Information about Standard State
In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals exactly). This pressure was changed from 1 atm (101.325 kilopascals) by IUPAC in 1990.[1] The standard state of a material can be defined at any given temperature, most commonly 25 degrees Celsius, although quite a few texts (especially in related disciplines such as physics and engineering) use 0 degrees Celsius for Standard Temperature and Pressure (STP).
It should be noted that the standard state is an arbitrarily chosen non-zero value, not a natural zero point.
For a given material or substance, the standard state is the reference state for the material's thermodynamic state properties such as enthalpy, entropy, Gibbs free energy, and for many other material standards. The standard enthalpy of formation for an element in its standard state is 0.
When the standard state is referred to in a chemical reaction, it also includes the condition that the concentrations of all solutions are at unity (or another designated quantity) for whatever measure of concentration is specified. If that is molarity that would be 1 mol·dm-3 and for molality 1 mol·kg-1. If mole fraction is used, the pure liquid or solid is the standard state (x=1). As it is possible (and in principle legitimate) to take a different unit for each of the species in the reaction, the nature of the standard state needs to be specified when reporting or tabulating. Although a definition involving 1 mol/L (molarity at unity) of A in combination with pure B (mole fraction at unity) is clearly a condition that can never be met, such a non-existent standard state nevertheless leads to a consistent system of tabulated values, provided it is used consistently by all. Of course these values are different from those where a different standard state is adopted.
In the time of their development (the 19th century) the Plimsoll - symbol was adopted as a superscripto to indicate the non-zero nature of the chosen reference state. For typographic reasons this symbol is often abridged to a rather misleading zero superscript 0 in later texts.
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A decimetre (American spelling: decimeter, symbol dm
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It should be noted that the standard state is an arbitrarily chosen non-zero value, not a natural zero point.
For a given material or substance, the standard state is the reference state for the material's thermodynamic state properties such as enthalpy, entropy, Gibbs free energy, and for many other material standards. The standard enthalpy of formation for an element in its standard state is 0.
When the standard state is referred to in a chemical reaction, it also includes the condition that the concentrations of all solutions are at unity (or another designated quantity) for whatever measure of concentration is specified. If that is molarity that would be 1 mol·dm-3 and for molality 1 mol·kg-1. If mole fraction is used, the pure liquid or solid is the standard state (x=1). As it is possible (and in principle legitimate) to take a different unit for each of the species in the reaction, the nature of the standard state needs to be specified when reporting or tabulating. Although a definition involving 1 mol/L (molarity at unity) of A in combination with pure B (mole fraction at unity) is clearly a condition that can never be met, such a non-existent standard state nevertheless leads to a consistent system of tabulated values, provided it is used consistently by all. Of course these values are different from those where a different standard state is adopted.
In the time of their development (the 19th century) the Plimsoll - symbol was adopted as a superscript
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In physics, the term state is used in several related senses, each of which expresses something about the way a physical system is.
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- State is sometimes used as a synonym for phase of matter.
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The bar (symbol bar), decibar (symbol dbar) and the millibar (symbol mbar, also mb) are units of pressure. They are not SI units, but they are accepted for use with the SI.
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The pascal (symbol: Pa) is the SI derived unit of pressure or stress (also: Young's modulus and tensile strength). It is a measure of perpendicular force per unit area i.e. equivalent to one newton per square meter or one Joule per cubic meter.
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Standard atmosphere is a pressure defined as 101 325 Pa and used as unit of pressure (symbol: atm). Standard atmosphere is a non-SI unit that is internationally recognized.
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The International Union of Pure and Applied Chemistry (IUPAC) (IPA: [aɪ ju pæk]) is an international non-governmental organization established in 1919 devoted to the advancement of chemistry.
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Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). The degree Celsius (symbol: °C) can refer to a specific temperature on the Celsius scale
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Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). The degree Celsius (symbol: °C) can refer to a specific temperature on the Celsius scale
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In chemistry and other sciences, STP or standard temperature and pressure is a standard set of conditions for experimental measurements, to enable comparisons to be made between sets of data.
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Arbitrary is a term given to choices and actions which are considered to be done not by means of any underlying principle or logic, but by whim or some decidedly illogical formula.
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In thermodynamics and molecular chemistry, the enthalpy or heat content (denoted as H or ΔH, or rarely as χ) is a quotient or description of thermodynamic potential of a system, which can be used to calculate the "useful" work
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Ice melting - a classic example of entropy increasing[1] described in 1862 by Rudolf Clausius as an increase in the disgregation of the molecules of the body of ice.
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In thermodynamics, the Gibbs free energy (IUPAC recommended name: Gibbs energy or Gibbs function) is a thermodynamic potential which measures the "useful" or process-initiating work obtainable from an isothermal, isobaric thermodynamic system.
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The standard enthalpy of formation or "standard heat of formation" of a compound is the change of enthalpy that accompanies the formation of 1 mole of a substance in its standard state from its constituent elements in their standard states (the most stable form of the element at
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chemical reaction is a process that results in the interconversion of chemical substances.[1] The substance or substances initially involved in a chemical reaction are called reactants.
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In chemistry, concentration is the measure of how much of a given substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of
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This article is about chemical solutions. For other uses, see Solution (disambiguation).
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The mole (symbol: mol) is the SI base unit that measures an amount of substance. One mole contains Avogadro's number (approximately 6.0221023) entities.
A mole is much like "a dozen" in that both are absolute numbers (having no units) and can describe any type of
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A mole is much like "a dozen" in that both are absolute numbers (having no units) and can describe any type of
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1 decimetre =
SI units
0 m 0 mm
US customary / Imperial units
0 ft 0 in
SI units
0 m 0 mm
US customary / Imperial units
0 ft 0 in
A decimetre (American spelling: decimeter, symbol dm
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kilogram or kilogramme (symbol: kg) is the SI base unit of mass. The kilogram is defined as being equal to the mass of the International Prototype Kilogram (IPK), which is almost exactly equal to the mass of one liter of water.
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In chemistry, the mole fraction of a component in a mixture is the relative proportion of molecules belonging to the component to those in the mixture, by number of molecules. It is one way of measuring concentration.
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Plimsoll is a surname, and may refer to:
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- Sir James Plimsoll, a governor of Tasmania
- John Plimsoll, South African cricketer
- Oliver Plimsolls, fictional character in The League of Gentlemen (comedy)
- Samuel Plimsoll, British politician
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In chemistry and other sciences, STP or standard temperature and pressure is a standard set of conditions for experimental measurements, to enable comparisons to be made between sets of data.
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