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Solubility of Nitrogen






There are three ways of expressing the relationship of solubility by volume between gases and liquids.
  1. Absorption coefficient β (Bunsen) is the volume of gas, reduced to N.T.P., which is absorbed by unit volume of liquid, when the pressure of the gas is 760 mm. without the vapour tension of the liquid.
  2. Solubility β' is the volume of gas, reduced to N.T.P., which is absorbed by unit volume of liquid, when the total pressure is 760 mm. (i.e. including the vapour tension of the liquid),

    β' = β(760-f)/760,
    where f=vapour tension of liquid at the temperature of the experiment.
  3. Solubility coefficient l (Ostwald) is the volume of gas dissolved by unit volume of liquid at the temperature and pressure of the experiment. It is not reduced to N.T.P. Hence, if the measurements are made at atmospheric pressure,

    l=β(1+0.00367t).
The following table gives the solubility of nitrogen in water in terms of the absorption coefficient β:

Solubility of nitrogen in water

Temp.° C.Atmospheric Nitrogen.Argon-free Nitrogen.
WinklerFoxWinklerFox
00.023540.023590.02312 0.02319
100.018610.018950.018290.01863
200.015450.015980.015180.01572
300.013420.013980.013190.01375
400.011840.012520.011640.01233
500.010880.011330.010710.01160


The formula deduced by Fox for the solubility of pure nitrogen is

1000β=22.998-0.5298t+0.009196t2-0.00006779t3,

which is obtained by allowing for 1.185 per cent, argon.

The Rate of Solution of Nitrogen in Water. - Adeney and his collaborators have investigated the rates of absorption of nitrogen, oxygen, and air by water under gentle agitation. The results are summarised by the formula


where
w=initial percentage saturation capacity for nitrogen.
w1=amount dissolved after a given time θ.
e=Napierian logarithmic base.
F=0.0103 (T - 240).
A=area of water exposed to the gas.
V=volume of water.

As in the case of oxygen, the solubility of nitrogen in sea-water decreases with increasing chlorine content. The calculated formula expressing these results is:

1000β=18.639-0.4304t+0.007453t2-0.0000549t2-Cl(0.2172-0.007187t+00000952t2),
the chlorine being expressed as grams per litre.

Solubility of nitrogen containing argon in sea-water from a free, dry atmosphere at 760 mm

Parts of Chlorine per 1000.Temperature, ° C.
048121620
018.6417.0215.6314.4513.4512.59
417.7416.2714.9813.8812.9412.15
816.9015.5114.3213.3012.4411.70
1216.0314.7513.6612.7211.9311.25
1615.1814.0013.0012.1511.7310.81
2014.3113.2712.3411.5710.9210.36


The solubility of nitrogen in aqueous solutions of barium and sodium chlorides is as follows:

Solubility of nitrogen in aqueous salt solutions

Temperature, °C.Coefficient of Absorption in Barium Chloride Solutions.
13.83 per cent.11.92 per cent.6.9 per cent.3.87 per cent.3.33 per cent.
50.01270.01370.01600.01800.0183
100.01170.01250.01470.01660.0168
150.01040.01140.01320.01480.0150
200.00920.00980.01180.01320.0135
250.00780.00860.01040.01140.0119
Coefficient of Absorption in Sodium Chloride Solutions.
11.73 per cent.8.14 per cent.6.4 per cent.2.12 per cent.0.67 per cent.
50.01020.01270.01380.01790.0200
100.00930.01130.01260.01640.0185
150.00810.01010.01130.01470.0164
200.00660.00870.00980.01310.0148
250.00470.00750.00830.01130.0130


The following table gives the solubility of nitrogen in ethyl alcohol at various temperatures:

Solubility of nitrogen in alcohol

Temperature, ° C.0510152024
Absorption coefficient0.12630.12440.12280.12140.12040.1198


The solubility of nitrogen in mixtures of ethyl alcohol and water is given by Just.

Solubility of nitrogen in aqueous ethyl alcohol

Per cent. Alcohol.0203399.8
Solubility product l250.016340.015360.017190.1432


Critical temperature: from -146 to -144.7
Critical pressure: from 32 to 35
Critical density: from 0.31096 to 0.32690

The solubility of nitrogen in natural petroleum is of the same order as that in alcohol; the absorption coefficient at 10° C. is 0.135 and at 20° C. is 0.117.

Nitrogen is much less soluble in aqueous solutions of glycerol and in aqueous solutions of sugars than in water.


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