What is the Mass to Molarity Calculator?
This calculator converts a known mass of solute into a molar concentration (molarity, symbol M) for a solution of a given volume. Molarity expresses how many moles of dissolved substance are present per liter of solution and is one of the most common units in chemistry, biology, and laboratory work.
How to use it
Enter three values: the mass of solute in grams, the molecular weight (molar mass) of the compound in g/mol, and the volume of solution along with its unit (L, mL or µL). The tool first converts the mass to moles, then divides by the volume in liters to return molarity in mol/L.
The formula explained
The calculation has two steps. First, moles of solute: \(n = \dfrac{\text{mass}}{\text{MW}}\). Second, molarity: \(M = \dfrac{n}{V}\), where \(V\) is the volume expressed in liters. Combined, $$M = \frac{\dfrac{\text{mass}}{\text{MW}}}{V_{(L)}}$$ Because molarity is per liter, any volume entered in mL or µL is automatically converted (mL ÷ 1000, µL ÷ 1,000,000).
Worked example
To prepare 1 L of a sodium chloride (NaCl) solution using 5 g of NaCl (MW = 58.44 g/mol): $$\text{moles} = \frac{5}{58.44} = 0.08556 \text{ mol}.$$ $$\text{Molarity} = \frac{0.08556}{1} = \textbf{0.0856 M}.$$ That is roughly a 0.086 molar saline solution.
FAQ
What is molecular weight? It is the mass of one mole of a compound in grams per mole, found by summing the atomic weights of all atoms in the formula.
Can I enter volume in mL? Yes — select mL or µL and the calculator converts to liters automatically before computing molarity.
What is the difference between molarity and molality? Molarity is moles per liter of solution; molality is moles per kilogram of solvent. This tool computes molarity.
