1. What is mg/m³ to ppm Conversion?

Definition: This calculator converts concentration measurements from milligrams per cubic meter (mg/m³) to parts per million (ppm).

Purpose: It's essential for air quality measurements, industrial hygiene, and chemical concentration analysis where different units are required.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• ppm — Parts per million (volume/volume)
• mg/m³ — Mass concentration (milligrams per cubic meter)
• 24.45 — Molar volume of air at 25°C (liters per mole)
• Molecular Weight — Molecular weight of the substance (grams per mole)

Explanation: The formula converts mass concentration to volume concentration using the ideal gas law and molar volume.

3. Importance of Unit Conversion

Details: Many regulations and standards specify limits in ppm, while instruments often measure in mg/m³. Accurate conversion is crucial for compliance and safety.

4. Using the Calculator

Tips: Enter the concentration in mg/m³ and the molecular weight of the substance in g/mol. Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is 24.45 used in the formula?
A: It's the molar volume (in liters) of an ideal gas at 25°C (298K) and 1 atmosphere pressure.

Q2: Does temperature affect the conversion?
A: Yes, the 24.45 factor is for 25°C. For other temperatures, use: 24.45 × (298/T), where T is temperature in Kelvin.

Q3: Where can I find molecular weights?
A: Chemical reference tables or periodic tables provide molecular weights (e.g., O₂ = 32, CO₂ = 44).

Q4: What's the difference between ppm and mg/m³?
A: ppm is volume/volume, while mg/m³ is mass/volume. The relationship depends on the gas's molecular weight.

Q5: Can I convert ppm back to mg/m³?
A: Yes, use: mg/m³ = (ppm × Molecular Weight) / 24.45