Henry's Law Gas Solubility Calculator

Enter the partial pressure and Henry's constant (or pick a preset gas) to calculate the dissolved gas concentration in mol/L and mmol/L.

Created by Luis GonzalezLast updated: May 9, 2026

How to Use This Calculator

1
Enter Henry's Constant (kH) (mol/(L·atm))
Input the Henry's Law constant for your specific gas-solvent system at the given temperature. For CO₂, it's around 0.034 mol/(L·atm) at 25 °C.
2
Specify Partial Pressure (atm)
Enter the partial pressure of the gas above the liquid surface in atmospheres. Standard atmospheric pressure is 1 atm.
3
Input Temperature (°C)
Provide the solution temperature in Celsius. Higher temperatures generally decrease gas solubility (note: kH must be adjusted manually for precise temperature correction).
4
Review your results
The calculator will display the dissolved gas concentration in mol/L and mmol/L, partial pressure applied, Henry's constant, and saturation level.

Example Calculation

A scientist is studying CO₂ dissolution in water at 25 °C. They know Henry's constant for CO₂ is 0.034 mol/(L·atm) and the partial pressure of CO₂ above the water is 1 atm. They need to find the dissolved concentration.

Henry's Constant (kH) (mol/(L·atm))

0.034

Partial Pressure (atm)

Temperature (°C)

Results

0.034000 mol/L

Tips

Adjust kH for Temperature

Henry's constant (kH) is highly temperature-dependent. For precise results at temperatures other than the reference, ensure you use a kH value specific to your desired temperature, as solubility can change by 10-20% per 10°C.

Consider Gas Mixture

If working with a gas mixture (like air), calculate the partial pressure of the specific gas of interest. For example, oxygen's partial pressure in air is approximately 0.21 atm at standard conditions.

Account for Salinity

Gas solubility decreases significantly in saline solutions (like seawater) compared to pure water. If your solvent is not pure water, use a kH constant adjusted for salinity to avoid overestimating solubility.

Quantifying Dissolved Gases: Applying Henry's Law for Solubility Calculations

The Henry's Law Gas Solubility Calculator is a specialized tool for chemists, environmental scientists, and engineers to accurately determine the concentration of a dissolved gas in a liquid. It applies Henry's Law (C = kH × P) to calculate dissolved gas concentration, allowing users to input Henry's Constant (kH) and the gas's partial pressure. For instance, if a scientist is studying CO₂ in water at 25 °C, with a kH of 0.034 mol/(L·atm) and a partial pressure of 1 atm, the calculator will show a dissolved concentration of 0.034000 mol/L. This is fundamental for understanding gas exchange in natural systems and industrial processes.

Why Understanding Gas Solubility is Crucial in Chemistry

Gas solubility, governed by Henry's Law, is a critical phenomenon across various scientific and industrial domains. In environmental science, it dictates how gases like oxygen and carbon dioxide dissolve in natural waters, impacting aquatic life and climate regulation. In industrial processes, it's essential for designing gas scrubbers, fermentation reactors, and beverage carbonation systems. In medicine, it explains how anesthetic gases enter the bloodstream and how divers experience decompression sickness. Accurate calculations are vital for predicting behavior, ensuring safety, and optimizing processes where gas-liquid interfaces are involved.

The Henry's Law Formula for Gas Concentration

Henry's Law states that the concentration of a gas dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid. The proportionality constant is specific to each gas-solvent pair and temperature.

The core formula is:

C = kH × P

Where:

C is the dissolved concentration of the gas (e.g., in mol/L)
kH is Henry's Law constant (e.g., in mol/(L·atm))
P is the partial pressure of the gas above the solution (e.g., in atm) This simple linear relationship allows for direct calculation of dissolved gas concentration under varying pressure conditions.

💡 Understanding concentrations is fundamental in chemistry. Our Normality Calculator can help you determine another key measure of solution concentration.

Calculating Dissolved CO₂ in Water

Let's consider a scientist investigating CO₂ dissolution in water:

Input values: Henry's Constant (kH) = 0.034 mol/(L·atm), Partial Pressure (P) = 1 atm, Temperature = 25 °C.
Apply Henry's Law formula: C = 0.034 mol/(L·atm) × 1 atm
Calculate the result: C = 0.034 mol/L The dissolved concentration of CO₂ in water under these conditions is 0.034000 mol/L. This concentration corresponds to a moderate level of dissolution, typical for atmospheric CO₂ at standard pressure and temperature. The calculator also provides the equivalent in millimoles per liter (mmol/L) and contextualizes the saturation level.

💡 Just as gas solubility is a physical property, nuclear decay is a fundamental process. Our Nuclear Half-Life Calculator helps determine the time required for radioactive substances to decay.

Industry Benchmarks for Henry's Law Constant (kH)

Henry's Law constant (kH) varies significantly for different gases and solvents, making specific benchmarks crucial for practical applications. These values are typically reported at a standard temperature (e.g., 25 °C) and are often found in chemical handbooks.

Carbon Dioxide (CO₂) in water: kH ≈ 0.034 mol/(L·atm) at 25 °C. This relatively high value explains why CO₂ readily dissolves in beverages and oceans.
Oxygen (O₂) in water: kH ≈ 0.0013 mol/(L·atm) at 25 °C. Oxygen is much less soluble than CO₂, but vital for aquatic life.
Nitrogen (N₂) in water: kH ≈ 0.0006 mol/(L·atm) at 25 °C. Nitrogen is even less soluble than oxygen, which is relevant for divers and decompression sickness.
Hydrogen Sulfide (H₂S) in water: kH ≈ 0.1 mol/(L·atm) at 25 °C. This gas is highly soluble, contributing to its toxicity even at low partial pressures. These benchmarks highlight the wide range of gas solubilities and their implications for various chemical, environmental, and biological systems.

Frequently Asked Questions

What is Henry's Law and what does it describe?

Henry's Law is a gas law that states the amount of dissolved gas in a liquid is directly proportional to the partial pressure of that gas above the liquid. In simpler terms, the higher the pressure of a gas above a liquid, the more of that gas will dissolve into the liquid. This law is fundamental for understanding phenomena like carbonation in beverages and gas exchange in biological systems.

What is Henry's Law constant (kH) and why is it important?

Henry's Law constant (kH) is a proportionality constant specific to each gas-solvent pair and temperature. It quantifies how soluble a gas is in a particular liquid under a given pressure. A higher kH value indicates greater solubility. This constant is crucial for predicting dissolved gas concentrations in environmental science, industrial processes, and clinical applications, varying significantly (e.g., CO₂'s kH is about 26 times higher than O₂'s in water).

How does temperature affect gas solubility according to Henry's Law?

While Henry's Law itself doesn't explicitly include temperature in its primary formula, the Henry's Law constant (kH) is highly temperature-dependent. For most gases, solubility in liquids decreases as temperature increases. This is why carbonated drinks go flat faster when warm and why aquatic life struggles in warmer waters due to lower dissolved oxygen levels, with kH values often decreasing by 1-2% per degree Celsius increase.

What are some real-world applications of Henry's Law?

Henry's Law has numerous real-world applications. It explains why carbonated beverages fizz when opened (decreasing pressure reduces dissolved CO₂). In diving, it's critical for understanding how nitrogen dissolves in blood under high pressure and then comes out of solution during ascent (decompression sickness). It's also used in environmental science to model gas exchange between the atmosphere and oceans, and in industrial processes for gas absorption.