characteristic<\/th>\n<th> Physical phenomenon<\/th>\n<th> Chemical reaction<\/th>\n<\/tr>\n<\/thead>\n<\/tbody>\n<tbody>\n<tr>\n<td> <strong>New substances<\/strong><\/td>\n<td> They don&#039;t arise<\/td>\n<td> They appear<\/td>\n<\/tr>\n<tr>\n<td> <strong>What is changing?<\/strong><\/td>\n<td> Physical properties (state of matter, form, fragmentation)<\/td>\n<td> Composition and chemical properties<\/td>\n<\/tr>\n<tr>\n<td> <strong>Chemical bonds in molecules<\/strong><\/td>\n<td> No changes<\/td>\n<td> Stolen, but something new created.<\/td>\n<\/tr>\n<tr>\n<td> <strong>Record<\/strong><\/td>\n<td> Verbal description, for example, water (singular) \u2192 water (verb)<\/td>\n<td> Reaction equation, for example: C + O\u2082 \u2192 CO\u2082<\/td>\n<\/tr>\n<tr>\n<td> <strong>Reversibility<\/strong><\/td>\n<td> Often it&#039;s easy (ice \u2194 water)<\/td>\n<td> This is often difficult or impossible under normal circumstances.<\/td>\n<\/tr>\n<tr>\n<td> <strong>Typical examples<\/strong><\/td>\n<td> Melting, evaporating, cutting, dissolving sugar<\/td>\n<td> Burning, rusting, baking, souring of milk<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2> Signs of a chemical reaction \u2013 how to recognize them?<\/h2>\n<p> The formation of new substances is often accompanied by visible consequences. The most common ones are <strong>symptoms of a chemical reaction<\/strong> include:<\/p>\n<ul>\n<li> change in color (for example, darkening of a cut apple, appearance of rust).<\/li>\n<li> The release of gas that was not there before (bubbles from the reaction of baking soda with vinegar).<\/li>\n<li> formation of a precipitate in solution,<\/li>\n<li> release or absorption of heat,<\/li>\n<li> radiation of light (flame),<\/li>\n<li> The appearance of a new odor (for example, the smell of rancid oil).<\/li>\n<\/ul>\n<p> Beware of pitfalls. These symptoms alone are not proof. Boiling water also &quot;releases gas&quot; (water vapor), and melting absorbs heat\u2014these are physical phenomena. However, some reactions occur without visible symptoms. The decisive question is always the same: <strong>was a new substance formed?<\/strong><\/p>\n<h2> Is reversibility enough to distinguish them?<\/h2>\n<p> Many textbooks and cheat sheets use the principle that &quot;physical phenomena are reversible, chemical ones are not.&quot; This is a good guideline, but not a rule. Broken glass can&#039;t be easily mended, but breaking is a physical phenomenon: glass remains glass. On the other hand, there are reversible reactions, such as the decomposition and regeneration of certain compounds under changing conditions.<\/p>\n<p> A good example of this difference is the classic school experiment with <strong>iron and sulfur<\/strong> . When the powders are mixed, a mixture is formed\u2014iron filings can be extracted with a magnet (a physical phenomenon). When the mixture is heated, a reaction occurs that forms iron sulfide\u2014a new substance that cannot be separated with a magnet.<\/p>\n<h2> How to distinguish a physical phenomenon from a chemical reaction?<\/h2>\n<p> A simple procedure helps to solve the problem of &quot;assigning transformations&quot;:<\/p>\n<ol>\n<li> Ask <strong>, what does the substance consist of after the change<\/strong> . If it remains the same (water, sugar, paper) \u2013 it is a physical phenomenon.<\/li>\n<li> Check if it is possible <strong>write a reaction equation<\/strong> with different formulas on either side of the arrow. If so, it&#039;s a chemical reaction.<\/li>\n<li> Pay attention to symptoms (color, gas, sediment), but consider them as clues, not proof.<\/li>\n<li> Be careful with kitchen examples: boiling water is physics, but boiling an egg is chemistry (the egg white curdles irreversibly).<\/li>\n<\/ol>\n<p> In practice, both types of transformations often occur simultaneously. A burning candle is a good example: the paraffin first melts and evaporates (a physical phenomenon), and its vapors burn in the flame (a chemical reaction).<\/p>\n<h2> Frequently Asked Questions (FAQ)<\/h2>\n<p> <strong>Is dissolving sugar in water a chemical reaction?<\/strong><\/p>\n<p> In school chemistry, dissolving sugar or salt in water is considered a physical phenomenon. No new substance is formed\u2014the sugar or salt can be regenerated by evaporating the water.<\/p>\n<p> <strong>Is melting ice a physical phenomenon?<\/strong><\/p>\n<p> Yes. Ice and water are the same substance (H2O) in different states of aggregation. Only the arrangement of the molecules changes, not their structure.<\/p>\n<p> <strong>Is rusting a physical phenomenon or a chemical reaction?<\/strong><\/p>\n<p> Rusting is a chemical reaction. Iron reacts with oxygen and water, and the resulting rust has properties different from those of metal: it is brittle, porous, and a different color.<\/p>\n<p> <strong>Is a burning candle a physical phenomenon?<\/strong><\/p>\n<p> Both processes occur within it. The melting and evaporation of paraffin are physical phenomena, while the combustion of its vapors in a flame is a chemical reaction.<\/p>\n<p> <strong>What are the symptoms of a chemical reaction?<\/strong><\/p>\n<p> The most common signs include color change, gas evolution, sediment formation, heat release or absorption, exposure to light, and the development of a new odor. However, the defining criterion is the formation of a new substance.<\/p>\n<h2> See also<\/h2>\n<ul>\n<li> What is the difference between boiling and evaporation?<\/li>\n<li> What is the difference between a metal and a non-metal?<\/li>\n<li> What is the difference between mineral water and spring water?<\/li>\n<li> What is the difference between a vitamin and a provitamin?<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>A physical phenomenon changes only the physical properties of a substance (shape, state of aggregation, degree of fragmentation), whereas a chemical reaction creates new substances with<\/p>","protected":false},"author":1,"featured_media":175696,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[67,20],"tags":[70],"class_list":["post-175695","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-vopros-otvet","category-fakty","tag-chem-otlichaetsya"],"_links":{"self":[{"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/posts\/175695","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/comments?post=175695"}],"version-history":[{"count":1,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/posts\/175695\/revisions"}],"predecessor-version":[{"id":175697,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/posts\/175695\/revisions\/175697"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/media\/175696"}],"wp:attachment":[{"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/media?parent=175695"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/categories?post=175695"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/tags?post=175695"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}