Density Calculator
Calculate the density of any substance using ρ = m/V, or solve for mass or volume. Fast physics calculator with results in kg/m³ and g/cm³ — free online tool.
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Solution Concentration Calculator (% and mol/dm³)
The solution concentration calculator lets you quickly compute either the percentage (mass) concentration or the molar concentration of any chemical solution. Percentage concentration (Cp) expresses the mass of dissolved substance per 100 g of solution — the most intuitive way to describe a solution, widely used in everyday life, food industry and basic chemistry. Molar concentration (Cm) tells you how many moles of substance are dissolved per litre (dm³) of solution, making it the standard metric in stoichiometry, analytical chemistry and laboratory work. The calculator offers three modes for percentage concentration: calculate concentration from solute and solution mass, find the solute mass needed to reach a target concentration, and find the solution mass for a given solute mass and concentration. For molar concentration it first computes the number of moles (n = mass / molar mass) and then the molarity (Cm = n / volume). This tool is ideal for high-school and university chemistry students, lab technicians and anyone who prepares solutions at home or at work. Simply select the concentration type, fill in the fields and click "Calculate" — the result appears instantly. No registration required.
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How we calculate solution concentration
Mass percentage concentration is calculated as: Cp = (mSolute / mSolution) × 100%. The solution mass is the sum of solute mass and solvent mass. Inverse formulae: mSolute = Cp × mSolution / 100 and mSolution = mSolute × 100 / Cp. Molar concentration is calculated in two steps. First, the number of moles: n = massSolute / molarMass [mol]. Then the molar concentration: Cm = n / V [mol/dm³], where V is the solution volume in dm³. The calculator guards against division by zero — if the solution mass or volume is 0 the result is 0. Results are rounded to four decimal places for readability.
Example: sodium chloride (NaCl) in water
Example 1 — percentage concentration: We dissolve 10 g of NaCl in water to obtain 100 g of solution. Percentage concentration: Cp = (10 / 100) × 100% = 10%. This is a common saline rinse concentration. Example 2 — molar concentration: The molar mass of NaCl is 58.5 g/mol. If we dissolve 5.85 g of NaCl and make the volume up to 1 dm³, the number of moles n = 5.85 / 58.5 = 0.1 mol, so the molar concentration Cm = 0.1 / 1 = 0.1 mol/dm³. Example 3 — finding solute mass: To prepare 500 g of a 20% solution, solute mass = 20 × 500 / 100 = 100 g — that is the amount you need to weigh out.
Frequently asked questions about solution concentration
What is the difference between percentage and molar concentration?
Percentage concentration (Cp) expresses the solute mass per 100 g of solution in percent. Molar concentration (Cm) expresses the number of moles of solute per 1 dm³ of solution in mol/dm³. Percentage concentration is easy to prepare in practice, while molar concentration is preferred for stoichiometric calculations and chemical reactions.
How do I calculate percentage concentration?
Use the formula: Cp = (mSolute / mSolution) × 100%. The solution mass is the sum of solute and solvent masses. For example, 20 g NaCl in 200 g solution: Cp = (20/200) × 100% = 10%.
How do I calculate molar concentration?
Molar concentration Cm = n / V, where n is the number of moles (n = mass / molar mass) and V is the solution volume in dm³. For example, 5.85 g NaCl (molar mass 58.5 g/mol) in 1 dm³: n = 0.1 mol, Cm = 0.1 mol/dm³.
What is a saturated solution?
A saturated solution is one in which the maximum amount of substance has been dissolved at a given temperature and pressure. Adding more substance does not increase its concentration — the excess remains as a precipitate. For example, at 20°C the maximum NaCl concentration is about 26.3%.
How do I dilute a solution to a desired concentration?
Use the dilution formula: C1 × V1 = C2 × V2, where C1 and V1 are the initial concentration and volume, and C2 and V2 are the target values. For example, to get 0.1 mol/dm³ from a 1 mol/dm³ solution in 1 dm³ total volume, take 0.1 dm³ of the original and add water to 1 dm³.
How do I convert percentage concentration to molar concentration?
Cm = (Cp × density × 10) / M, where Cp is the percentage concentration [%], density is the solution density [g/cm³] and M is the molar mass [g/mol]. The factor 10 converts units (g/cm³ × dm³ = 1000 g/L, divided by 100 for percent).
What are typical concentrations in everyday life?
Examples: table vinegar — about 5–10% acetic acid; pharmacy hydrogen peroxide — 3% H₂O₂; physiological saline — 0.9% NaCl; disinfecting alcohol — 70–96% ethanol. These are mass-percentage or volume-percentage concentrations depending on context.
What is molar mass and how do I find it?
Molar mass is the mass of one mole of a substance expressed in g/mol. It equals the sum of the atomic masses of all atoms in a molecule. For NaCl: Na (22.99) + Cl (35.45) = 58.44 g/mol. Atomic masses are found in the periodic table.
Why is volume used instead of mass for molar concentration?
Volume is used for molar concentration because it simplifies measurement with laboratory glassware (pipettes, volumetric flasks) and enables direct use in kinetics and chemical equilibrium equations, where the number of molecules per unit volume is what matters.
How does concentration affect solution properties?
Concentration directly affects colligative properties: higher concentration lowers the freezing point, raises the boiling point and increases osmotic pressure. This is important for antifreeze agents, food preservation and intravenous drug administration.
Results are for informational and educational purposes. The calculator assumes ideal mixing — in practice the solution volume may differ from the sum of component volumes. Before laboratory use, follow the appropriate analytical procedure.