Melting Point - Revision history

Jennifervo at 15:04, 16 April 2016

2016-04-16T15:04:57Z

← Older revision		Revision as of 11:04, 16 April 2016
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	===Melting Point Depression===		===Melting Point Depression===

	It is ~~likely that you or someone you know has, at one point, spread salt over his or her driveway before~~ the ~~onset~~ of a ~~cold front. Somehow, this greatly reduces the amount of ice that forms on the covered surfaces. This helpful winter trick occurs due to a phenomenon know as~~ melting point ~~depression~~. ~~While~~ a ~~much more in-depth explanation could be given, here is~~ a ~~easy way to think about~~. ~~When~~ a ~~liquid freezes~~, ~~the molecules are attempting to orient and pack themselves in~~ a ~~way so as~~ to ~~form~~ a solid. ~~If foreign particles are in the liquid, they will partially block the liquid particles from forming into a solid thereby lowering the freezing point~~ of the ~~liquid. To summarize, the melting point of a material will decrease when a foreign solute~~ is ~~added to~~ the ~~solution~~.		Melting-point depression is the lowering of a material’s melting point by adding solutes. A mixture containing solutes melts at a lower temperature and a larger temperature range than a pure compound. Added solutes disrupt the crystalline structure of a solid, so that a smaller amount of energy is required to break the bonds of a solid.

			An example of the phenomenon is salting one's driveway in the winter.

	See [[https://en.wikipedia.org/wiki/Freezing-point_depression Freezing-point Depression]] for a closer look on how this process occurs and the math behind calculating the change in melting point!		See [[https://en.wikipedia.org/wiki/Freezing-point_depression Freezing-point Depression]] for a closer look on how this process occurs and the math behind calculating the change in melting point!

Jennifervo at 14:59, 16 April 2016

2016-04-16T14:59:11Z

← Older revision		Revision as of 10:59, 16 April 2016
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	===Enthalpy of Fusion===		===Enthalpy of Fusion===

	The enthalpy of fusion (the heat of fusion) is the change in enthalpy due to change in heat energy. Enthalpy of fusion is the energy required to transition the solid to the liquid state without changing its temperature. This is because enthalpy of fusion is a latent heat, ~~therefore~~ the temperature does not change in this process. Therefore, the energy is not used to heat the substance, but to break the solid bonds.		The enthalpy of fusion (the heat of fusion) is the change in enthalpy due to change in heat energy. Enthalpy of fusion is the energy required to transition the solid to the liquid state without changing its temperature. This is because enthalpy of fusion is a latent heat, as such, the temperature does not change in this process. Therefore, the energy is not used to heat the substance, but to break the solid bonds.

	At the melting point, the change in Gibbs free energy of a substance is zero, but the enthalpy and the entropy of the material are increasing. Melting occurs when the Gibbs free energy of a liquid becomes lower than the energy for the solid of that material.		At the melting point, the change in Gibbs free energy of a substance is zero, but the enthalpy and the entropy of the material are increasing. Melting occurs when the Gibbs free energy of a liquid becomes lower than the energy for the solid of that material.

Jennifervo at 14:58, 16 April 2016

2016-04-16T14:58:05Z

← Older revision		Revision as of 10:58, 16 April 2016
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	===Physical Properties===		===Physical Properties===

	Physical properties are distinguished into two subgroups: intensive and extensive physical properties. Intensive properties are independent of the quantity of the material present where as extensive properties are ~~not~~. For example, the density of a material is an intensive property while the mass of a material is an extensive property.		Physical properties are distinguished into two subgroups: intensive and extensive physical properties. Intensive properties are independent of the quantity of the material present where as extensive properties are dependent. For example, the density of a material is an intensive property while the mass of a material is an extensive property.

	==Melting Point==		==Melting Point==
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	==History==		==History==

	The concept of melting points has been used for thousands of years, although only in the past few centuries have scientists developed an accurate way to pinpoint the temperature at which the phase transformation occurs.		The concept of melting points has been used for thousands of years, although only in the past few centuries have scientists developed an accurate way to pinpoint the temperature at which the phase transformation occurs.The earliest recorded discovery of a melting-point apparatus is attributed to a work published in 1823 by French chemist, Michel Chevreul, who used melting points in organic chemistry to characterize various fatty acids, waxes, and oils. However, this technique was not well known until 1832, when a famous paper was published by German scientists, Justus von Liebig and Friedrich Wöhler. The paper detailed the chemistry of the benzoyl radical and reported the melting point of benzamide. A year following the paper, Liebig reported the boiling point of liquid acetal and began the practice of reporting the physical properties until the procedure of reporting the compounds physical properties became standard. Lieberg’s collaboration with Wöhler regarding organic compound melting points later led to the formulation of the concept of isomerism by Berzelius in 1831.

			By the 1890s, new apparatuses were built to increase the accuracy and speed of recording melting/boiling points. Most of these devices were composed of a melting point capillary attached to the stem of a thermometer which was suspended in a long-necked, round-bottom flask filled a liquid with a high boiling point. These apparatuses were heated at the bottom of the flask using a Bunsen burner.


	== See also ==		== See also ==

Jennifervo at 14:56, 16 April 2016

2016-04-16T14:56:42Z

← Older revision		Revision as of 10:56, 16 April 2016
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	Edited by Jennifer Vo		Edited by Jennifer Vo

	The melting point of a material is ~~an intensive physical property that indicates~~ the temperature at which the ~~substance transforms from a~~ solid to a liquid ~~or vice versa~~.		The melting point of a material is the characteristic temperature in which the solid transitions to a liquid under a fixed pressure.

	==Properties of Matter==		==Properties of Matter==

	~~On the most basic level, there~~ are two types of properties of matter: chemical and physical properties. Chemical properties are classified as those that change when the substance or material undergoes a chemical reaction involving a fundamental change in the identity of the material. ~~On the other hand, a~~ physical property ~~involves only a change in appearance~~ of the material.		There are two types of properties of matter: chemical and physical properties. Chemical properties are classified as those that change when the substance or material undergoes a chemical reaction involving a fundamental change in the identity of the material. A physical property can be observed or measured without altering the composition of the material.

	For example, consider the boiling a pot of water to cook a bowl of spaghetti. After sometime, the water begins to boil and form a vapor (i.e. steam). The water that boils off as steam has undergone a physical change in appearance, thus we can consider the boiling point of a substance as a physical property.		For example, consider the boiling a pot of water to cook a bowl of spaghetti. After sometime, the water begins to boil and form a vapor (i.e. steam). The water that boils off as steam has undergone a physical change in appearance, thus we can consider the boiling point of a substance as a physical property.

Jennifervo at 14:55, 16 April 2016

2016-04-16T14:55:32Z

← Older revision		Revision as of 10:55, 16 April 2016
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	==Melting Point==		==Melting Point==

	~~As mentioned previously, the~~ melting point of a ~~substance indicates~~ the temperature at which the ~~phase transition from~~ solid to liquid ~~or liquid to solid occurs~~. ~~The~~ melting point of a ~~substance will~~ be the same ~~regardless of~~ the ~~amount~~ of the ~~material present thus making the~~ melting point ~~an intensive property. Most individuals are familiar with standard melting points of various substances such~~ as ~~water, ethanol, or nitrogen. This standard melting point refers~~ to the ~~temperature at which melting occurs at atmospheric pressure~~. ~~This knowledge~~ of ~~standard conditions is~~ often ~~very useful as most transformations~~ and ~~reactions will occur in a open environment (atmospheric pressure), although it is important to note that melting point is not independent~~ of ~~pressure. That is, water at~~ a ~~pressure of 10 atmospheres will melt at a very different temperature than water at standard pressure~~.		The melting point of a material is the characteristic temperature in which the solid transitions to a liquid under a fixed pressure. In theory, the melting point of a solid should be the same temperature as the freezing point of a liquid. It is difficult to heat the solid above its particular melting point, as the heat energy is used to convert the solid to a liquid. Because of this property, melting points are often used to identify chemical compounds and determine the purity of a sample.

	===Enthalpy of Fusion===		===Enthalpy of Fusion===

Jennifervo at 14:54, 16 April 2016

2016-04-16T14:54:15Z

← Older revision		Revision as of 10:54, 16 April 2016
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	Edited by Jennifer Vo		Edited by Jennifer Vo

	The melting point of a ~~materical~~ is the ~~characteristic~~ temperature in which the solid ~~transitions~~ to a liquid ~~under a fixed pressure. In theory, the melting point of a solid should be the same temperature as the freezing point of a liquid~~.		The melting point of a material is an intensive physical property that indicates the temperature at which the substance transforms from a solid to a liquid or vice versa.

	==Properties of Matter==		==Properties of Matter==

	~~There~~ are two types of properties of matter: chemical and physical properties. Chemical properties are classified as those that change when the substance or material undergoes a chemical reaction involving a fundamental change in the identity of the material. A physical property ~~can be observed and measured without altering the composition~~ of the ~~substance~~.		On the most basic level, there are two types of properties of matter: chemical and physical properties. Chemical properties are classified as those that change when the substance or material undergoes a chemical reaction involving a fundamental change in the identity of the material. On the other hand, a physical property involves only a change in appearance of the material.

	For example, consider the boiling a pot of water to cook a bowl of spaghetti. After sometime, the water begins to boil and form a vapor (i.e. steam). The water that boils off as steam has undergone a physical change in appearance, thus we can consider the boiling point of a substance as a physical property.		For example, consider the boiling a pot of water to cook a bowl of spaghetti. After sometime, the water begins to boil and form a vapor (i.e. steam). The water that boils off as steam has undergone a physical change in appearance, thus we can consider the boiling point of a substance as a physical property.
Line 18:		Line 18:
	==Melting Point==		==Melting Point==

	~~The~~ melting point of a ~~material is~~ the ~~characteristic~~ temperature in which the solid ~~transitions~~ to a liquid ~~under a fixed pressure~~. ~~In theory, the~~ melting point of a ~~solid should~~ be the same ~~temperature as~~ the ~~freezing~~ point of ~~a liquid~~. ~~It is difficult~~ to ~~heat~~ the ~~solid above its particular~~ melting ~~point~~, ~~as the heat energy~~ is ~~used~~ to ~~convert the solid to a liquid~~. ~~Because of this property~~, ~~melting points are often used to identify chemical compounds and determine the purity~~ of a ~~sample~~.		As mentioned previously, the melting point of a substance indicates the temperature at which the phase transition from solid to liquid or liquid to solid occurs. The melting point of a substance will be the same regardless of the amount of the material present thus making the melting point an intensive property. Most individuals are familiar with standard melting points of various substances such as water, ethanol, or nitrogen. This standard melting point refers to the temperature at which melting occurs at atmospheric pressure. This knowledge of standard conditions is often very useful as most transformations and reactions will occur in a open environment (atmospheric pressure), although it is important to note that melting point is not independent of pressure. That is, water at a pressure of 10 atmospheres will melt at a very different temperature than water at standard pressure.

	===Enthalpy of Fusion===		===Enthalpy of Fusion===
Line 80:		Line 80:
	==History==		==History==

	The concept of melting points has been used for thousands of years, although only in the past few centuries have scientists developed an accurate way to pinpoint the temperature at which the phase transformation occurs.The earliest recorded discovery of a melting-point apparatus is attributed to a work published in 1823 by French chemist, Michel Chevreul, who used melting points in organic chemistry to characterize various fatty acids, waxes, and oils. However, this technique was not well known until 1832, when a famous paper was published by German scientists, Justus von Liebig and Friedrich Wöhler. The paper detailed the chemistry of the benzoyl radical and reported the melting point of benzamide. A year following the paper, Liebig reported the boiling point of liquid acetal and began the practice of reporting the physical properties until the procedure of reporting the compounds physical properties became standard. Lieberg’s collaboration with Wöhler regarding organic compound melting points later led to the formulation of the concept of isomerism by Berzelius in 1831.		The concept of melting points has been used for thousands of years, although only in the past few centuries have scientists developed an accurate way to pinpoint the temperature at which the phase transformation occurs.

	By the 1890s, new apparatuses were built to increase the accuracy and speed of recording melting/boiling points. Most of these devices were composed of a melting point capillary attached to the stem of a thermometer which was suspended in a long-necked, round-bottom flask filled a liquid with a high boiling point. These apparatuses were heated at the bottom of the flask using a Bunsen burner.


	== See also ==		== See also ==
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	[[http://www.scienceiscool.org/solutions/fpdepression.html Galen Lew the Science Dude!]]		[[http://www.scienceiscool.org/solutions/fpdepression.html Galen Lew the Science Dude!]]

	~~[[http://www.che.uc.edu/jensen/W.%20B.%20Jensen/Reprints/155.%20Melting%20Points.pdf]]~~

	[[Category:Properties of Matter]]		[[Category:Properties of Matter]]

Jennifervo at 14:52, 16 April 2016

2016-04-16T14:52:49Z

← Older revision		Revision as of 10:52, 16 April 2016
Line 1:		Line 1:
	Claimed by Clayton Maike		Claimed by Clayton Maike
			Edited by Jennifer Vo

	The melting point of a ~~material~~ is ~~an intensive physical property that indicates~~ the temperature at which the ~~substance transforms from~~ a solid to a liquid ~~or vice versa~~.		The melting point of a materical is the characteristic temperature in which the solid transitions to a liquid under a fixed pressure. In theory, the melting point of a solid should be the same temperature as the freezing point of a liquid.

	==Properties of Matter==		==Properties of Matter==

	~~On the most basic level, there~~ are two types of properties of matter: chemical and physical properties. Chemical properties are classified as those that change when the substance or material undergoes a chemical reaction involving a fundamental change in the identity of the material. ~~On the other hand, a~~ physical property ~~involves only a change in appearance~~ of the ~~material~~.		There are two types of properties of matter: chemical and physical properties. Chemical properties are classified as those that change when the substance or material undergoes a chemical reaction involving a fundamental change in the identity of the material. A physical property can be observed and measured without altering the composition of the substance.

	For example, consider the boiling a pot of water to cook a bowl of spaghetti. After sometime, the water begins to boil and form a vapor (i.e. steam). The water that boils off as steam has undergone a physical change in appearance, thus we can consider the boiling point of a substance as a physical property.		For example, consider the boiling a pot of water to cook a bowl of spaghetti. After sometime, the water begins to boil and form a vapor (i.e. steam). The water that boils off as steam has undergone a physical change in appearance, thus we can consider the boiling point of a substance as a physical property.
Line 17:		Line 18:
	==Melting Point==		==Melting Point==

	~~As mentioned previously, the~~ melting point of a ~~substance indicates~~ the temperature at which the ~~phase transition from~~ solid to liquid ~~or liquid to solid occurs~~. ~~The~~ melting point of a ~~substance will~~ be the same ~~regardless of~~ the ~~amount~~ of the ~~material present thus making the~~ melting point ~~an intensive~~ property~~. Most individuals are familiar with standard~~ melting points of ~~various substances such as water, ethanol, or nitrogen~~. ~~This standard melting point refers~~ to the temperature ~~at which melting occurs at atmospheric pressure~~. This ~~knowledge~~ of ~~standard conditions~~ is ~~often very useful as most transformations and reactions will occur~~ in ~~a open environment (atmospheric pressure)~~, ~~although it~~ is ~~important~~ to ~~note that~~ melting point is ~~not independent~~ of ~~pressure~~. ~~That is, water at a pressure~~ of ~~10 atmospheres will melt at~~ a ~~very different temperature~~ than ~~water at standard pressure~~.		The melting point of a material is the characteristic temperature in which the solid transitions to a liquid under a fixed pressure. In theory, the melting point of a solid should be the same temperature as the freezing point of a liquid. It is difficult to heat the solid above its particular melting point, as the heat energy is used to convert the solid to a liquid. Because of this property, melting points are often used to identify chemical compounds and determine the purity of a sample.

			===Enthalpy of Fusion===

			The enthalpy of fusion (the heat of fusion) is the change in enthalpy due to change in heat energy. Enthalpy of fusion is the energy required to transition the solid to the liquid state without changing its temperature. This is because enthalpy of fusion is a latent heat, therefore the temperature does not change in this process. Therefore, the energy is not used to heat the substance, but to break the solid bonds.
			At the melting point, the change in Gibbs free energy of a substance is zero, but the enthalpy and the entropy of the material are increasing. Melting occurs when the Gibbs free energy of a liquid becomes lower than the energy for the solid of that material.


	===Clausius-Clapeyron Equation===		===Clausius-Clapeyron Equation===
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	==History==		==History==

	The concept of melting points has been used for thousands of years, although only in the past few centuries have scientists developed an accurate way to pinpoint the temperature at which the phase transformation occurs.		The concept of melting points has been used for thousands of years, although only in the past few centuries have scientists developed an accurate way to pinpoint the temperature at which the phase transformation occurs.The earliest recorded discovery of a melting-point apparatus is attributed to a work published in 1823 by French chemist, Michel Chevreul, who used melting points in organic chemistry to characterize various fatty acids, waxes, and oils. However, this technique was not well known until 1832, when a famous paper was published by German scientists, Justus von Liebig and Friedrich Wöhler. The paper detailed the chemistry of the benzoyl radical and reported the melting point of benzamide. A year following the paper, Liebig reported the boiling point of liquid acetal and began the practice of reporting the physical properties until the procedure of reporting the compounds physical properties became standard. Lieberg’s collaboration with Wöhler regarding organic compound melting points later led to the formulation of the concept of isomerism by Berzelius in 1831.

			By the 1890s, new apparatuses were built to increase the accuracy and speed of recording melting/boiling points. Most of these devices were composed of a melting point capillary attached to the stem of a thermometer which was suspended in a long-necked, round-bottom flask filled a liquid with a high boiling point. These apparatuses were heated at the bottom of the flask using a Bunsen burner.


	== See also ==		== See also ==
Line 94:		Line 104:

	[[http://www.scienceiscool.org/solutions/fpdepression.html Galen Lew the Science Dude!]]		[[http://www.scienceiscool.org/solutions/fpdepression.html Galen Lew the Science Dude!]]

			[[http://www.che.uc.edu/jensen/W.%20B.%20Jensen/Reprints/155.%20Melting%20Points.pdf]]

	[[Category:Properties of Matter]]		[[Category:Properties of Matter]]

Cmaike3: /* Clausius-Clapeyron Equation */

2015-12-01T21:02:10Z

Clausius-Clapeyron Equation

← Older revision		Revision as of 17:02, 1 December 2015
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	===Clausius-Clapeyron Equation===		===Clausius-Clapeyron Equation===

	The melting and boiling point of a substance is dependent upon the pressure. This relationship is modeled by the Clausius-Clapeyron equation.		The melting and boiling point of a substance is dependent upon the pressure. This relationship can be modeled by the Clausius-Clapeyron equation.

	It is written as:		It is written as:
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	where <math>H_F</math> is equal the enthalpy of fusion, which is equal to the amount of energy that must be taken out or put into the system per mole of material for the phase transformation to occur. R is the gas constant.		where <math>H_F</math> is equal the enthalpy of fusion, which is equal to the amount of energy that must be taken out or put into the system per mole of material for the phase transformation to occur. R is the gas constant.

	''Note: This equation should be used only in idealized situations as it does not include the temperature dependence of the heat of fusion. For this reason, there is some inaccuracies involved in this calculation.''		''Note: This equation should be used only in idealized situations as it does not include the temperature dependence of the heat of fusion. For this reason, there is some inaccuracies involved in this calculation.''

	===Melting Point Depression===		===Melting Point Depression===

Cmaike3: /* References */

2015-12-01T15:36:01Z

References

← Older revision		Revision as of 11:36, 1 December 2015
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	==References==		==References==

	[[http://chemwiki.ucdavis.edu/Analytical_Chemistry/Chemical_Reactions/Properties_of_Matter UCDavis ChemWiki Properties of Matter][[http://chemwiki.ucdavis.edu/Physical_Chemistry/Physical_Properties_of_Matter/Phases_of_Matter/Phase_Transitions/Phase_Transitions/Clausius-Clapeyron_Equation UCDavis ChemWiki Clausuis-Clapeyron]][[http://www.scienceiscool.org/solutions/fpdepression.html Galen Lew the Science Dude!]]		[[http://chemwiki.ucdavis.edu/Analytical_Chemistry/Chemical_Reactions/Properties_of_Matter UCDavis ChemWiki Properties of Matter]]

			[[http://chemwiki.ucdavis.edu/Physical_Chemistry/Physical_Properties_of_Matter/Phases_of_Matter/Phase_Transitions/Phase_Transitions/Clausius-Clapeyron_Equation UCDavis ChemWiki Clausuis-Clapeyron]]

			[[http://www.scienceiscool.org/solutions/fpdepression.html Galen Lew the Science Dude!]]

	[[Category:Properties of Matter]]		[[Category:Properties of Matter]]

Cmaike3: /* References */

2015-12-01T15:35:13Z

References

← Older revision		Revision as of 11:35, 1 December 2015
Line 89:		Line 89:
	==References==		==References==

	[[http://chemwiki.ucdavis.edu/Analytical_Chemistry/Chemical_Reactions/Properties_of_Matter UCDavis ChemWiki Properties of Matter]]		[[http://chemwiki.ucdavis.edu/Analytical_Chemistry/Chemical_Reactions/Properties_of_Matter UCDavis ChemWiki Properties of Matter][[http://chemwiki.ucdavis.edu/Physical_Chemistry/Physical_Properties_of_Matter/Phases_of_Matter/Phase_Transitions/Phase_Transitions/Clausius-Clapeyron_Equation UCDavis ChemWiki Clausuis-Clapeyron]][[http://www.scienceiscool.org/solutions/fpdepression.html Galen Lew the Science Dude!]]

	[[http://chemwiki.ucdavis.edu/Physical_Chemistry/Physical_Properties_of_Matter/Phases_of_Matter/Phase_Transitions/Phase_Transitions/Clausius-Clapeyron_Equation UCDavis ChemWiki Clausuis-Clapeyron]]

	[[http://www.scienceiscool.org/solutions/fpdepression.html Galen Lew the Science Dude!]]

	[[Category:Properties of Matter]]		[[Category:Properties of Matter]]