Molarity Calculator

Molarity From Density Calculator

This molarity from density calculator converts the density and purity of a liquid reagent into molar concentration. Enter the density (g/mL), purity percentage (%), and molar mass (g/mol) to compute molarity. Essential for working with concentrated liquid acids and bases.

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Molarity From Density Calculator

Density × Purity → Molarity

Formula
M = (density × 1000 × purity%) / MW
Live Preview
Density
Purity (%)
Molar Mass
Molarity (M)
How It Works
1
Density
Enter value
2
Purity (%)
Enter value
3
Molar Mass
Enter value
Molarity (M)

What is Molarity From Density?

Molarity from density calculates the molar concentration of a pure or concentrated liquid chemical from its physical density and purity. This is how you determine the molarity of reagent bottles that list density and assay percentage.

The formula converts volume-based density (g/mL) to moles/L using the molar mass. For impure solutions, the purity percentage adjusts for the actual solute fraction.

This calculation is standard for concentrated acids (H₂SO₄, HCl, HNO₃) and bases (NaOH, NH₃) that are supplied as liquids with known density and purity on the label.

Molarity = (density × 1000 × purity%) ÷ molar mass
Visual Concept
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Density → Molarity
Concentration measured in moles per liter (mol/L)
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Unit: M (Molar)
1 M = 1 mol of solute per 1 liter of solution
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Key Relationship
Molarity = Moles of Solute ÷ Volume of Solution

Molarity From Density Formula

The formula for calculating molarity from density:

molarity = moles of solute ÷ volume of solution (L)

To use this formula, you need density and molar mass. The calculator handles all unit conversions automatically.

Enter your values below to see the molarity from density formula in action.

mass ÷ volume = concentration = molarity × molar mass

Where mass is in grams (g), volume is in liters (L), and molar mass is in g/mol.

Formula Breakdown
M = (ρ × P × 10) / MW
M
Molarity (mol/L)
ρ
Density (g/mL)
P
Mass percentage (%)
MW
Molar mass (g/mol)
💡 Density and purity together determine the concentration

How to Calculate Molarity From Density

Follow these steps to calculate molarity from density:

  1. Identify the density of your solute and gather all known values.
  2. Find the molar mass of the substance from the periodic table or a chemical database.
  3. Enter your density value and select the appropriate unit from the dropdown.
  4. Enter the volume of the solution in liters (L) or select another volume unit.
  5. Click Calculate to get the molarity result instantly.
  6. Verify the result using the step-by-step breakdown provided by the calculator.
Step-by-Step Process
1
🪨
Measure Density
Find or measure density ρ (g/mL)
2
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Know Purity
Find mass percentage P from label
3
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Find MW
Look up molecular weight
4
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Apply Formula
M = (ρ × P × 10) / MW
5
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Check Units
Verify consistent units throughout
6
Result
Molarity in mol/L

Molarity From Density Calculator Examples

The examples below show how to use the molarity from density calculator in practice.

Example 1: What is the molarity of pure water? Density of water ≈ 1 g/mL, molar mass = 18.015 g/mol. M = 1000/18.015 ≈ 55.5 M.

Example 2: Using the formula: molarity = moles ÷ volume, compute the result and verify with the calculator above.

Example 3: Enter your own values into the calculator to see personalized step-by-step results.

Worked Example Example: HNO₃ from Density
Density 1.42 g/mL
Purity 70 %
MW 63 g/mol
Molarity 15.78 M

Molarity Calculator Tools

Explore our collection of 20 specialized molarity calculators. Each tool is designed for a specific type of calculation with its own unique input fields and formulas.

FAQs

How do you convert density to molarity?

Molarity = (density × 1000 × purity fraction) ÷ molar mass. For pure substances, purity = 1.

What is the molarity of pure water?

Density of water ≈ 1 g/mL, molar mass = 18.015 g/mol. M = 1000/18.015 ≈ 55.5 M.

Does temperature affect density-based molarity?

Yes. Density changes with temperature, so molarity calculated from density also varies with temperature.

What units does the Molarity From Density Calculator support?

The molarity from density calculator supports mass units (g, mg, µg, kg), volume units (L, mL, µL, gal), molar mass (g/mol, kg/mol), and molarity units (M, mM, µM, nM, pM, fM, aM).

Is the Molarity From Density Calculator free to use?

Yes. The molarity from density calculator is 100% free, requires no sign-up, and works on all devices. All calculations are performed instantly in your browser.