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The name of the author is Garland. Delaware is our birth place. One of my preferred hobbies is tenting and now I'm attempting to make cash with it. After being out of my occupation for many years I became a manufacturing and distribution officer but I strategy on changing it.<br><br>My webpage ... auto warranty ([http://itcomplianceexperts.com/UserProfile/tabid/165/userId/36272/Default.aspx Continue Reading])
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{{Thermodynamics|cTopic='''[[Material properties (thermodynamics)|Material properties]]'''}}
'''[[Thermodynamics|Thermodynamic]] databases''' contain information about [[List of thermodynamic properties|thermodynamic properties]] for substances, the most important being [[enthalpy]], [[entropy]], and [[Gibbs free energy]]. Numerical values of these thermodynamic properties are collected as tables or are calculated from thermodynamic datafiles. Data is expressed as temperature-dependent values for one mole of substance at the [[Standard conditions for temperature and pressure|standard pressure]] of 101.325 kPa (1 atm), or 100 kPa (1 bar).  Unfortunately, both of these definitions for the [[Atmospheric pressure|standard condition for pressure]] are in use.
 
== Thermodynamic data ==
 
'''Thermodynamic data''' is usually presented as a table or chart of function values for one mole of a substance (or in the case of the [[steam]] tables, one kg). A '''thermodynamic datafile''' is a set of equation parameters from which the numerical data values can be calculated. Tables and datafiles are usually presented at a standard pressure of 1 bar or 1 atm, but in the case of steam and other industrially important gases, pressure may be included as a variable. Function values depend on the [[Phase (matter)|state of aggregation]] of the substance, which must be defined for the value to have any meaning. The state of aggregation for thermodynamic purposes is the ''[[Standard conditions for temperature and pressure|standard state]]'', sometimes called the ''reference state'', and defined by specifying certain conditions. The ''normal'' standard state is commonly defined as the most stable physical form of the substance at the specified [[temperature]] and a pressure of 1 bar or 1 atm.  However, since any non-normal condition could be chosen as a standard state, it must be defined in the context of use. A ''physical'' standard state is one that exists for a time sufficient to allow measurements of its properties. The most common physical standard state is one that is stable thermodynamically (i.e., the normal one). It has no tendency to transform into any other physical state.  If a substance can exist but is not thermodynamically stable (for example, a supercooled liquid), it is called a ''[[Phase (matter)|metastable]]'' state.  A ''non''-''physical'' standard state is one whose properties are obtained by extrapolation from a physical state (for example, a solid superheated above the normal melting point, or an ideal gas at a condition where the real gas is non-ideal). Metastable liquids and solids are important because some substances can persist and be used in that state indefinitely. Thermodynamic functions that refer to conditions in the normal standard state are designated with a small superscript °. The relationship between certain physical and thermodynamic properties may be described by an [[equation of state]].
 
===Enthalpy, heat content and heat capacity===
 
It is very difficult to measure the absolute amount of any thermodynamic quantity involving the [[internal energy]] (e.g. [[enthalpy]]), since the internal energy of a substance can take many forms, each of which has its own typical temperature at which it begins to become important in thermodynamic reactions. It is therefore the ''change'' in these functions that is of most interest. The isobaric change in enthalpy ''H'' above the common reference temperature of 298.15 K (25 °C) is called the ''high temperature heat content'', the ''[[sensible heat]]'', or the ''relative high-temperature enthalpy'', and called henceforth the '''heat content'''. Different databases designate this term in different ways; for example ''H''<sub>T</sub>-''H''<sub>298</sub>, ''H''°-''H''°<sub>298</sub>, ''H''°<sub>T</sub>-''H''°<sub>298</sub> or ''H''°-''H''°(T<sub>r</sub>), where T<sub>r</sub> means the reference temperature (usually 298.15 K, but abbreviated in heat content symbols as 298). All of these terms mean the molar heat content for a substance in its normal standard state above a reference temperature of 298.15 K. Data for gases is for the hypothetical [[ideal gas]] at the designated standard pressure. The [[SI system|SI]] unit for enthalpy is J/mol, and is a positive number above the reference temperature.  The heat content has been measured and tabulated for virtually all known substances, and is commonly expressed as a [[polynomial]] function of temperature. The heat content of an ideal gas is independent of pressure (or volume), but the heat content of real gases varies with pressure, hence the need to define the state for the gas (real or ideal) and the pressure. Note that for some thermodynamic databases such as for steam, the reference temperature is 273.15 K (0 °C).
 
The ''[[heat capacity]]'' C is the ratio of heat added to the temperature increase. For an incremental isobaric addition of heat:
 
<div align="center"><math>C_P(T)=\left \{ \lim_{\Delta T \to 0}\frac{\Delta H}{\Delta T}\right \}=\left ( \frac{\partial H}{\partial T}\right ) _p</math></div>
 
''C<sub>p</sub>'' is therefore the slope of a plot of temperature vs. isobaric heat content (or the derivative of a temperature/heat content equation).  The SI units for heat capacity are J/(mol·K).
 
[[Image:Heat Content of Selected Substances.PNG|frame|center|'''Molar heat content''' of four substances in their designated states above 298.15 K and at 1 atm pressure. CaO(c) and Rh(c) are in their normal standard state of crystalline solid at all temperatures. S<sub>2</sub>(g) is a non-physical state below about 882 K and NiO(g) is a non-physical state at all temperatures.]]
 
[[Image:Heat Capacity of Selected Substances.PNG|frame|center|'''Molar heat capacity''' of four substances in their designated states at 1 atm pressure. CaO(c) and Rh(c) are in their normal standard state of crystalline solid at all temperatures. S<sub>2</sub>(g) is a non-physical state below about 882 K and NiO(g) is a non-physical state at all temperatures.]]
 
===Enthalpy change of phase transitions===
 
When heat is added to a [[Phase (matter)|condensed-phase]] substance, its temperature increases until a phase change temperature is reached. With further addition of heat, the temperature remains constant while the [[phase transition]] takes place. The amount of substance that transforms is a function of the amount of heat added. After the transition is complete, adding more heat increases the temperature. In other words, the enthalpy of a substance changes '''isothermally''' as it undergoes a physical change. The enthalpy change resulting from a phase transition is designated Δ''H''. There are four types of enthalpy changes resulting from a phase transition. To wit:
:* ''Enthalpy of transformation''.  This applies to the transformations from one solid phase to another, such as the transformation from α-Fe (bcc ferrite) to <math>\gamma</math>-Fe (fcc austenite). The transformation is designated Δ''H''<sub>tr</sub>.
:* ''Enthalpy of fusion or [[melting]]''. This applies to the transition of a solid to a liquid and is designated Δ''H''<sub>m</sub>.
:* ''Enthalpy of [[vaporization]]''. This applies to the transition of a liquid to a vapor and is designated Δ''H''<sub>v</sub>.
:* ''Enthalpy of [[Sublimation (chemistry)|sublimation]]''. This applies to the transition of a solid to a vapor and is designated Δ''H''<sub>s</sub>. 
''C<sub>p</sub>'' is infinite at phase transition temperatures because the enthalpy changes isothermally. At the [[Curie temperature]], ''C<sub>p</sub>'' shows a sharp discontinuity while the enthalpy has a change in slope.
 
Values of Δ''H'' are usually given for the transition at the normal standard state temperature for the two states, and if so, are designated with a superscript °. Δ''H'' for a phase transition is a weak function of temperature. In some texts, the heats of phase transitions are called [[Latent heat|''latent'' heats]] (for example, ''latent heat of fusion'').
 
[[Image:Heat Content of Zn(c,l,g).PNG|frame|center|'''Molar enthalpy of zinc''' above 298.15 K and at 1 atm pressure, showing discontinuities at the melting and boiling points. The Δ''H''°m of zinc is 7323 J/mol, and the Δ''H''°v is 115 330 J/mol.]]
 
===Enthalpy change for a chemical reaction===
An enthalpy change occurs during a [[chemical reaction]]. For the special case of the formation of a compound from the [[Chemical element|elements]], the change is designated Δ''H''<sub>form</sub> and is a weak function of temperature. Values of Δ''H''<sub>form</sub> are usually given where the elements and compound are in their normal standard states, and as such are designated ''standard heats'' of formation, as designated by a superscript °.  The Δ''H''°<sub>form</sub> undergoes discontinuities at a phase transition temperatures of the constituent element(s) and the compound. The enthalpy change for any standard reaction is designated Δ''H''°<sub>rx</sub>.
 
[[Image:Standard Heat of Formation of ZnBr2(c,l).PNG|frame|center|'''Standard molar heat of formation''' of ZnBr<sub>2</sub>(c,l) from the elements, showing discontinuities at transition temperatures of the elements and the compound.]]
 
===Entropy and Gibbs energy===
 
The [[entropy]] of a system is another thermodynamic quantity that is not easily measured. However, using a combination of theoretical and experimental techniques, entropy can in fact be accurately estimated.  At low temperatures, the [[Debye model]] leads to the result that the atomic heat capacity ''C''<sub>v</sub> for solids should be proportional to ''T''<sup>3</sup>, and that for perfect crystalline solids it should become zero at [[absolute zero]]. Experimentally, the heat capacity is measured at temperature intervals to as low a temperature as possible. Values of ''C''<sub>p</sub>/T are plotted against T for the whole range of temperatures where the substance exists in the same physical state.  The data are extrapolated from the lowest experimental temperature to 0 K using the Debye model. The [[third law of thermodynamics]] states that the entropy of a perfect crystalline substance becomes zero at 0 K.  When ''S''<sub>0</sub> is zero, the area under the curve from 0 K to any temperature gives the entropy at that temperature.  Even though the Debye model contains ''C''<sub>v</sub> instead of ''C''<sub>p</sub>, the difference between the two at temperatures near 0 K is so small as to be negligible.
 
The absolute value of entropy for a substance in its standard state at the reference temperature of 298.15 K is designated ''S''°<sub>298</sub>. Entropy increases with temperature, and is discontinuous at phase transition temperatures. The change in entropy (Δ''S''°) at the normal phase transition temperature is equal to the heat of transition divided by the transition temperature. The SI units for entropy are J/(mol·K).
 
[[Image:Absolute Entropy of Strontium.PNG|frame|center|'''Absolute entropy of strontium'''. The solid line refers to the entropy of strontium in its normal standard state at 1 atm pressure. The dashed line refers to the entropy of strontium vapor in a non-physical state.]]
 
The standard entropy change for the formation of a compound from the elements, or for any standard reaction is designated Δ''S''°<sub>form</sub> or Δ''S''°<sub>rx</sub>. The entropy change is obtained by summing the absolute entropies of the products minus the sum of the absolute entropies of the reactants.
Like enthalpy, the Gibbs energy ''G'' has no intrinsic value, so it is the change in ''G'' that is of interest.
Furthermore, there is no change in ''G'' at phase transitions between substances in their standard states.
Hence, the main functional application of Gibbs energy from a thermodynamic database is its change in value during the formation of a compound from the standard-state elements, or for any standard chemical reaction (Δ''G''°<sub>form</sub> or Δ''G''°<sub>rx</sub>).
The SI units of Gibbs energy are the same as for enthalpy (J/mol).
 
[[Image:Heat and Gibbs Energy of Pb Chlorination.PNG|frame|center|'''Standard heat and Gibbs energy change''' for the reaction: <div align="center"><math>Pb(c,l) + 2HCl(g) \Rightarrow PbCl_2 + H_2(g)</math></div>The Δ''H''°<sub>rx</sub> shows discontinuities at the melting points of Pb (600.65 K) and PbCl<sub>2</sub> (771 K). Δ''G''°<sub>rx</sub> is not discontinuous at these phase transition temperatures, but does undergo a change in slope, which is almost imperceptible on the chart.]]
 
===Additional functions===
Compilers of thermochemical databases may contain some additional thermodynamic functions. For example, the absolute enthalpy of a substance ''H''(''T'') is defined in terms of its formation enthalpy and its heat content as follows:
 
<div align="center"><math> H(T) = \Delta H^\circ_{form,298} + [H_T - H_{298}] </math></div>
 
For an element, ''H''(''T'') and [''H''<sub>T</sub> - ''H''<sub>298</sub>] are identical at all temperatures because Δ''H''°<sub>form</sub> is zero, and of course at 298.15 K, ''H''(''T'') = 0.  For a compound:
 
<div align="center"><math> \Delta H^\circ_{form} = H(T)compound - \sum \left \{ H(T)elements \right \} </math></div>
 
Similarly, the absolute Gibbs energy ''G''(''T'') is defined by the absolute enthalpy and entropy of a substance:
 
<div align="center"><math> G(T) = H(T) - T \times S(T) </math></div>
 
For a compound:
 
<div align="center"><math> \Delta G^\circ_{form} = G(T)compound - \sum \left \{ G(T)elements \right \} </math></div>
 
Some tables may also contain the Gibbs energy function (''H''°<sub>298.15</sub> – ''G''°<sub>T</sub>)/''T'' which is defined in terms of the entropy and heat content.
 
<div align="center"><math> (H^\circ_{298} - G^\circ_T) / T = S^\circ_T - (H_T - H_{298}) / T </math></div>
 
The Gibbs energy function has the same units as entropy, but unlike entropy, exhibits no discontinuity at normal phase transition temperatures. 
 
The log<sub>10</sub> of the [[equilibrium constant]] ''K''<sub>eq</sub> is often listed, which is calculated from the defining thermodynamic equation.
 
<div align="center"><math> \log_{10} \left ( K_{eq} \right ) = -\Delta G^\circ_{form} /(19.1448T) </math></div>
 
==Thermodynamic databases==
 
A '''thermodynamic database''' consists of sets of critically evaluated values for the major thermodynamic functions.
Originally, data was presented as printed tables at 1 atm and at certain temperatures, usually 100° intervals and at phase transition temperatures. Some compilations included polynomial equations that could be used to reproduce the tabular values. More recently, computerized databases are used which consist of the equation parameters and subroutines to calculate specific values at any temperature and prepare tables for printing. Computerized databases often include subroutines for calculating reaction properties and displaying the data as charts.
 
Thermodynamic data comes from many types of experiments, such as [[calorimetry]], [[Phase equilibrium|phase equilibria]], [[spectroscopy]], composition measurements of [[chemical equilibrium]] mixtures, and [[Electromotive force|emf]] measurements of reversible reactions. A proper database takes all available information about the elements and compounds in the database, and assures that the presented results are ''internally consistent''. Internal consistency requires that all values of the thermodynamic functions are correctly calculated by application of the appropriate thermodynamic equations. For example, values of the Gibbs energy obtained from high-temperature equilibrium emf methods must be identical to those calculated from calorimetric measurements of the enthalpy and entropy values. The database provider must use recognized data analysis procedures to resolve differences between data obtained by different types of experiments.
 
All thermodynamic data is a non-linear function of temperature (and pressure), but there is no universal equation format for expressing the various functions. Here we describe a commonly used polynomial equation to express the temperature dependence of the heat content. A common six-term equation for the isobaric heat content is:
 
<div align="center"><math> H_T - H_{298} = A(T) + B(T^2) + C(T^{-1}) + D(T^{0.5}) + E(T^3) + F \, </math></div>
 
Regardless of the equation format, the heat of formation of a compound at any temperature is Δ''H''°<sub>form</sub> at 298.15 K, plus the sum of the heat content parameters of the products minus the sum of the heat content parameters of the reactants. The ''C''<sub>p</sub> equation is obtained by taking the derivative of the heat content equation.
 
<div align="center"><math> C_P = A + 2B(T) - C(T^{-2}) + \textstyle \frac {1}{2} D(T^{-0.5}) + 3E(T^2) \,</math></div>
 
The entropy equation is obtained by integrating the ''C''<sub>p</sub>/T equation:
 
<div align="center"><math> S^\circ_T = A(\ln T) + 2B(T) + \textstyle \frac {1}{2}C(T^{-2}) - D(T^{\textstyle - \frac {1}{2}}) + 1 \textstyle \frac {1}{2} E(T^2) + F'</math></div>
 
F' is a constant of integration obtained by inserting ''S''° at any temperature ''T''. The Gibbs energy of formation of a compound is obtained from the defining equation Δ''G''°<sub>form</sub> = Δ''H''°<sub>form</sub> – T(Δ''S''°<sub>form</sub>), and is expressed as
 
<div align="center"><math> \Delta G^\circ_{form} = ( \Delta A - \Delta F' )T - \Delta A ( T \ln T ) - \Delta B ( T^2 ) + \textstyle \frac {1}{2} \Delta C ( T^{-1} ) + 2 \Delta D ( T^{ \textstyle \frac {1}{2} } ) </math></div>
 
<div align="center"><math> - \textstyle \frac {1}{2} \Delta E (T^3) + \Delta F + \Delta H^\circ_{form 298} </math></div>
 
For most substances, Δ''G''°<sub>form</sub> deviates only slightly from linearity with temperature, so over a short temperature span, the seven-term equation can be replaced by a three-term equation, whose parameter values are obtained by regression of tabular values. 
 
<div align="center"><math> \Delta G^\circ_{form} = \alpha T + \beta (T \ln T) + \chi </math></div>
 
Depending on the accuracy of the data and the length of the temperature span, the heat content equation may require more or fewer terms. Over a very long temperature span, two equations may be used instead of one.  It is unwise to extrapolate the equations to obtain values outside the range of experimental data used to derive the equation parameters.
 
===Thermodynamic datafiles===
 
The equation parameters and all other information required to calculate values of the important thermodynamic functions are stored in a thermodynamic datafile. The values are organized in a format that makes them readable by a thermodynamic calculation program or for use in a spreadsheet. For example, the [[Microsoft Excel|Excel]]-based thermodynamic database FREED [http://www.thermart.net] creates the following type of datafile, here for a standard pressure of 1 atm.
 
[[Image:Thermodynamic Datafile for MbCl2(c,l,g).PNG|frame|center|'''Thermodynamic datafile''' for MgCl<sub>2</sub>(c,l,g) from FREED. Some values have truncated significant figures for display purposes. The explanation for the values is shown below.]]
 
:* Row 1. Molar mass of species, density at 298.15 K, Δ''H''°<sub>form 298.15</sub>, ''S''°<sub>298.15</sub>. and the upper temperature limit for the file.
:* Row 2. Number of ''C''<sub>p</sub> equations required.  Here, three because of three species phases.
:* Row 3. Values of the five parameters for the first ''C''<sub>p</sub> equation; temperature limit for the equation.
:* Row 4. Values of the five parameters for the second ''C''<sub>p</sub> equation; temperature limit for the equation.
:* Row 5. Values of the five parameters for the third ''C''<sub>p</sub> equation; temperature limit for the equation.
:* Row 6. Number of ''H''<sub>T</sub> - ''H''<sub>298</sub> equations required.
:* Row 7. Values of the six parameters for the first ''H''<sub>T</sub> - ''H''<sub>298</sub> equation; temperature limit for the equation, and Δ''H''°<sub>trans</sub> for the first phase change.
:* Row 8. Values of the six parameters for the second ''H''<sub>T</sub> - ''H''<sub>298</sub> equation; temperature limit for the equation, and Δ''H''°<sub>trans</sub> for the second phase change.
:* Row 9. Values of the six parameters for the third ''H''<sub>T</sub> - ''H''<sub>298</sub> equation; temperature limit for the equation, and Δ''H''°<sub>trans</sub> for the third phase change.
:* Row 10. Number of Δ''H''°<sub>form</sub> equations required.  Here five; three for species phases and two because one of the elements has a phase change.
:* Row 11. Values of the six parameters for the first Δ''H''°<sub>form</sub> equation; temperature limit for the equation.
:* Row 12. Values of the six parameters for the second Δ''H''°<sub>form</sub> equation; temperature limit for the equation.
:* Row 13. Values of the six parameters for the third Δ''H''°<sub>form</sub> equation; temperature limit for the equation.
:* Row 14. Values of the six parameters for the fourth Δ''H''°<sub>form</sub> equation; temperature limit for the equation.
:* Row 15. Values of the six parameters for the fifth Δ''H''°<sub>form</sub> equation; temperature limit for the equation.
:* Row 16. Number of Δ''G''°<sub>form</sub> equations required.
:* Row 17. Values of the seven parameters for the first Δ''G''°<sub>form</sub> equation; temperature limit for the equation.
:* Row 18. Values of the seven parameters for the second Δ''G''°<sub>form</sub> equation; temperature limit for the equation.
:* Row 19. Values of the seven parameters for the third Δ''G''°<sub>form</sub> equation; temperature limit for the equation.
:* Row 20. Values of the seven parameters for the fourth Δ''G''°<sub>form</sub> equation; temperature limit for the equation.
:* Row 21. Values of the seven parameters for the fifth Δ''G''°<sub>form</sub> equation; temperature limit for the equation.
 
Most computerized databases will create a table of thermodynamic values using the values from the datafile.  For MgCl<sub>2</sub>(c,l,g) at 1 atm pressure: 
 
[[Image:Thermodynamic Properties Table for MgCl2(c,l,g).PNG|frame|center|'''Thermodynamic properties table''' for MgCl<sub>2</sub>(c,l,g), from the FREED datafile. Some values have truncated significant figures for display purposes.]]
 
The table format is a common way to display thermodynamic data.  The FREED table gives additional information in the top rows, such as the mass and amount composition and transition temperatures of the constituent elements.  Transition temperatures for the constituent elements have dashes ------- in the first column in a blank row, such as at 922 K, the melting point of Mg. Transition temperatures for the substance have two blank rows with dashes, and a center row with the defined transition and the enthalpy change, such as the melting point of MgCl<sub>2</sub> at 980 K. The datafile equations are at the bottom of the table, and the entire table is in an Excel worksheet. This is particularly useful when the data is intended for making specific calculations.
 
==See also==
 
* [[Chemical thermodynamics]]
* [[Physical chemistry]]
* [[Materials science]]
* [[Laws of thermodynamics]]
* [[Thermochemistry]]
* [[Standard temperature and pressure]]
* [[Dortmund Data Bank]]
* [[CALPHAD (method)]]
 
==References==
 
*{{cite book|last = Barin|first=Ihsan|year=2004
| title=Thermochemical Data of Pure Substances|publisher=Wiley-VCH
| isbn=3-527-30993-4}}
*{{cite book| last = Chase| first = M. W.
| year = 1998| title = NIST - JANAF Thermochemical Tables
| edition = Fourth| publisher = Journal of Physical and Chemical Reference Data
| isbn =1-56396-831-2| url = http://www.aip.org/pubs/books/jpcrd_books.html}}
*{{cite book| last = Cox| first=J. D.
| coauthors=Wagman, D.D. and V. A. Medvedev, V. A.|year= 1989
| title=CODATA Key Values for Thermodynamics|publisher=John Benjamins Publishing Co
| isbn=0-89116-758-7}}
*{{cite book| last = Hummel|first=Wolfgang
|coauthors=Urs Berner, Enzo Curti, F. J. Pearson, and Tres Thoenen|year=2002
|title=Nagra/Psi Chemical Thermodynamic Data Base|publisher=Universal Publishers
|isbn=1-58112-620-4}}
*{{cite book|last=Lide|first=David R.|coauthors=Henry V. Kehiaian|year=1994
|title=CRC Handbook of Thermophysical and Thermochemical Data|edition=book & disk
|isbn=0-8493-0197-1|publisher=CRC Press|location=Boca Raton}}
*{{cite journal|last=Pankratz|first=L. B.|year=1982
|title=Thermodynamic Properties of Elements and Oxides
|journal=U. S. Bureau of Mines Bulletin|volume=672}}
*{{cite journal|last=Pankratz|first=L. B.|year=1984
|title=Thermodynamic Properties of Halides
|journal=U. S. Bureau of Mines Bulletin|volume=674}}
*{{cite journal|last=Pankratz|first=L. B.|coauthors=A. D. Mah and S. W. Watson|year=1987
|title=Thermodynamic Properties of Sulfides
|journal=U. S. Bureau of Mines Bulletin|volume=689}}
*{{cite journal|last=Pankratz|first=L. B.|year=1994
|title=Thermodynamic Properties of Carbides, Nitrides, and Other Selected Substances
|journal=U. S. Bureau of Mines Bulletin|volume=696}} 
*Robie, Richard A., and Bruce S. Hemingway (1995).  ''Thermodynamic Properties of Minerals . . . at Higher Temperatures'', U. S. Geological Survey Bulletin 2131. 
*Yaws, Carl L. (2007).  [http://www.gulfpub.com/product.asp?PositionID=search&ProductID=6361 ''Yaws Handbook of Thermodynamic Properties for Hydrocarbons & Chemicals''], Gulf Publishing Company.  ISBN 1-933762-07-1.
*Gurvich, L.V., Veitz, I.V., et al. (1989) Thermodynamic Properties of Individual Substances. Fourth edition, Hemisphere Pub Co. NY, L., Vol.1 in 2 parts.
 
==External links==
* [http://webbook.nist.gov/ NIST WebBook] A gateway to the data collection of the National Institute of Standards and Technology.
* [http://www.grc.nasa.gov/WWW/CEAWeb/ceaThermoBuild.htm NASA Glenn ThermoBuild] A web interface to generate tabulated thermodynamic data.
* [ftp://ftp.technion.ac.il/pub/supported/aetdd/thermodynamics/ Burcat's Thermodynamic Database] Database for more than 2,500 chemical species.
* [http://www.thermodata.org THERMODATA] Thermochemical Databases and Software.
* [http://www.aiche.org/TechnicalSocieties/DIPPR/index.aspx DIPPR] The Design Institute for Physical Properties
* [http://dippr.byu.edu DIPPR 801] Critically evaluated thermophysical property database useful for chemical process design and equilibrium calculations.
* [http://www.mtdata-software.com MTDATA software and databases for calculation of thermodynamic properties and phase equilibria]
* [http://www.steamtablesonline.com Free Steam Tables Online] calculator based on IAPWS-IF97
* [http://www.crct.polymtl.ca/factweb.php.  FACT-Web programs]  Various on-line tools for obtaining thermodynamic data and making equilibrium calculations. 
 
[[Category:Thermodynamics]]
[[Category:Scientific databases]]

Latest revision as of 23:40, 27 March 2013

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my web-site; cheap psychic readings [netwk.hannam.ac.kr] Thermodynamic databases contain information about thermodynamic properties for substances, the most important being enthalpy, entropy, and Gibbs free energy. Numerical values of these thermodynamic properties are collected as tables or are calculated from thermodynamic datafiles. Data is expressed as temperature-dependent values for one mole of substance at the standard pressure of 101.325 kPa (1 atm), or 100 kPa (1 bar). Unfortunately, both of these definitions for the standard condition for pressure are in use.

Thermodynamic data

Thermodynamic data is usually presented as a table or chart of function values for one mole of a substance (or in the case of the steam tables, one kg). A thermodynamic datafile is a set of equation parameters from which the numerical data values can be calculated. Tables and datafiles are usually presented at a standard pressure of 1 bar or 1 atm, but in the case of steam and other industrially important gases, pressure may be included as a variable. Function values depend on the state of aggregation of the substance, which must be defined for the value to have any meaning. The state of aggregation for thermodynamic purposes is the standard state, sometimes called the reference state, and defined by specifying certain conditions. The normal standard state is commonly defined as the most stable physical form of the substance at the specified temperature and a pressure of 1 bar or 1 atm. However, since any non-normal condition could be chosen as a standard state, it must be defined in the context of use. A physical standard state is one that exists for a time sufficient to allow measurements of its properties. The most common physical standard state is one that is stable thermodynamically (i.e., the normal one). It has no tendency to transform into any other physical state. If a substance can exist but is not thermodynamically stable (for example, a supercooled liquid), it is called a metastable state. A non-physical standard state is one whose properties are obtained by extrapolation from a physical state (for example, a solid superheated above the normal melting point, or an ideal gas at a condition where the real gas is non-ideal). Metastable liquids and solids are important because some substances can persist and be used in that state indefinitely. Thermodynamic functions that refer to conditions in the normal standard state are designated with a small superscript °. The relationship between certain physical and thermodynamic properties may be described by an equation of state.

Enthalpy, heat content and heat capacity

It is very difficult to measure the absolute amount of any thermodynamic quantity involving the internal energy (e.g. enthalpy), since the internal energy of a substance can take many forms, each of which has its own typical temperature at which it begins to become important in thermodynamic reactions. It is therefore the change in these functions that is of most interest. The isobaric change in enthalpy H above the common reference temperature of 298.15 K (25 °C) is called the high temperature heat content, the sensible heat, or the relative high-temperature enthalpy, and called henceforth the heat content. Different databases designate this term in different ways; for example HT-H298, H°-H°298, H°T-H°298 or H°-H°(Tr), where Tr means the reference temperature (usually 298.15 K, but abbreviated in heat content symbols as 298). All of these terms mean the molar heat content for a substance in its normal standard state above a reference temperature of 298.15 K. Data for gases is for the hypothetical ideal gas at the designated standard pressure. The SI unit for enthalpy is J/mol, and is a positive number above the reference temperature. The heat content has been measured and tabulated for virtually all known substances, and is commonly expressed as a polynomial function of temperature. The heat content of an ideal gas is independent of pressure (or volume), but the heat content of real gases varies with pressure, hence the need to define the state for the gas (real or ideal) and the pressure. Note that for some thermodynamic databases such as for steam, the reference temperature is 273.15 K (0 °C).

The heat capacity C is the ratio of heat added to the temperature increase. For an incremental isobaric addition of heat:

CP(T)={limΔT0ΔHΔT}=(HT)p

Cp is therefore the slope of a plot of temperature vs. isobaric heat content (or the derivative of a temperature/heat content equation). The SI units for heat capacity are J/(mol·K).

File:Heat Content of Selected Substances.PNG
Molar heat content of four substances in their designated states above 298.15 K and at 1 atm pressure. CaO(c) and Rh(c) are in their normal standard state of crystalline solid at all temperatures. S2(g) is a non-physical state below about 882 K and NiO(g) is a non-physical state at all temperatures.
File:Heat Capacity of Selected Substances.PNG
Molar heat capacity of four substances in their designated states at 1 atm pressure. CaO(c) and Rh(c) are in their normal standard state of crystalline solid at all temperatures. S2(g) is a non-physical state below about 882 K and NiO(g) is a non-physical state at all temperatures.

Enthalpy change of phase transitions

When heat is added to a condensed-phase substance, its temperature increases until a phase change temperature is reached. With further addition of heat, the temperature remains constant while the phase transition takes place. The amount of substance that transforms is a function of the amount of heat added. After the transition is complete, adding more heat increases the temperature. In other words, the enthalpy of a substance changes isothermally as it undergoes a physical change. The enthalpy change resulting from a phase transition is designated ΔH. There are four types of enthalpy changes resulting from a phase transition. To wit:

  • Enthalpy of transformation. This applies to the transformations from one solid phase to another, such as the transformation from α-Fe (bcc ferrite) to γ-Fe (fcc austenite). The transformation is designated ΔHtr.
  • Enthalpy of fusion or melting. This applies to the transition of a solid to a liquid and is designated ΔHm.
  • Enthalpy of vaporization. This applies to the transition of a liquid to a vapor and is designated ΔHv.
  • Enthalpy of sublimation. This applies to the transition of a solid to a vapor and is designated ΔHs.

Cp is infinite at phase transition temperatures because the enthalpy changes isothermally. At the Curie temperature, Cp shows a sharp discontinuity while the enthalpy has a change in slope.

Values of ΔH are usually given for the transition at the normal standard state temperature for the two states, and if so, are designated with a superscript °. ΔH for a phase transition is a weak function of temperature. In some texts, the heats of phase transitions are called latent heats (for example, latent heat of fusion).

File:Heat Content of Zn(c,l,g).PNG
Molar enthalpy of zinc above 298.15 K and at 1 atm pressure, showing discontinuities at the melting and boiling points. The ΔH°m of zinc is 7323 J/mol, and the ΔH°v is 115 330 J/mol.

Enthalpy change for a chemical reaction

An enthalpy change occurs during a chemical reaction. For the special case of the formation of a compound from the elements, the change is designated ΔHform and is a weak function of temperature. Values of ΔHform are usually given where the elements and compound are in their normal standard states, and as such are designated standard heats of formation, as designated by a superscript °. The ΔH°form undergoes discontinuities at a phase transition temperatures of the constituent element(s) and the compound. The enthalpy change for any standard reaction is designated ΔH°rx.

File:Standard Heat of Formation of ZnBr2(c,l).PNG
Standard molar heat of formation of ZnBr2(c,l) from the elements, showing discontinuities at transition temperatures of the elements and the compound.

Entropy and Gibbs energy

The entropy of a system is another thermodynamic quantity that is not easily measured. However, using a combination of theoretical and experimental techniques, entropy can in fact be accurately estimated. At low temperatures, the Debye model leads to the result that the atomic heat capacity Cv for solids should be proportional to T3, and that for perfect crystalline solids it should become zero at absolute zero. Experimentally, the heat capacity is measured at temperature intervals to as low a temperature as possible. Values of Cp/T are plotted against T for the whole range of temperatures where the substance exists in the same physical state. The data are extrapolated from the lowest experimental temperature to 0 K using the Debye model. The third law of thermodynamics states that the entropy of a perfect crystalline substance becomes zero at 0 K. When S0 is zero, the area under the curve from 0 K to any temperature gives the entropy at that temperature. Even though the Debye model contains Cv instead of Cp, the difference between the two at temperatures near 0 K is so small as to be negligible.

The absolute value of entropy for a substance in its standard state at the reference temperature of 298.15 K is designated S°298. Entropy increases with temperature, and is discontinuous at phase transition temperatures. The change in entropy (ΔS°) at the normal phase transition temperature is equal to the heat of transition divided by the transition temperature. The SI units for entropy are J/(mol·K).

Absolute entropy of strontium. The solid line refers to the entropy of strontium in its normal standard state at 1 atm pressure. The dashed line refers to the entropy of strontium vapor in a non-physical state.

The standard entropy change for the formation of a compound from the elements, or for any standard reaction is designated ΔS°form or ΔS°rx. The entropy change is obtained by summing the absolute entropies of the products minus the sum of the absolute entropies of the reactants. Like enthalpy, the Gibbs energy G has no intrinsic value, so it is the change in G that is of interest. Furthermore, there is no change in G at phase transitions between substances in their standard states. Hence, the main functional application of Gibbs energy from a thermodynamic database is its change in value during the formation of a compound from the standard-state elements, or for any standard chemical reaction (ΔG°form or ΔG°rx). The SI units of Gibbs energy are the same as for enthalpy (J/mol).

File:Heat and Gibbs Energy of Pb Chlorination.PNG
Standard heat and Gibbs energy change for the reaction: The ΔH°rx shows discontinuities at the melting points of Pb (600.65 K) and PbCl2 (771 K). ΔG°rx is not discontinuous at these phase transition temperatures, but does undergo a change in slope, which is almost imperceptible on the chart.

Additional functions

Compilers of thermochemical databases may contain some additional thermodynamic functions. For example, the absolute enthalpy of a substance H(T) is defined in terms of its formation enthalpy and its heat content as follows:

H(T)=ΔHform,298+[HTH298]

For an element, H(T) and [HT - H298] are identical at all temperatures because ΔH°form is zero, and of course at 298.15 K, H(T) = 0. For a compound:

ΔHform=H(T)compound{H(T)elements}

Similarly, the absolute Gibbs energy G(T) is defined by the absolute enthalpy and entropy of a substance:

G(T)=H(T)T×S(T)

For a compound:

ΔGform=G(T)compound{G(T)elements}

Some tables may also contain the Gibbs energy function (H°298.15G°T)/T which is defined in terms of the entropy and heat content.

(H298GT)/T=ST(HTH298)/T

The Gibbs energy function has the same units as entropy, but unlike entropy, exhibits no discontinuity at normal phase transition temperatures.

The log10 of the equilibrium constant Keq is often listed, which is calculated from the defining thermodynamic equation.

log10(Keq)=ΔGform/(19.1448T)

Thermodynamic databases

A thermodynamic database consists of sets of critically evaluated values for the major thermodynamic functions. Originally, data was presented as printed tables at 1 atm and at certain temperatures, usually 100° intervals and at phase transition temperatures. Some compilations included polynomial equations that could be used to reproduce the tabular values. More recently, computerized databases are used which consist of the equation parameters and subroutines to calculate specific values at any temperature and prepare tables for printing. Computerized databases often include subroutines for calculating reaction properties and displaying the data as charts.

Thermodynamic data comes from many types of experiments, such as calorimetry, phase equilibria, spectroscopy, composition measurements of chemical equilibrium mixtures, and emf measurements of reversible reactions. A proper database takes all available information about the elements and compounds in the database, and assures that the presented results are internally consistent. Internal consistency requires that all values of the thermodynamic functions are correctly calculated by application of the appropriate thermodynamic equations. For example, values of the Gibbs energy obtained from high-temperature equilibrium emf methods must be identical to those calculated from calorimetric measurements of the enthalpy and entropy values. The database provider must use recognized data analysis procedures to resolve differences between data obtained by different types of experiments.

All thermodynamic data is a non-linear function of temperature (and pressure), but there is no universal equation format for expressing the various functions. Here we describe a commonly used polynomial equation to express the temperature dependence of the heat content. A common six-term equation for the isobaric heat content is:

HTH298=A(T)+B(T2)+C(T1)+D(T0.5)+E(T3)+F

Regardless of the equation format, the heat of formation of a compound at any temperature is ΔH°form at 298.15 K, plus the sum of the heat content parameters of the products minus the sum of the heat content parameters of the reactants. The Cp equation is obtained by taking the derivative of the heat content equation.

CP=A+2B(T)C(T2)+12D(T0.5)+3E(T2)

The entropy equation is obtained by integrating the Cp/T equation:

ST=A(lnT)+2B(T)+12C(T2)D(T12)+112E(T2)+F

F' is a constant of integration obtained by inserting S° at any temperature T. The Gibbs energy of formation of a compound is obtained from the defining equation ΔG°form = ΔH°form – T(ΔS°form), and is expressed as

ΔGform=(ΔAΔF)TΔA(TlnT)ΔB(T2)+12ΔC(T1)+2ΔD(T12)
12ΔE(T3)+ΔF+ΔHform298

For most substances, ΔG°form deviates only slightly from linearity with temperature, so over a short temperature span, the seven-term equation can be replaced by a three-term equation, whose parameter values are obtained by regression of tabular values.

ΔGform=αT+β(TlnT)+χ

Depending on the accuracy of the data and the length of the temperature span, the heat content equation may require more or fewer terms. Over a very long temperature span, two equations may be used instead of one. It is unwise to extrapolate the equations to obtain values outside the range of experimental data used to derive the equation parameters.

Thermodynamic datafiles

The equation parameters and all other information required to calculate values of the important thermodynamic functions are stored in a thermodynamic datafile. The values are organized in a format that makes them readable by a thermodynamic calculation program or for use in a spreadsheet. For example, the Excel-based thermodynamic database FREED [1] creates the following type of datafile, here for a standard pressure of 1 atm.

File:Thermodynamic Datafile for MbCl2(c,l,g).PNG
Thermodynamic datafile for MgCl2(c,l,g) from FREED. Some values have truncated significant figures for display purposes. The explanation for the values is shown below.
  • Row 1. Molar mass of species, density at 298.15 K, ΔH°form 298.15, S°298.15. and the upper temperature limit for the file.
  • Row 2. Number of Cp equations required. Here, three because of three species phases.
  • Row 3. Values of the five parameters for the first Cp equation; temperature limit for the equation.
  • Row 4. Values of the five parameters for the second Cp equation; temperature limit for the equation.
  • Row 5. Values of the five parameters for the third Cp equation; temperature limit for the equation.
  • Row 6. Number of HT - H298 equations required.
  • Row 7. Values of the six parameters for the first HT - H298 equation; temperature limit for the equation, and ΔH°trans for the first phase change.
  • Row 8. Values of the six parameters for the second HT - H298 equation; temperature limit for the equation, and ΔH°trans for the second phase change.
  • Row 9. Values of the six parameters for the third HT - H298 equation; temperature limit for the equation, and ΔH°trans for the third phase change.
  • Row 10. Number of ΔH°form equations required. Here five; three for species phases and two because one of the elements has a phase change.
  • Row 11. Values of the six parameters for the first ΔH°form equation; temperature limit for the equation.
  • Row 12. Values of the six parameters for the second ΔH°form equation; temperature limit for the equation.
  • Row 13. Values of the six parameters for the third ΔH°form equation; temperature limit for the equation.
  • Row 14. Values of the six parameters for the fourth ΔH°form equation; temperature limit for the equation.
  • Row 15. Values of the six parameters for the fifth ΔH°form equation; temperature limit for the equation.
  • Row 16. Number of ΔG°form equations required.
  • Row 17. Values of the seven parameters for the first ΔG°form equation; temperature limit for the equation.
  • Row 18. Values of the seven parameters for the second ΔG°form equation; temperature limit for the equation.
  • Row 19. Values of the seven parameters for the third ΔG°form equation; temperature limit for the equation.
  • Row 20. Values of the seven parameters for the fourth ΔG°form equation; temperature limit for the equation.
  • Row 21. Values of the seven parameters for the fifth ΔG°form equation; temperature limit for the equation.

Most computerized databases will create a table of thermodynamic values using the values from the datafile. For MgCl2(c,l,g) at 1 atm pressure:

File:Thermodynamic Properties Table for MgCl2(c,l,g).PNG
Thermodynamic properties table for MgCl2(c,l,g), from the FREED datafile. Some values have truncated significant figures for display purposes.

The table format is a common way to display thermodynamic data. The FREED table gives additional information in the top rows, such as the mass and amount composition and transition temperatures of the constituent elements. Transition temperatures for the constituent elements have dashes ------- in the first column in a blank row, such as at 922 K, the melting point of Mg. Transition temperatures for the substance have two blank rows with dashes, and a center row with the defined transition and the enthalpy change, such as the melting point of MgCl2 at 980 K. The datafile equations are at the bottom of the table, and the entire table is in an Excel worksheet. This is particularly useful when the data is intended for making specific calculations.

See also

References

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  • 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

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    The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

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    In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

    Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

    Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

    A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

    The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

    There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
  • One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

    In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

    Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

    Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

    A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

    The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

    There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
  • Robie, Richard A., and Bruce S. Hemingway (1995). Thermodynamic Properties of Minerals . . . at Higher Temperatures, U. S. Geological Survey Bulletin 2131.
  • Yaws, Carl L. (2007). Yaws Handbook of Thermodynamic Properties for Hydrocarbons & Chemicals, Gulf Publishing Company. ISBN 1-933762-07-1.
  • Gurvich, L.V., Veitz, I.V., et al. (1989) Thermodynamic Properties of Individual Substances. Fourth edition, Hemisphere Pub Co. NY, L., Vol.1 in 2 parts.

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