Molarity Calculator
Works out concentration in mol/L, or how much to weigh out. Choose what to find; the field for that value is ignored.
Answer
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Molarity — mol/L
Moles of solute — mol
Grams per litre — g/L
The formula
molarity = moles ÷ litres of solution moles = mass ÷ molar mass
Molarity is measured against the finished solution, so dissolve first and then make up to the mark.
What to watch out for
Molarity changes slightly with temperature because liquids expand. For a figure that does not, use molality.
Frequently Asked Questions
How much salt makes 250 mL of 0.4 mol/L solution?
0.4 × 0.25 × 58.44 = 5.84 g of sodium chloride, made up to 250 mL.
What does 1 M mean?
One mole of solute per litre of solution.