How to use the dissolved co₂ and water ph calculator
Estimate the pH of water in equilibrium with the air at a given CO₂ level, from Henry law and carbonic acid. Enter co₂ partial pressure, first acid dissociation constant of carbonic acid in the fields above; the dissolved co₂, hydrogen ion concentration, ph are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “pH of rainwater”, “CO2 dissolved in water pH”, “carbonic acid pH”, “calculate dissolved co₂ and water ph”, “find dissolved co₂”.
Formula
Variables
- pco2 — CO₂ partial pressure (ppm)
- K1 — First acid dissociation constant of carbonic acid
Worked example
With co₂ partial pressure = 420 ppm, first acid dissociation constant of carbonic acid = 4.3e-7, the calculator gives dissolved co₂ ≈ 1.428 × 10⁻⁵ mol/L; hydrogen ion concentration ≈ 2.478 × 10⁻⁶ mol/L; ph ≈ 5.605902 pH.
Frequently asked questions
What is the dissolved co₂ and water ph calculator used for?
Estimate the pH of water in equilibrium with the air at a given CO₂ level, from Henry law and carbonic acid. It helps with questions such as “pH of rainwater”, “CO2 dissolved in water pH”, “carbonic acid pH”.
What is the formula for the dissolved co₂ and water ph calculation?
Dissolved CO₂ (mol/L) = 0.034 × pco2 / 1e6. Hydrogen ion concentration (mol/L) = √(K1 × [Dissolved CO₂]). pH (pH) = -log10([Hydrogen ion concentration]). Here pco2 is co₂ partial pressure (ppm), K1 is first acid dissociation constant of carbonic acid.
What inputs do I need for the dissolved co₂ and water ph calculator?
You need co₂ partial pressure in ppm, first acid dissociation constant of carbonic acid. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the dissolved co₂ and water ph calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the dissolved co₂ and water ph result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.