Microscale Gas Chemistry:

General Safety Precautions.
    Always wear safety glasses.  Gases in syringes may be under pressure and could spray liquid chemicals.  Follow the instructions and only use the quantities suggested.

Toxicity.
    Nitrogen is relatively non-toxic; however, nitrogen is a simple asphyxiant if inhaled in very large quantities.

Suitability.
    The one experiments described here is ideally suited for use as a laboratory experiment in which all of the data collected by the class are used to determine an important value.

Syringe Lubrication.
    We recommend lubricating the black rubber diaphragm of the plunger with silicone spray (available from hardware stores) or medium-grade silicone oil (Educational Innovations, $5.95 Part #GAS-150; Fisher Catalog Number S159-500; $34/500 mL.)

Equipment. (This equipment can be ordered from a variety of vendors including Educational Innovations, Flinn Scientific (US sales only), Micro Mole, and Fisher Scientific.  Part numbers and links to their websites are provided.)

• 60-mL plastic syringes with a LuerLOK fitting
• Latex LuerLOK syringe cap fittings
• Plastic vial caps that fit within the barrel of the syringe
• Small plastic weighing boat
• Clear plastic beverage cup, 9 oz (260 mL)

 •  0.20 g solid HSO3NH2 (sulfamic acid)
 •  5 mL 0.5 M NaNO2(aq)

     These quantities of reagents will produce approximately 60 mL of N2.  The production of N2 is fast and it typically takes about 15 seconds to fill a syringe with N2.  A trace of reddish NO2 is often observed at first but soon disappears.  The reaction is:

     The N2 gas samples used in these experiments are generated as described in Method A.  Care must be taken to stop the gas generation after the syringe is full.  This is done by removing the latex syringe cap while it is directed upwards.  Rotate the syringe 180^o in order to discharge the reaction mixture and then recap the syringe.
 

Washing the gases.
     The gas-filled syringe must be "washed" in order to remove traces of unwanted chemicals from the inside surfaces of the syringe before the gases can be used in experiments.  To do this, suction 5 mL distilled water into the syringe without discharging any gas, cap the syringe and shake the water to dissolve the contaminants on the inside of the syringe.  Remove the cap and discharge the water but not any of the gas.  Repeat once or twice.

Disposal.
    Unwanted N2(g) samples can be safely discharged into the room.

Experiment 1. Molar volume of Nitrogen.
Equipment:

• Equipment needed to generate nitrogen

• Chemicals needed to generate nitrogen

Figure 1

Figure 2

2. Other Experiments with Nitrogen.
    Nitrogen's lack of reactivity can be demonstrated especially well in conjunction with some of the O2 experiments described in this article.  For example, nitrogen does not support combustion.  Doing a combustion experiment with both O2 and N2-filled syringes will show that N2 does not support combustion.
 
 

  At the end of the experiments, wipe excess lubricant off of rubber diaphragm. Clean all syringe parts (including the diaphragm), caps and tubing with soap and water.  Use plenty of soap to remove oil from the rubber seal.  This extends the life of the plunger.  It may be necessary to use a 3-cm diameter brush to clean the inside of the barrel.  Rinse all parts with distilled water.  Be careful with the small parts because they can easily be lost down the drain. Important: Store plunger out of barrel.