Mass percent

In chemistry, the mass fraction ${\displaystyle w_{i}}$ is the ratio of one substance with mass ${\displaystyle m_{i}}$ to the mass of the total mixture ${\displaystyle m_{\text{tot}}}$, defined as

The sum of all the mass fractions is equal to 1:

Mass fraction can also be expressed, with a denominator of 100, as percentage by mass (in commercial contexts often called percentage by weight, abbreviated wt%; see mass versus weight). It is one way of expressing the composition of a mixture in a dimensionless size; mole fraction (percentage by moles, mol%) and volume fraction (percentage by volume, vol%) are others.

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