PPM to Molarity Calculator

Convert parts per million (ppm) to molarity (M) or vice versa. Enter the concentration in ppm and the molar mass of the solute to calculate molar concentration.

Concentration in ppm

Molecular weight of the solute

Concentration in mol/L

PPM to Molarity Formula: Molarity (M) = ppm / (Molar Mass × 1000) Where: • ppm = parts per million (mg/L for aqueous solutions) • Molar Mass = molecular weight in g/mol • 1000 converts L to mL basis Reverse Calculation: ppm = Molarity × Molar Mass × 1000 Percent by Mass: % = ppm / 10000
Example 1 (Sodium Chloride): PPM = 1000 ppm Molar Mass of NaCl = 58.44 g/mol Molarity = 1000 / (58.44 × 1000) = 0.0171 M = 17.1 mM Example 2 (Glucose in water): PPM = 50 ppm Molar Mass of Glucose = 180.16 g/mol Molarity = 50 / (180.16 × 1000) = 2.78×10⁻⁴ M = 0.278 mM Example 3 (Reverse - Molarity to PPM): Molarity = 0.1 M Molar Mass = 40 g/mol (Ca(OH)₂) PPM = 0.1 × 40 × 1000 = 4000 ppm Example 4 (Trace metal ion): Copper concentration = 5 ppm in water Molar Mass of Cu = 63.55 g/mol Molarity = 5 / (63.55 × 1000) = 7.87×10⁻⁵ M = 78.7 µM

What is ppm in chemistry?

PPM (parts per million) is a dimensionless ratio that measures the mass of a substance per million units of total mass. For aqueous solutions, 1 ppm ≈ 1 mg/L since 1 liter of water weighs approximately 1 kg (1,000,000 mg).

How do you convert ppm to molarity?

Use the formula: Molarity (M) = ppm / (Molar Mass × 1000). For example, to convert 100 ppm of NaCl (molar mass = 58.44 g/mol): M = 100 / (58.44 × 1000) = 0.00171 M = 1.71 mM.

Why do I need molar mass for ppm conversion?

PPM measures mass ratio while molarity measures moles per liter. To convert between them, you need to know how many grams are in one mole of the substance (molar mass). Different substances have different molar masses, so the conversion factor differs.

What is the relationship between ppm and molarity for water?

For dilute aqueous solutions, 1 ppm ≈ 1 mg/L. Since 1 L of water = 1 kg = 1,000,000 mg, the conversion is: M = ppm / (MW × 1000). For very dilute solutions, this approximation is accurate.

How do I convert ppm to mg/L?

For aqueous solutions, ppm and mg/L are essentially equivalent because 1 L of water ≈ 1 kg = 1,000,000 mg. So 50 ppm = 50 mg/L. This is a valid approximation for environmental and biological applications.

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