Making up 78.1% of the Earth's air, by volume, nitrogen is a colorless,
odorless, tasteless gas. From an exhaustible source in our atmosphere,
nitrogen gas can be produced by liquefaction and fractional distillation.
Found in all living systems as part of the makeup of biological compounds,
the purified nitrogen is used in a wide variety of applications
Nitrogen Phosphorus Test Kit
A nitrogen test kit is available in the market for purity testing. This kit
consists of a stick phosphorous which is used instead of copper wire as in
oxygen test kit. Here water is used in place of Ammonium Chloride solution.
White or yellow phosphorous dipped in water is used for absorbing the
oxygen. This forms phosphorous pent oxide, soluble in water. The remaining
volume of gas nitrogen is measured in the burette. Usually, a downward
graduated burette is used which helps in easy reading. As phosphorus is a
combustible element when it is exposed to air, therefore gas consisting of
more than 7% of oxygen should not be passed through the nitrogen test set.
The Process
Once the valve of the test set is opened, the stop-cock is also opened. The
nitrogen gas which is to be tested should be warmed to room temperature for
few minutes. This should continue till the level reaches the zero mark. The
reason behind this is that nitrogen is colder at room temperature and when
it warms up, it should expand. Now the gas flow should be adjusted and the
sample gas should bubble through the purging vessel for few minutes. At the
same time, the burette, the reaction chamber and the test connection tube
should be checked so that they are completely filled with water. Now the
stop-cock should be turned open to the burette connection. Controlling the
nitrogen flow, the other cock should be opened to let the oxygen to pass
into the burette. When the burette is filled below the bottom mark, the stop
- cocks should be closed. Now the nitrogen sample tube is disconnected and
the test valve is closed. The level of the gas in the burette should be
adjusted to the 100 cc mark. This is achieved by holding the leveling bottle
at the water level in the burette. Next you have to open both the cocks
carefully so that the gas bubbles through the purging vessel to atmosphere.
It is now necessary to level the liquid in the burette and the leveling
bottle. The reading indicated on the burette scale at the liquid level
should be carefully noted. This reading is equivalent to purity percentage
of the original Nitrogen sample.
Nitrogen Gas Purity Testing 
