MATERIALS REQUIRED
Round bottom flask, delivery tube with cork, water trough, beehive shelf, gas jar, tripod stand with wire gauze, stand with clamp, Bunsen’s burner, sodium nitrite, ammonium chloride.
THEORY
Nitrogen is one of the inactive gases. However, it has a significant role to play in the life of plants and animals. It is also used for industrial purpose. It is found in both free and combined states. It occurs in the free state in air and occupies 78.08% by volume. In combination, it is found in ammonia, saltpeter [potassium nitrate or sodium nitrate (nitre)], etc. It is also found in proteins, enzymes, RNA (ribonucleic acid), DNA (deoxyribo nucleic acid), amino acids and in the products of vegetables and animals.
Nitrogen is prepared in the laboratory by heating a saturated solution of sodium nitrite (NaNO2) and ammonium chloride (NH4Cl).
NaNO2 +NH4Cl ➡ NaCl + 2H2O + N2
PROCEDURE
- Take the solution of sodium nitrite and ammonium chloride in equivalent amount in a round bottom flask.
- Adjust the flask with a delivery tube with the help of a cork and dip the other end of the delivery tube underwater in a trough as shown in the diagram.
- Place a gas jar filled with water over the bee-hive shelf.
- Fit the apparatus airtight and heat the round bottom flask gently with the help of the Bunsen burner.
- On heating the solution of sodium nitrite and ammonium chloride, they react and produce nitrogen gas.
- Collect the nitrogen in the gas jar by the downward displacement of water. The nitrogen obtained from nitrogenous compounds (the sodium nitrite and ammonium chloride) is almost pure which is also called chemical nitrogen.
OBSERVATION
| S.N. | Property | Characteristics |
| 1 | Colour | Colorless |
| 2 | Odor | Odorless |
| 3 | Universal indicator | Neutral (pH-7) |
| 4 | Burning wood inserted into Gas Jar | Extinguished |
| 5 | Burning magnesium ribbon inserted into Gas Jar | Burn Continuously and form yellow ash (Magnesium Nitride) |
RESULT
Nitrogen gas was prepared in laboratory
CONCLUSION
Nitrogen gas can prepared in laboratory by the reaction of Sodium nitrite and ammonium chloride.
PRECAUTION
- Ammonium chloride and sodium nitrite should not be used in their solid forms because ammonium chloride, being a sublimate, sublimes and escapes in the gaseous form on heating.
- The fitted apparatus should be made airtight.
- Heat should be provided uniformly.
- Ammonium chloride and sodium nitrite should be taken in the equivalent amount. 5. The end of the delivery tube in the flask should be high close to the mouth of the flask.
- The bee-hive shelf must be sunk in water.