Molar fraction

The molar fraction of a component i in a mixture is defined as:

Failed to parse (Conversion error. Server ("https://wikimedia.org/api/rest_") reported: "Cannot get mml. Server problem."): {\displaystyle X_{i}={\frac {n_{i}}{\sum _{j=1}^{N}n_{j}}}}

where Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle n_i } is the number of moles of component i.