Molar Concentration

The molar concentration cx of a solution of a solute species X is the number of moles of that species that is contained in 1 liter of the solution (not 1 L of the solvent). In terms of the number of moles of solute, n, and the volume, V, of solution, we write

The unit of molar concentration is molar, symbolized by M, which has the dimensions of mol/L, or mol L^-1. Molar concentration is also the number of millimoles of solute per milliliter of solution.

Example: Calculate the molar concentration of ethanol in an aqueous solution that contains

2.30 g of C₂H₅OH (46.07 g/mol) in 3.50 L of solution.

Solution

To calculate molar concentration, we must find both the amount of ethanol and the volume of the solution. The volume is given as 3.50 L, so all we need to do is convert the mass of ethanol to the corresponding amount of ethanol in moles.