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Topic: Melting point


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In the News (Sun 19 Nov 17)

  
  Periodic Table : Periodic properties : Melting point: Definition
The melting point is the temperature at which the vapour pressure of the solid and the liquid are the same and the presssure totals one atmosphere.
Thus, the melting point of water is = 0°C = 273.15 K and the boiling point of water is = 100°C = 373.15 K
On the Fahrenheit scale (°F), the melting point of water = 32°F while the boiling point = 212°F. Therefore the degree size is different on the Fahrenheit scale with 180 Fahrenheit degrees = 100 centigrade degrees.
www.webelements.com /webelements/scholar/properties/definitions/melting-point.html   (279 words)

  
  The MSDS HyperGlossary: Freezing Point
The normal freezing point is the temperature at a substance melts (or freezes) at one atmosphere (760 torr = 760 mm Hg = 14.7 psi = 101.3 kPa) of pressure.
Melting points can be determined by visual inspection or by monitoring the temperature of the liquid with time.
Melting points may be lowered (depressed) by the addition of a soluble material to the solution.
www.ilpi.com /msds/ref/freezingpoint.html   (335 words)

  
  Melting point - Wikipedia, the free encyclopedia
The melting point of a solid is the temperature at which it changes state from solid to liquid.
Unlike the boiling point, the melting point is relatively insensitive to pressure.
The material with the highest known melting point at atmospheric pressure is graphite, with a melting point of 3948 kelvins.
en.wikipedia.org /wiki/Melting_point   (281 words)

  
 CHM 235L - Exp. 1 Melting Points
The melting point of the mixture will be identical to that of the known compound in the first instance or lowered and much broadened in the latter.
Melting point capillary tubes are placed (closed end down) in the slots directly in front of the thermometer and are viewed through the magnifying lens.
Determine the melting points of pure samples of cinnamic acid and urea as well as a 50-50 mixture of the two, and record the data in your lab notebook.
jan.ucc.nau.edu /~jkn/235L1-MeltingPoint.htm   (1659 words)

  
 CHM 230 Lab Manual Melting Point   (Site not responding. Last check: )
The freezing point of a liquid is the same temperature as the melting point of its solid.
If its melting point is the same as that of the unknown, it is likely that your unknown and the compound with which you mixed it are the same.
Melting Point of an Impure Substance Melting Point of a Mixture of (a) and (b) ___________________________oC III.
chemlab.pc.maricopa.edu /labbooks/meltingPoint.html   (2127 words)

  
 Melting Point Analysis   (Site not responding. Last check: )
Melting point analysis is one of the simplest and most useful techniques for the identification of a chemical substance.
When a melting point analysis is performed, a small amount of sample is first loaded into a melting point capillary tube, which is then heated in a melting point apparatus until melting is observed.
A melting point apparatus is an electrical device equipped with a thermometer, a magnifying glass, and heating block with which a hole has been drilled to allow a melting point capillary tube to be inserted.
www.chem.ubc.ca /courseware/123/tutorials/exp10A/meltpoint   (1401 words)

  
 AllRefer.com - melting point (Physics) - Encyclopedia   (Site not responding. Last check: )
melting point, temperature at which a substance changes its state from solid to liquid.
Under standard atmospheric pressure different pure crystalline solids will each melt at a different specific temperature; thus melting point is a characteristic of a substance and can be used to identify it.
The quantity of heat necessary to change one gram of any substance from solid to liquid at its melting point is known as its latent heat of fusion and differs for different substances.
reference.allrefer.com /encyclopedia/M/meltingp.html   (354 words)

  
 Melting Point
The melting point of a substance is the temperature at which the solid phase converts to the liquid phase under 1 atmosphere of pressure.
The melting point is one of a number of physical properties of a substance that is useful for characterizing (describing) and identifying the substance.
To measure the melting point of a substance, it is necessary somehow to gradually heat a small sample of the substance while monitoring its temperature with a thermometer.
www.wpi.edu /Academics/Depts/Chemistry/Courses/General/meltingpoint.html   (907 words)

  
 Melting Point Sample Preparation
The melting point (mp) is a physical property of a substance.
Melting points are often given in lab handbooks as single temperatures.
The melting point is found by slowly raising the temperature of a small sample of solid.
www.csi.edu /ip/physci/faculty/rex/MPMain.HTM   (318 words)

  
 The Importance of a Melting Point
The purpose of this laboratory exercise is to introduce the concept of the melting point of an organic compound as a first step in chemically identifying that compound.
With a pure substance, a melting point is the quickest and most accessible method for an organic chemist to confirm the identity of a compound (though in all fairness, NMR is the method of choice due to the proof of identity it provides as well as other information it gives).
Once the two pure melting points have been determined find a partner and together prepare 3 samples: one of 1:9 urea : cinnamic acid, one of 1:1 urea : cinnamic acid, and one of 9:1 urea : cinnamic acid.
www.owlnet.rice.edu /~chem215/MeltingPt.html   (958 words)

  
 Chemical Elements.com - Help
Melting Point- The melting point of any element is the temperature at which the element changes from a solid to a liquid or from a liquid to a solid.
The melting point of a substance is also the freezing point.
Boiling Point- The boiling point of any element is the temperature at which it changes from a liquid to a gas or from a gas to a liquid.
www.chemicalelements.com /sup/help.html   (1882 words)

  
 Instrument Business Outlook: Market profile: melting point.(Brief Article)@ HighBeam Research   (Site not responding. Last check: )
Melting point is a thermal property that can be used to identify a substance.
The degree of variation from its specific melting point can be used to calculate the amount of contamination present in a sample.
During the melting point process, a very small quantity of a crushed substance is heated slowly...
www.highbeam.com /library/doc0.asp?DOCID=1G1:87148218&refid=ip_encyclopedia_hf   (182 words)

  
 Physical Method of Organic Identification: Melting Point Determination   (Site not responding. Last check: )
The melting point of a compound is generally defined as the equilibrium of a compound between its solid and liquid phases/states.
The value of this method is that the purer the compound being melted, the sharper, or closer together, the melting range (remember to express the melting of a compound or mixture of compounds as a temperature range).
One point of necessity is that to obtain sharp melting point ranges, it is necessary to raise the temperature of the melting block s…l…o…w…l…y.
tooldoc.wncc.nevada.edu /melter.htm   (769 words)

  
 Chem 211 - Melting Point
Melting points may be run from 8 AM to 6PM Monday through Friday only.
The melting point for this compound and any other should really be called a melting range, since the crystals will never melt instantaneously.
When recording a melting point, the first temperature noted is the temperature at which you see the first drop of liquid.
www.wellesley.edu /Chemistry/chem211lab/Orgo_Lab_Manual/Appendix/Instruments/MeltingPoint/melting_point.html   (328 words)

  
 Measure Melting Point
The melting point of a pure substance is defined as the temperature at which the solid and liquid phases are at equilibrium at 1 atmosphere of pressure.
Melting points are used to identify a substance and assess their purity.
The melting point of a pure substance is a unique property of that substance.
www.kolias.com /science/meltingpoint.htm   (447 words)

  
 Melting Point, Freezing Point, Boiling Point
In theory, the melting point of a solid should be the same as the freezing point of the liquid.
When this solid melts, the sodium acetate dissolves in the water that was trapped in the crystal to form a solution.
Because it is difficult to heat solids to temperatures above their melting points, and because pure solids tend to melt over a very small temperature range, melting points are often used to help identify compounds.
chemed.chem.purdue.edu /genchem/topicreview/bp/ch14/melting.php   (913 words)

  
 Melting Point Study Questions - Answers
If the melting point is substantially lowered and has a wide melting point range, the compound is not ibuprofen.
The melting point of such a compound needs to be taken in a sealed capillary tube.
To obtain an accurate melting point value, the device must be heated slowly near the melting point in order for the thermometer's sensor to be the same temperature as the heating block.
orgchem.colorado.edu /hndbksupport/meltingpt/mpsqans.html   (1022 words)

  
 Jewelry Sector - Melting Point and Weights of Various Metals and Alloys
The specific gravity of a metal or alloy is merely the weight in grams of one cubic centimeter.
When it is more convenient to work in troy weights, the number of ounces per cubic inch of any metal or alloy may be found by multiplying its specific gravity by the constant 0.52686.
Melting Point and Weights of Various Metals and Alloys
www.kitco.com /jewelry/meltingpoints.html   (84 words)

  
 Light Scattering for Protein Characterization   (Site not responding. Last check: )
Light scattering is ideal for studying the protein melting point phenomenon as the technique is exquisitely sensitive to large scattering objects such as aggregates and denatured protein.
The protein melting point temperature is indicative of the thermal stability of a protein.
The absence of a melting point in the treated sample seems to suggest that the treatment process was similar in effect to thermal denaturation.
www.malvern.co.uk /LabEng/industry/protein/protein_melting_point.htm   (453 words)

  
 melting point. The Columbia Encyclopedia, Sixth Edition. 2001-05
Under standard atmospheric pressure different pure crystalline solids will each melt at a different specific temperature; thus melting point is a characteristic of a substance and can be used to identify it.
When heat is applied continuously and in sufficient quantity to such solids, the temperature rises steadily until it reaches the point at which liquefaction occurs.
The quantity of heat necessary to change one gram of any substance from solid to liquid at its melting point is known as its latent heat of fusion and differs for different substances.
www.bartleby.com /65/me/meltingp.html   (305 words)

  
 [No title]
Measuring the melting point: Your TA will demonstrate the proper way to use the melting point apparatus (4) Be sure the apparatus has cooled to 120°C or less before you place your capillary in it when you're taking the melting point of pure urea or pure trans-cinnamic acid.
Mixture melting points: Pure substances melt at defined temperatures, but mixtures of organic compound melt over a range that is lower than the melting point of each of the components.
Determine the melting range of a mixture (about 50:50) of your unknown and urea and of a mixture (about 50:50) of your unknown and trans-cinnamic acid.
web.missouri.edu /~glaserr/2050f05/E1_Melting_point.doc   (512 words)

  
 Melting point -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: )
When considered as the temperature of the reverse change, it is referred to as the freezing point.
Unlike the (Being highly angry or excited; ready to boil over) boiling point, the melting point is relatively insensitive to (The force applied to a unit area of surface; measured in pascals (SI unit) or in dynes (cgs unit)) pressure.
The material with the highest known melting point at atmospheric pressure is (Used as a lubricant and as a moderator in nuclear reactors) graphite, with a melting point of 3948 kelvins.
www.absoluteastronomy.com /encyclopedia/M/Me/Melting_point.htm   (134 words)

  
 melting point --  Encyclopædia Britannica
As with the melting point, increased pressure usually raises the freezing point.
The freezing point is lower than the melting point in the case of mixtures and for certain organic compounds such as fats.
At these points of contact with inflowing warm water, the ice melts faster than it does at central lake locations, where most melting is caused by the transfer of heat from the atmosphere.
www.britannica.com /eb/article-9051921?tocId=9051921   (918 words)

  
 Melting Point
The different phases of a melt on a single sample or the melting point of three samples can thus be readily recorded.
The Electrothermal IA9400 Low Temperature Digital Melting Point Apparatus is designed specifically to enable melting tests to be carried out at temperatures as low as 0"C. The testing of waxes, fats, greases etc is often difficult because the temperature at which they change from solid to liquid is close to ambient temperature.
Four melting phases may be recorded and a batch number for the test with date, time and melt conditions permanently stored for recall or printout.
www.jepbol.com /sect3/meltel.html   (594 words)

  
 Explanation of the anomalous properties of water (1-10)
The melting point of water is over 100 K higher than expected by extrapolation of the melting points of other
Melting will only occur when there is sufficient entropy change to provide the energy required for the bond breaking.
Melting ice, within a filled and sealed fixed volume, may result in an apparently superheated state where the metastable iso-dense liquid water is stretched, relative to its equilibrium state at the (effectively) negative pressure, due to its cohesiveness.
www.sbu.ac.uk /water/explan.html   (2547 words)

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