For StudentsFor ParentsFor SchoolsSuccess StoriesOutcomesAI 1. Matter : (i) Anything which has mass and occupies some space is called matter (ii) Solid, liquid and gas are not the substances but three different states of the same substance. 2. Characteristics of particles of matter : (i) The states of a substance differ with respect to interparticle spaces and intermolecular forces. (ii) The arrangement of the constituent particles is most ordered in solid state. It is comparatively less in the liquid state while in the gaseous state, the particles can move quite freely. 3. States of matter : (i) Solids have fixed shape and definite volume. (ii) Liquids have definite volume but no fixed shape. (iii) Gases have neither fixed shape nor definite volume. (iv) The kinetic energy of particles is maximum in the gaseous state and minimum in the solid state. (v) The diffusion of the gases varies inversely as the square root of their densities. (vi) Lighter gases can move upwards and heavier gases can move downwards. (vii) Gases can be compressed to a large extent on applying pressure. 4. Interconversion of states of matter : (i) The three states of a substance are interconvertible, i.e., one state can be converted into the other and vice-versa. (ii) At the melting point, a solid starts melting and the temperature remains the same till the whole of it has melted. (iii) At the boiling point, a liquid starts boiling and the temperature remains the same till the entire liquid has changed to vapours. (iv) Vapours represent the gaseous state of a substance which is a liquid at room temperature. (v) Latent heat of fusion is the amount of heat energy needed to convert one kg of a solid into liquid state at its melting point without any rise in temperature. (vi) Latent heat of vaporisation is the amount of heat energy needed to convert 1 kg of a liquid into vapour state at its boiling point without any rise in temperature. (vii) Kelvin temperature is more than Celsius temperature by 273°. (viii) A substance is said to be in the solid state if its melting point is above the room temperature under normal pressure. (ix) A substance is said to be in the liquid state if its melting point is below the room temperature under normal pressure. (x) A substance is said to be in the gaseous state if its boiling point is below the room temperature under normal pressure. (xi) The standard room temperature is 25°C or 298 K. (xii) Change of pressure and temperature have opposing effects on the physical state of a substance. (xiii) A gas can be liquefied by either decreasing the temperature or by increasing the pressure or both. (xiv) Normal atmospheric pressure is one atmosphere and it decreases at higher altitudes. (xv) Solid carbon dioxide is known as dry ice. 5. Evaporation : (i) Evaporation is a surface phenomenon whereas boiling is a bulk phenomenon. (ii) Increase in the surface area increases the evaporation of a liquid. (iii) We perspire more on a humid day than on a dry day. (iv) Low boiling liquids evaporate faster than high boiling liquids. (v) Cooling is caused during evaporation and not during boiling. Sublimation is converting a substance directly from the solid to the gaseous state of matter without passing through the liquid state. Watch this video. Water ice changes to liquid water at its melting point, whereas liquid water changes to water vapour at its boiling point. Isn’t it? Watch this video to lear... Do you know the pressure is directly proportional to the boiling point of the water? Watch this video to learn more about this concept in detail. As you watch the video, you may recall how ice helps us on a hot summer day to cool down and how a steaming cup of tea is enjoyed during a rainy day. How does matter, in its different states, occupy space? If you ever asked yourself, you're in the right place! Watch this informative video to learn about it. Materials do change their states from solid to liquid to gas. But what exactly happens when they undergo this change? Watch this video to find out. {"appState":{"pageLoadApiCallsStatus":true},"articleState":{"article":{"headers":{"creationTime":"2016-03-26T17:23:38+00:00","modifiedTime":"2016-03-26T17:23:38+00:00","timestamp":"2022-09-14T18:06:54+00:00"},"data":{"breadcrumbs":[{"name":"Academics & The Arts","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33662"},"slug":"academics-the-arts","categoryId":33662},{"name":"Science","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33756"},"slug":"science","categoryId":33756},{"name":"Physics","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33769"},"slug":"physics","categoryId":33769}],"title":"Why Temperature Remains Constant during a Phase Change","strippedTitle":"why temperature remains constant during a phase change","slug":"why-temperature-remains-constant-during-a-phase-change","canonicalUrl":"","seo":{"metaDescription":"Thanks to physics, we know that p hase changes occur when materials change state, going from liquid to solid (as when water freezes), solid to liquid (as when r","noIndex":0,"noFollow":0},"content":"<p>Thanks to physics, we know that <i>p</i><i>hase changes</i> occur when materials change state, going from liquid to solid (as when water freezes), solid to liquid (as when rocks melt into lava), liquid to gas (as when you boil water for tea), and so on. When the material in question changes to a new state — liquid, solid, or gas (you can also factor in a fourth state: plasma, a superheated gas-like state) — some heat goes into or comes out of the process without changing the temperature.</p>\n<p class=\"TechnicalStuff\">You can even have solids that turn directly into gas. As dry ice (frozen carbon dioxide gas) gets warmer, it turns into carbon dioxide gas. This process is called <i>sublimation.</i></p>\n<p>Imagine you’re calmly drinking your lemonade at an outdoor garden party. You grab some ice to cool your lemonade, and the mixture in your glass is now half ice, half lemonade (which you can assume has the same specific heat as water), with a temperature of exactly 0 degrees Celsius.</p>\n<p>As you hold the glass and watch the action, the ice begins to melt — but the contents of the glass don’t change temperature. Why? The heat (thermal energy) going into the glass from the outside air is melting the ice, not warming the mixture up. So does this make the equation for heat energy </p>\n<img src=\"https://sg.cdnki.com/why-the-temperature-remains-constant-during-sublimation---aHR0cHM6Ly93d3cuZHVtbWllcy5jb20vd3AtY29udGVudC91cGxvYWRzLzMzMDA0NC5pbWFnZTAucG5n.webp\" width=\"81\" height=\"27\" alt=\"image0.png\"/>\n<p>useless? Not at all — it just means that the equation doesn’t apply for a phase change.</p>\n<p>If you graph the heat added to a system versus the system’s temperature, the graph usually slopes upward; adding heat increases temperature. However, the graph levels out during phase changes, because on a molecular level, making a substance change state requires energy. After all the material has changed state, the temperature can rise again.</p>\n<div class=\"imageBlock\" style=\"width:535px;\"><img src=\"https://sg.cdnki.com/why-the-temperature-remains-constant-during-sublimation---aHR0cHM6Ly93d3cuZHVtbWllcy5jb20vd3AtY29udGVudC91cGxvYWRzLzMzMDA0NS5pbWFnZTEuanBn.webp\" width=\"535\" height=\"384\" alt=\"Phase changes of water.\"/><div class=\"imageCaption\">Phase changes of water.</div></div>\n<p>Imagine that someone has taken a bag of ice and thoughtlessly put it on the stove. Before it hit the stove, the ice was at a temperature below freezing (–5 degrees Celsius), but being on the stove is about to change that. You can see the change taking place in graph form in the figure. (The specific heat of ice is around 2.1 x 10<sup>3</sup> J/kg-C)</p>\n<img src=\"https://sg.cdnki.com/why-the-temperature-remains-constant-during-sublimation---aHR0cHM6Ly93d3cuZHVtbWllcy5jb20vd3AtY29udGVudC91cGxvYWRzLzMzMDA0Ni5pbWFnZTIucG5n.webp\" width=\"476\" height=\"45\" alt=\"image2.png\"/>\n<p>that the temperature of the ice will increase linearly as you add more heat to it, as you see in the graph.</p>\n<p>However, when the ice reaches 0 degrees Celsius, the ice is getting too warm to hold its solid state, and it begins to melt, undergoing a phase change. When you melt ice, breaking up the crystalline ice structure requires energy, and the energy needed to melt the ice is supplied as heat. That’s why the graph in the figure levels off in the middle — the ice is melting. You need heat to make the ice change phase to water, so even though the stove adds heat, the temperature of the ice doesn’t change as it melts.</p>\n<p>As you watch the bag of ice on the stove, however, you note that all the ice eventually melts into water. Because the stove is still adding heat, the temperature begins to rise, which you see in the figure. The stove adds more and more heat to the water, and in time, the water starts to bubble. “Aha,” you think. “Another phase change.” And you’re right: The water is boiling and becoming steam. The bag holding the ice seems pretty resilient, and it expands while the water turns to steam.</p>\n<p>You measure the temperature of the water. Fascinating — although the water boils, turning into steam, the temperature doesn’t change. Once again, you need to add heat to incite a phase change — this time from water to steam. You can see in the figure that as you add heat, the water boils, but the temperature of that water doesn’t change.</p>\n<p>What’s going to happen next, as the bag swells to an enormous volume? You never get to find out, because the bag finally explodes. </p>","description":"<p>Thanks to physics, we know that <i>p</i><i>hase changes</i> occur when materials change state, going from liquid to solid (as when water freezes), solid to liquid (as when rocks melt into lava), liquid to gas (as when you boil water for tea), and so on. When the material in question changes to a new state — liquid, solid, or gas (you can also factor in a fourth state: plasma, a superheated gas-like state) — some heat goes into or comes out of the process without changing the temperature.</p>\n<p class=\"TechnicalStuff\">You can even have solids that turn directly into gas. As dry ice (frozen carbon dioxide gas) gets warmer, it turns into carbon dioxide gas. This process is called <i>sublimation.</i></p>\n<p>Imagine you’re calmly drinking your lemonade at an outdoor garden party. You grab some ice to cool your lemonade, and the mixture in your glass is now half ice, half lemonade (which you can assume has the same specific heat as water), with a temperature of exactly 0 degrees Celsius.</p>\n<p>As you hold the glass and watch the action, the ice begins to melt — but the contents of the glass don’t change temperature. Why? The heat (thermal energy) going into the glass from the outside air is melting the ice, not warming the mixture up. So does this make the equation for heat energy </p>\n<img src=\"https://www.dummies.com/wp-content/uploads/330044.image0.png\" width=\"81\" height=\"27\" alt=\"image0.png\"/>\n<p>useless? Not at all — it just means that the equation doesn’t apply for a phase change.</p>\n<p>If you graph the heat added to a system versus the system’s temperature, the graph usually slopes upward; adding heat increases temperature. However, the graph levels out during phase changes, because on a molecular level, making a substance change state requires energy. After all the material has changed state, the temperature can rise again.</p>\n<div class=\"imageBlock\" style=\"width:535px;\"><img src=\"https://www.dummies.com/wp-content/uploads/330045.image1.jpg\" width=\"535\" height=\"384\" alt=\"Phase changes of water.\"/><div class=\"imageCaption\">Phase changes of water.</div></div>\n<p>Imagine that someone has taken a bag of ice and thoughtlessly put it on the stove. Before it hit the stove, the ice was at a temperature below freezing (–5 degrees Celsius), but being on the stove is about to change that. You can see the change taking place in graph form in the figure. (The specific heat of ice is around 2.1 x 10<sup>3</sup> J/kg-C)</p>\n<img src=\"https://www.dummies.com/wp-content/uploads/330046.image2.png\" width=\"476\" height=\"45\" alt=\"image2.png\"/>\n<p>that the temperature of the ice will increase linearly as you add more heat to it, as you see in the graph.</p>\n<p>However, when the ice reaches 0 degrees Celsius, the ice is getting too warm to hold its solid state, and it begins to melt, undergoing a phase change. When you melt ice, breaking up the crystalline ice structure requires energy, and the energy needed to melt the ice is supplied as heat. That’s why the graph in the figure levels off in the middle — the ice is melting. You need heat to make the ice change phase to water, so even though the stove adds heat, the temperature of the ice doesn’t change as it melts.</p>\n<p>As you watch the bag of ice on the stove, however, you note that all the ice eventually melts into water. Because the stove is still adding heat, the temperature begins to rise, which you see in the figure. The stove adds more and more heat to the water, and in time, the water starts to bubble. “Aha,” you think. “Another phase change.” And you’re right: The water is boiling and becoming steam. The bag holding the ice seems pretty resilient, and it expands while the water turns to steam.</p>\n<p>You measure the temperature of the water. Fascinating — although the water boils, turning into steam, the temperature doesn’t change. Once again, you need to add heat to incite a phase change — this time from water to steam. You can see in the figure that as you add heat, the water boils, but the temperature of that water doesn’t change.</p>\n<p>What’s going to happen next, as the bag swells to an enormous volume? You never get to find out, because the bag finally explodes. </p>","blurb":"","authors":[{"authorId":8967,"name":"Steven Holzner","slug":"steven-holzner","description":" <p><b> Dr. Steven Holzner</b> has written more than 40 books about physics and programming. He was a contributing editor at <i>PC Magazine</i> and was on the faculty at both MIT and Cornell. He has authored Dummies titles including <i>Physics For Dummies</i> and <i>Physics Essentials For Dummies.</i> Dr. Holzner received his PhD at Cornell.</p> ","hasArticle":false,"_links":{"self":"https://dummies-api.dummies.com/v2/authors/8967"}}],"primaryCategoryTaxonomy":{"categoryId":33769,"title":"Physics","slug":"physics","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33769"}},"secondaryCategoryTaxonomy":{"categoryId":0,"title":null,"slug":null,"_links":null},"tertiaryCategoryTaxonomy":{"categoryId":0,"title":null,"slug":null,"_links":null},"trendingArticles":null,"inThisArticle":[],"relatedArticles":{"fromBook":[{"articleId":208460,"title":"Physics I For Dummies Cheat Sheet","slug":"physics-i-for-dummies-cheat-sheet","categoryList":["academics-the-arts","science","physics"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/208460"}},{"articleId":184049,"title":"A List of Physics Constants","slug":"a-list-of-physics-constants","categoryList":["academics-the-arts","science","physics"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/184049"}},{"articleId":184043,"title":"Physics Equations and Formulas","slug":"physics-equations-and-formulas","categoryList":["academics-the-arts","science","physics"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/184043"}},{"articleId":174308,"title":"Calculating Tangential Velocity on a Curve","slug":"calculating-tangential-velocity-on-a-curve","categoryList":["academics-the-arts","science","physics"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/174308"}},{"articleId":174307,"title":"Flowing from Hot to Cold: The Second Law of Thermodynamics","slug":"flowing-from-hot-to-cold-the-second-law-of-thermodynamics","categoryList":["academics-the-arts","science","physics"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/174307"}}],"fromCategory":[{"articleId":209405,"title":"String Theory For Dummies Cheat Sheet","slug":"string-theory-for-dummies-cheat-sheet","categoryList":["academics-the-arts","science","physics"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/209405"}},{"articleId":209012,"title":"Physics II For Dummies Cheat Sheet","slug":"physics-ii-for-dummies-cheat-sheet","categoryList":["academics-the-arts","science","physics"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/209012"}},{"articleId":208592,"title":"Thermodynamics For Dummies Cheat Sheet","slug":"thermodynamics-for-dummies-cheat-sheet","categoryList":["academics-the-arts","science","physics"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/208592"}},{"articleId":208578,"title":"Optics For Dummies Cheat Sheet","slug":"optics-for-dummies-cheat-sheet","categoryList":["academics-the-arts","science","physics"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/208578"}},{"articleId":208460,"title":"Physics I For Dummies Cheat Sheet","slug":"physics-i-for-dummies-cheat-sheet","categoryList":["academics-the-arts","science","physics"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/208460"}}]},"hasRelatedBookFromSearch":false,"relatedBook":{"bookId":282467,"slug":"physics-i-for-dummies","isbn":"9781119872221","categoryList":["academics-the-arts","science","physics"],"amazon":{"default":"https://www.amazon.com/gp/product/1119872227/ref=as_li_tl?ie=UTF8&tag=wiley01-20","ca":"https://www.amazon.ca/gp/product/1119872227/ref=as_li_tl?ie=UTF8&tag=wiley01-20","indigo_ca":"http://www.tkqlhce.com/click-9208661-13710633?url=https://www.chapters.indigo.ca/en-ca/books/product/1119872227-item.html&cjsku=978111945484","gb":"https://www.amazon.co.uk/gp/product/1119872227/ref=as_li_tl?ie=UTF8&tag=wiley01-20","de":"https://www.amazon.de/gp/product/1119872227/ref=as_li_tl?ie=UTF8&tag=wiley01-20"},"image":{"src":"https://www.dummies.com/wp-content/uploads/9781119872221-203x255.jpg","width":203,"height":255},"title":"Physics I For Dummies","testBankPinActivationLink":"","bookOutOfPrint":true,"authorsInfo":"<p><b> Dr. <b data-author-id=\"8967\">Steven Holzner</b></b> has written more than 40 books about physics and programming. 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He has authored Dummies titles including <i>Physics For Dummies</i> and <i>Physics Essentials For Dummies.</i> Dr. Holzner received his PhD at Cornell.</p> ","hasArticle":false,"_links":{"self":"https://dummies-api.dummies.com/v2/authors/8967"}}],"_links":{"self":"https://dummies-api.dummies.com/v2/books/"}},"collections":[],"articleAds":{"footerAd":"<div class=\"du-ad-region row\" id=\"article_page_adhesion_ad\"><div class=\"du-ad-unit col-md-12\" data-slot-id=\"article_page_adhesion_ad\" data-refreshed=\"false\" \r\n data-target = \"[{"key":"cat","values":["academics-the-arts","science","physics"]},{"key":"isbn","values":["9781119872221"]}]\" id=\"du-slot-6322183e108f5\"></div></div>","rightAd":"<div class=\"du-ad-region row\" id=\"article_page_right_ad\"><div class=\"du-ad-unit col-md-12\" data-slot-id=\"article_page_right_ad\" data-refreshed=\"false\" \r\n data-target = \"[{"key":"cat","values":["academics-the-arts","science","physics"]},{"key":"isbn","values":["9781119872221"]}]\" 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Thanks to physics, we know that phase changes occur when materials change state, going from liquid to solid (as when water freezes), solid to liquid (as when rocks melt into lava), liquid to gas (as when you boil water for tea), and so on. When the material in question changes to a new state — liquid, solid, or gas (you can also factor in a fourth state: plasma, a superheated gas-like state) — some heat goes into or comes out of the process without changing the temperature. You can even have solids that turn directly into gas. As dry ice (frozen carbon dioxide gas) gets warmer, it turns into carbon dioxide gas. This process is called sublimation. Imagine you’re calmly drinking your lemonade at an outdoor garden party. You grab some ice to cool your lemonade, and the mixture in your glass is now half ice, half lemonade (which you can assume has the same specific heat as water), with a temperature of exactly 0 degrees Celsius. As you hold the glass and watch the action, the ice begins to melt — but the contents of the glass don’t change temperature. Why? The heat (thermal energy) going into the glass from the outside air is melting the ice, not warming the mixture up. So does this make the equation for heat energy useless? Not at all — it just means that the equation doesn’t apply for a phase change. If you graph the heat added to a system versus the system’s temperature, the graph usually slopes upward; adding heat increases temperature. However, the graph levels out during phase changes, because on a molecular level, making a substance change state requires energy. After all the material has changed state, the temperature can rise again. Imagine that someone has taken a bag of ice and thoughtlessly put it on the stove. Before it hit the stove, the ice was at a temperature below freezing (–5 degrees Celsius), but being on the stove is about to change that. You can see the change taking place in graph form in the figure. (The specific heat of ice is around 2.1 x 103 J/kg-C) that the temperature of the ice will increase linearly as you add more heat to it, as you see in the graph. However, when the ice reaches 0 degrees Celsius, the ice is getting too warm to hold its solid state, and it begins to melt, undergoing a phase change. When you melt ice, breaking up the crystalline ice structure requires energy, and the energy needed to melt the ice is supplied as heat. That’s why the graph in the figure levels off in the middle — the ice is melting. You need heat to make the ice change phase to water, so even though the stove adds heat, the temperature of the ice doesn’t change as it melts. As you watch the bag of ice on the stove, however, you note that all the ice eventually melts into water. Because the stove is still adding heat, the temperature begins to rise, which you see in the figure. The stove adds more and more heat to the water, and in time, the water starts to bubble. “Aha,” you think. “Another phase change.” And you’re right: The water is boiling and becoming steam. The bag holding the ice seems pretty resilient, and it expands while the water turns to steam. You measure the temperature of the water. Fascinating — although the water boils, turning into steam, the temperature doesn’t change. Once again, you need to add heat to incite a phase change — this time from water to steam. You can see in the figure that as you add heat, the water boils, but the temperature of that water doesn’t change. What’s going to happen next, as the bag swells to an enormous volume? You never get to find out, because the bag finally explodes. |