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Constantin Budeanu was a Romanian electrical engineer born in 1886.In 1903-1908 the National School of Bridges and Highways in Bucharest, Romanian Railways and the Bucharest Tram Society technical director of the Electrical Society in Bucharest.

In 1916 became professor of Electrical Measurements and Electrical Engineering in the Electricity and Electrical Engineering department of the National School of Bridges and Highways, being assistant to Nicolae Vasilescu Karpen.

${\displaystyle {\bar {M}}=\sum _{i}x_{i}M_{i}\,}$

It can also be calculated from the mass fractions ${\displaystyle w_{i}}$ of the components:

${\displaystyle 1/{\bar {M}}=\sum _{i}{\frac {w_{i}}{M_{i}}},}$

${\displaystyle x_{i}={\frac {\frac {m_{i}}{M_{i}}}{\sum _{i}{\frac {m_{i}}{M_{i}}}}},}$

The relation between mass concentration ${\displaystyle \rho _{i}}$ and molar concentration is:

${\displaystyle {\boldsymbol {\rho _{i}}}=c_{i}\cdot M_{i}}$

where ${\displaystyle M_{i}}$ is the molar mass of constituent ${\displaystyle i}$.

${\displaystyle \rho \cdot w_{i}=c_{i}\cdot M_{i}}$

${\displaystyle w_{i}={\frac {1}{1+1/(m_{i}\cdot M_{i})}}}$

${\displaystyle c_{i}=\rho \cdot {\frac {m_{i}}{1+m_{i}\cdot M_{i}}}}$

${\displaystyle m_{i}={\frac {c_{i}}{(\rho -c_{i}\cdot M_{i})}}\,}$

${\displaystyle {\frac {c_{i}}{c_{i}\cdot (\rho -c_{i}\cdot M_{i})}}=m_{i}\,}$ or

The sum of the molar concentrations of all components (including the solvent) gives the multiplicative inverse of the molar volume of the mixture or the molar density ${\displaystyle \rho }$ of the solution:

${\displaystyle {\frac {\rho }{\bar {M}}}=\sum _{i}c_{i}\,}$

Thus, for pure component the molar concentration equals the molar density of the mixture namely density divided by average molar mass of the mixture M.

Molar concentration is the product of the density of a solution and the mole fraction ${\displaystyle w_{i}}$ of a component:

${\displaystyle {\frac {\rho _{i}}{M_{i}}}={\frac {\rho }{M}}\cdot x_{i}}$

• Volume fraction
• Volume percent
• Volume concentration
• Molality

In order to avoid confusion and also to underline the significance (the connection between the two quantities mass concentration and mass density), the best solution is to use bolded rho or ${\displaystyle \varrho _{i}\,}$ for mass concentration while keeping the unmodified rho for mass density. This implies that any other Wikipedia requirements which might be contrary to this purpose be ignored.

${\displaystyle \rho =\sum _{i}\varrho _{i}\,}$

${\displaystyle V\approx V_{0}(1+\alpha \cdot \Delta T)}$

${\displaystyle \rho ={\frac {\rho ^{0}}{(1+\alpha \cdot \Delta T)}}}$

Expressed as a function of the densities of pure components of the mixture and their volume participation, it reads:

${\displaystyle \rho =\sum _{i}\rho _{i}^{*,0}{\frac {V_{i}}{V}}\,=\rho _{i}^{*}{\frac {n_{i}V_{i}^{*}}{V}}\,}$

${\displaystyle \rho _{i}=\varrho _{i}{\frac {V_{i}}{V}}\,=\rho _{i}^{*}{\frac {n_{i}V_{i}^{*}}{V}}\,}$

${\displaystyle \alpha _{i}=\sum _{i}x_{i}\cdot {\frac {\bar {V_{i}}}{\tilde {V}}}\cdot {\bar {\alpha _{i}}}}$

${\displaystyle \alpha _{i}=\sum _{i}c_{i}\cdot {\bar {V_{i}}}\cdot {\bar {\alpha _{i}}}}$

${\displaystyle 1=\sum _{i}c_{i}\cdot {\bar {V_{i}}}}$

${\displaystyle \phi _{i}={\frac {V_{i}}{\sum _{i}V_{i}}}={\frac {\varphi _{i}}{1-\sum _{i}\phi _{i}^{e}}}}$

• Fick's laws of diffusion
• Concentration gradient
• Transport phenomena
• Mass transfer
• Maxwell-Stefan diffusion

[1]

http://en.wikipedia.org/wiki/Special:Contributions/V8rik http://en.wikipedia.org/wiki/Special:Contributions/Smokefoot http://en.wikipedia.org/wiki/Special:Contributions/Itub http://en.wikipedia.org/wiki/Special:Contributions/Wtshymanski