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Chemical reactions
K2CO3 + CO2 + H2O → 2KHCO3

K₂CO₃ + CO₂ + H₂O → 2KHCO₃

Last updated: March 20, 2023

Reaction of potassium carbonate, carbon dioxide, and water: K₂CO₃Potassium carbonate + CO₂Carbon dioxide + H₂OWater
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2KHCO₃Potassium hydrogencarbonate

The reaction of potassium carbonate, carbon dioxide, and water yields potassium hydrogencarbonate. This reaction is an acid-base reaction and is classified as follows:

Reaction of salt and acidic oxide with generating acid salt

Table of contents

Reaction data

Reactants

Chemical formula	Name	Coefficient	Type	Type in general equation
K₂CO₃	Potassium carbonate	1	Brønsted base	Salt
CO₂	Carbon dioxide	1	Lewis acid	Acidic oxide
H₂O	Water	1	–	Water

Products

Chemical formula	Name	Coefficient	Type	Type in general equation
KHCO₃	Potassium hydrogencarbonate	2	–	Acid salt

Thermodynamic changes

Changes in standard condition

Reaction of potassium carbonate, carbon dioxide, and water ◆ Δ_rG −32.0 kJ/mol K 4.04 × 10⁵ pK −5.61: K₂CO₃Crystalline solid + CO₂Gas + H₂OLiquid
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2KHCO₃Crystalline solid

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	−96.0	−32.0	−208.2	–
per 1 mol of Potassium carbonate	−96.0	−32.0	−208.2	–
per 1 mol of Carbon dioxide	−96.0	−32.0	−208.2	–
per 1 mol of Water	−96.0	−32.0	−208.2	–
per 1 mol of Potassium hydrogencarbonate	−48.0	−16.0	−104.1	–

Changes in aqueous solution

Reaction of potassium carbonate, carbon dioxide, and water ◆ Δ_rG −22.61 kJ/mol K 9.14 × 10³ pK −3.96: K₂CO₃Ionized aqueous solution + CO₂Un-ionized aqueous solution + H₂OLiquid
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2KHCO₃Ionized aqueous solution

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	−7.21	−22.61	51.8	–
per 1 mol of Potassium carbonate	−7.21	−22.61	51.8	–
per 1 mol of Carbon dioxide	−7.21	−22.61	51.8	–
per 1 mol of Water	−7.21	−22.61	51.8	–
per 1 mol of Potassium hydrogencarbonate	−3.60	−11.30	25.9	–

Thermodynamic data of reactants

Chemical formula	Standard enthalpy of formation Δ_fH° kJ · mol⁻¹	Standard Gibbs energy of formation Δ_fG° kJ · mol⁻¹	Standard molar entropy S° J · K⁻¹ · mol⁻¹	Standard molar heat capacity at constant pressure C_p° J · K⁻¹ · mol⁻¹
K₂CO₃ (cr)	-1151.02^[1]	-1063.5^[1]	155.52^[1]	114.43^[1]
K₂CO₃ (ai)	-1181.90^[1]	-1094.36^[1]	148.1^[1]	–
K₂CO₃ (cr) 1.5 hydrate	-1609.2^[1]	-1432.5^[1]	203.3^[1]	–
CO₂ (g)	-393.509^[1]	-394.359^[1]	213.74^[1]	37.11^[1]
CO₂ (ao)	-413.80^[1]	-385.98^[1]	117.6^[1]	–
H₂O (cr)	–	–	–	–
H₂O (l)	-285.830^[1]	-237.129^[1]	69.91^[1]	75.291^[1]
H₂O (g)	-241.818^[1]	-228.572^[1]	188.825^[1]	33.577^[1]

* (cr):Crystalline solid, (ai):Ionized aqueous solution, (g):Gas, (ao):Un-ionized aqueous solution, (l):Liquid

Thermodynamic data of products

Chemical formula	Standard enthalpy of formation Δ_fH° kJ · mol⁻¹	Standard Gibbs energy of formation Δ_fG° kJ · mol⁻¹	Standard molar entropy S° J · K⁻¹ · mol⁻¹	Standard molar heat capacity at constant pressure C_p° J · K⁻¹ · mol⁻¹
KHCO₃ (cr)	-963.2^[1]	-863.5^[1]	115.5^[1]	–
KHCO₃ (ai)	-944.37^[1]	-870.04^[1]	193.7^[1]	–

* (cr):Crystalline solid, (ai):Ionized aqueous solution

References

List of references

1
Janiel J. Reed (1989)
The NBS Tables of Chemical Thermodynamic Properties: Selected Values for Inorganic and C1 and C2 Organic Substances in SI Units
https://doi.org/10.18434/M32124
National Institute of Standards and Technology (NIST)
Citation list

Δ_rG	−32.0 kJ/mol
K	4.04 × 10⁵
pK	−5.61

Δ_rG	−22.61 kJ/mol
K	9.14 × 10³
pK	−3.96

K2CO3 + CO2 + H2O → 2KHCO3

Reaction data

Chemical equation

General equation

Oxidation state of each atom