100 ppm corresponds to approximately 0.0016 molarity for a substance with a molar mass of 62.44 g/mol (like sodium chloride). This means that 100 mg of solute per liter solution is about 0.0016 moles per liter.
The conversion from ppm (parts per million) to molarity depends on the molar mass of the solute and the density of the solution. By considering 1 ppm as 1 mg/L and converting mass to moles, we get the molarity.
Conversion Tool
Result in molarity:
Conversion Formula
The formula to convert ppm to molarity is derived from the relationship between mass and moles. Ppm means milligrams of solute per liter of solution (mg/L). To find molarity, first convert the milligrams to grams by dividing by 1000, then divide by the molar mass (grams per mole) to get moles per liter.
Formula:
Molarity (mol/L) = (ppm / 1000) / Molar Mass (g/mol)
Example: For 100 ppm of NaCl with molar mass 62.44 g/mol:
Step 1: Convert ppm to grams per liter: 100 ppm = 100 mg/L = 0.1 g/L
Step 2: Divide grams by molar mass: 0.1 g/L ÷ 62.44 g/mol ≈ 0.0016 mol/L
So, 100 ppm NaCl ≈ 0.0016 M
Conversion Example
- Convert 50 ppm of NaCl to molarity:
– 50 ppm = 50 mg/L = 0.05 g/L
– 0.05 g / 62.44 g/mol = 0.0008 mol/L - Convert 200 ppm of NaCl:
– 200 mg/L = 0.2 g/L
– 0.2 g / 62.44 g/mol = 0.0032 mol/L - Convert 125 ppm of NaCl:
– 125 mg/L = 0.125 g/L
– 0.125 g / 62.44 g/mol ≈ 0.0020 mol/L - Convert 80 ppm of NaCl:
– 80 mg/L = 0.08 g/L
– 0.08 g / 62.44 g/mol ≈ 0.0013 mol/L
Conversion Chart
| ppm (mg/L) | Molarity (mol/L) |
|---|---|
| 75.0 | 0.0012 |
| 80.0 | 0.0013 |
| 85.0 | 0.0014 |
| 90.0 | 0.0014 |
| 95.0 | 0.0015 |
| 100.0 | 0.0016 |
| 105.0 | 0.0017 |
| 110.0 | 0.0018 |
| 115.0 | 0.0018 |
| 120.0 | 0.0019 |
| 125.0 | 0.0020 |
The chart shows ppm values and their equivalent molarity based on NaCl molar mass 62.44 g/mol. You can find your ppm value, then read across to find molarity without calculation.
Related Conversion Questions
- How to convert 100 ppm salt concentration to molar solution?
- What is molarity when sodium chloride concentration is 100 ppm?
- Is 100 ppm equivalent to 0.0016 molar for NaCl?
- How do I calculate molarity from a 100 ppm aqueous solution?
- What molar concentration corresponds to 100 ppm in water?
- How many moles per liter are in a 100 ppm salt solution?
- Can 100 ppm be converted directly to molarity for any substance?
Conversion Definitions
ppm: Ppm means parts per million, a unit measuring concentration. It express the ratio of a substance in a mixture as milligrams of solute per liter of solution. It is used to quantify very dilute concentrations in liquids, gases, or solids.
Molarity: Molarity is a concentration unit measuring moles of solute per liter of solution. It expresses how many molecules or atoms of a substance dissolved in a volume of liquid. Molarity is used in chemical reactions to relate amounts precisely.
Conversion FAQs
Does the density of the solution affect ppm to molarity conversion?
Yes, if the solution density differs from water (1 g/mL), the ppm to molarity conversion changes. Ppm assumes mg per liter of solution, but if density varies, the volume-to-mass ratio shifts, affecting molarity. For accurate results, the solution density must be known.
Can ppm be directly converted to molarity without molar mass?
No, molar mass is necessary because ppm is a mass-based unit, while molarity is mole-based. Without knowing the molar mass, you cannot convert mass units to moles, so molar mass is required for any ppm to molarity calculation.
Why is 100 ppm NaCl approximately 0.0016 M?
This comes from converting 100 mg/L (ppm) to grams per liter (0.1 g/L), then dividing by NaCl molar mass 62.44 g/mol, yielding 0.0016 mol/L. This ratio comes from molecular weight relating grams to moles.
Is the ppm to molarity conversion valid for gases?
Not exactly. Ppm for gases often refers to volume or mole fraction, not mass per volume. So converting gaseous ppm to molarity requires gas laws and conditions like temperature and pressure, making it more complex than liquid solutions.
How precise is the ppm to molarity conversion in real solutions?
The precision depends on assumptions like solution density and purity. For dilute aqueous solutions, approximation assuming density 1 g/mL is fine, but deviations in density or solute interactions can cause slight errors in calculated molarity.
Last Updated : 22 July, 2025
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Sandeep Bhandari holds a Bachelor of Engineering in Computers from Thapar University (2006). He has 20 years of experience in the technology field. He has a keen interest in various technical fields, including database systems, computer networks, and programming. You can read more about him on his bio page.