Saturated Salt Solutions - Controlling Air Humidity

A salt solutions can be used maintain a particular value of relative humidity.

Saturated salt/water solutions can be used to maintain particular values of relative humidities inside sealed containers. A saturated salt solutions is a slushy mixture based on distilled water and a chemically pure salt.

Saturated salt/water solutions can be used to calibrate humidity sensors. Note that the values below may vary with several percents due to temperature variations, impurities in salt or water or slow saturation.

Saturated Salt Solutions - Controlling Air Humidity
Saturated Salt Solution	Temperature (ºC)
	0	5	10	15	20	25	30	35	40	50	60
	Relative Humidity over the Salt Solution (%)
Ammonium nitrate - NH₄NO³			75	70	67	64	60	53
Ammonium sulphate - (NH₄)₂SO₄	82	82	82	82	81	81	81	80	80	79
Lithium chloride - LiCl ¹⁾					11.31	11.35	11.28	11.25	11.21	11.10	10.95
Magnesium chloride - MgCl₂	34	34	33	33	33	33	32	32	32	31	29
Magnesium nitrate - Mg(NO₃)₂	60	59	57	56	54	53	51	50	48	45
Natrium Cloride - NaCl ¹⁾	75.51	75.65	75.67	75.61	75.47	75.29	75.09	74.87
Potassium sulphate - K₂SO₄	99	98	98	98	98	97	97	97	96	96
Potassium nitrate - KNO₃	96	96	96	95	95	94	92	91	89	85
Potassium chloride - KCl	89	88	87	86	85	84	84	83	82	81	80
Potassium acetate - CH₃CO₂K			23	23	23	23	22
Potassium hydroxide - KOH		14	12	11	9	8	7	7	6	6	5
Sodium chloride - NaCl	76	76	76	76	75	75	75	75	75	74	75
Sodium nitrite - NaNO₂					65	64	63	62	61
Sodium dichromate - Na₂Cr₂O₇	61	59	57	57	55	54	53	51	50	49	47

¹⁾ Saturated aqueous solutions of inorganic salts are convenient for calibration of instruments for measurement of relative humidity

saturated salt solutions and air humidity