Gas purification techniques

Solubility in water

Temperature affects both the equilibrium position of the precipitation reaction and the reaction rate. In general, solubility increases with the increasing temperature with a few notable exceptions such as CaCO₃, Ca₃(PO₄)₂, CaSO₄ and FePO₄ which are of importance in the water chemistry. To calculate the solubility at a temperature with the equation:

and with the van't Hoffs equation you can calculate the difference in solubility:

Where:
K₁= Solubility of substance with highest temperature
K₂= Solubility of substance with lowest temperature
H = Enthalpy
G = Gibbs energy
R = Ideal gas constant
T₁= Temperature of substance with highest temperature
T₂= Temperature of substance with lowest temperature

Below you will see a table and the solubility of the chemical substances and you will notice that with most of the chemical substances the solubility rises with the temperature.

Name of chemical substance		Solubility (g/l)	Temperature (^oC)
Aluminum chloride	AlCl₃ . 6 H₂O	456	20
		477	80
Aluminum hydroxide	Al₂(OH)₃	0.0015	20
Aluminum sulfate	Al₂(SO₄)₃ . 18 H₂O	363	20
		730	80
Ammonia	NH₃	520	20
		310	40
		200	60
Ammoniumdihydrogenphosphate	(NH₄)H₂PO₄	368	20
		1207	80
Ammonium sulfate	(NH₄)₂SO₄	754	20
		941	80
Barium carbonate	BaSO₄	0.035	30
Barium hydroxide	Ba(OH)₂ . 8 H₂O	34.8	20
		908	40
Barium sulfate	BaSO₄	0.0023	20
		0.0039	80
Calcium chloride	CaCl₂ . 6 H₂O	745	20
		1470	80
Calcium carbonate	CaCO₃	0.015	20
		0.035	80
Calcium hydroxide	Ca(OH)₂	1.67	20
		0.66	80
Calcium sulfate	CaSO₄ . 2 H₂O	2.04	20
		1.8	80
Chloride	Cl₂	7.3	20
		4.5	40
		3.3	60
		2.2	80
Hydrogen chloride	HCl	721	20
		633	40
		561	60
Diammoniumhydrogenphosphate	(NH₄)₂HPO₄	686	20
		1155	80
Disodiumhydrogenphosphate	Na₂HPO₄. H₂O	766	20
		924	80
Iron bicarbonate	Fe(HCO₃)₂	0.77	18
Iron(III)chloride	FeCl₃ . 6 H₂O	919	20
		5251	80
Iron(II)hydroxide	Fe(OH)₂	0.00142	20
Iron(III)hydroxide	Fe(OH)₃	4.8 x 10^-8	18
Iron(II)sulfate	FeSO₄ . 7 H₂O	266	20
		438	80
Potassium permanganate	KMnO4	63.8	20
		250	65
Carbon dioxide	CO₂	1.688	20
		0.973	40
Copper sulfate	CuSO₄ . 5 H₂O	0.576	60
		209	20
Magnesium carbonate	MgCO₃	536	80
		0.084	20
Magnesium chloride	MgCl₂ . 6 H₂O	0.06	100
		542.5	20
Magnesium hydroxide	Mg(OH)₂	658.7	80
Magnesium sulfate	MgSO₄ . 7 H₂O	0.009	18
		356	20
Manganese bicarbonate	Mn(HCO₃)₂	540	80
		0.8	20
Manganese(II)hydroxide	Mn(HCO₃)₂	0.05	20
Manganese(IV)hydroxide	Mn(OH)₂	0.00043	20
Manganese sulfate	MnSO₄ . 5 H₂O	629	20
		455	80
Sodium bicarbonate	NaCO₃	95.7	20
		197	80
Sodium carbonate (soda)	Na₂CO₃ . 10 H₂O	215.8	20
		445	80
Sodium chloride	NaCl	358.5	20
		380.5	80
Sodiumdihydrogenphosphate	NaH₂PO₄ . 2 H₂O	852	20
		2073	80
Sodium fluoride	NaF	41	20
Sodium hydroxide	NaOH	1070	20
		3137	80
Sodium sulfate	NaSO₄ . 10 H₂O	190.8	20
		430.9	80
Sodium sulfite	Na₂SO₃ . 7 H₂O	266	20
		290	80
Sulfur dioxide	SO₂	106.4	20
		55.4	40
		32.5	60
		21.3	80
Nitrogen	N₂	0.019	20
		0.0139	40
		0.0105	60
		0.0066	80
Trisodiumphosphate	Na₃PO₄ . 12 H₂O	132	20

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