how to find molar concentration

Molar Solution Concentration Calculator

Calculators for preparing physiological and biochemical solutions

Meant to be used in both the teaching and research laboratory, this calculator (see below) can be utilized to perform a number of different calculations for preparing molar solutions when starting with the solid material. For example, the known molecular weight of a chemical can be used along with the desired solution volume and solute concentration to determine the mass of chemical needed to make such a solution. On the other hand, if the desired concentration is known, but only a small amount (i.e., mass) of the chemical is available (such as when a very small amount is purchased, e.g., 10 mg), then the total solution volume can be calculated in which the solid material must be dissolved to achieve the desired final concentration.

Molar solution concentration equation

Molar Concentration Equation

C is the molar concentration in mol/L (Molar or M). This is also referred to as molarity, which is the most common method of expressing the concentration of a solute in a solution. Molarity is defined as the number of moles of solute dissolved per liter of solution (mol/L = M). A 1 M solution is one in which exactly 1 mole of solute is dissolved in a total solution volume of exactly 1 L. Using SI prefixes, the concentration may also be expressed in different fractions of the molar concentration such as mmol/L (mM), μmol/L (μM), nmol/L (nM), pmol/L (pM), etc.
m is the mass (i.e., weight) of solute in grams (g) that must be dissolved in volume V of solution to make the desired molar concentration (C).
V is volume of solution in liters (L) in which the indicated mass (m) of solute must be dissolved to make the desired molar concentration (C). Note that V is the final or total volume of solution after the solute has been added to the solvent.
MW is the molecular weight in g/mol. Molecular weight is also referred to as formula weight and, in fact, many scientists prefer to use the latter. The molecular weight can be obtained from the molecular formula, data tables, or the label on the bottle containing the chemical of interest.

Molar solution concentration calculator

Each calculator cell shown below corresponds to a term in the formula presented above. Enter appropriate values in all cells except the one you wish to calculate. Therefore, at least three cells must have values, and no more than one cell may be blank. The value of the blank cell will be calculated based on the other values entered. After a calculation is performed, the calculated cell will be highlighted and subsequent calculations will calculate the value of the highlighted cell (with no requirement to have a blank cell). However, a blank cell has priority over a highlighted cell.

For convenience, this worksheet allows you to select different mass, volume, and concentration units, and the necessary conversions are carried out for you to obtain the value of the blank cell in the desired unit. Note that the unit of molecular weight must be g/mol.

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Posted: Thursday, March 1, 2001

Last updated: Saturday, December 23, 2017