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The ideal gas equation can be rearranged to give an expression for the molar volume of an ideal gas: = = Hence, for a given temperature and pressure, the molar volume is the same for all ideal gases and is based on the gas constant: R = 8.314 462 618 153 24 m 3 ⋅Pa⋅K −1 ⋅mol −1, or about 8.205 736 608 095 96 × 10 −5 m 3 ⋅atm⋅K ...
In chemistry, the mole fraction or molar fraction, also called mole proportion or molar proportion, is a quantity defined as the ratio between the amount of a constituent substance, n i (expressed in unit of moles, symbol mol), and the total amount of all constituents in a mixture, n tot (also expressed in moles): [1]
Molar concentration or molarity is most commonly expressed in units of moles of solute per litre of solution. [1] For use in broader applications, it is defined as amount of substance of solute per unit volume of solution, or per unit volume available to the species, represented by lowercase : [2]
The molar ratio allows for conversion between moles of one substance and moles of another. For example, in the reaction 2 CH 3 OH + 3 O 2 → 2 CO 2 + 4 H 2 O. the amount of water that will be produced by the combustion of 0.27 moles of CH 3 OH is obtained using the molar ratio between CH 3 OH and H 2 O of 2 to 4.
It is the same concept as volume percent (vol%) except that the latter is expressed with a denominator of 100, e.g., 18%. The volume fraction coincides with the volume concentration in ideal solutions where the volumes of the constituents are additive (the volume of the solution is equal to the sum of the volumes of its ingredients).
In solutions, mass concentration is commonly encountered as the ratio of mass/[volume solution], or m/v. In water solutions containing relatively small quantities of dissolved solute (as in biology), such figures may be "percentivized" by multiplying by 100 a ratio of grams solute per mL solution. The result is given as "mass/volume percentage".
The molar concentration is defined as the amount of a constituent (in moles) divided by the volume of the mixture : =. The SI unit is mol/m 3. However, more commonly the unit mol/L (= mol/dm 3) is used.
This improper name persists, especially in elementary textbooks. In biology, the unit "%" is sometimes (incorrectly) used to denote mass concentration, also called mass/volume percentage. A solution with 1 g of solute dissolved in a final volume of 100 mL of solution would be labeled as "1%" or "1% m/v" (mass/volume). This is incorrect because ...