CHE3: NITROGEN AND ITS COMPOUNDS

Ion formation

Nitrogen forms nitride ion by accepting 3 electrons

N + 3 electrons                                    N^3-

2:5                                                       2:8

2 Cu_[s] + O₂ [g]                                    2CuO_[S]

Reddish brown                                               black powder

Solid

The remaining part of air is mainly nitrogen.

It contains rare gases (inert gases) and water vapour as the major impurities

The apparatus is set up as shown in the diagram above. On heating, sodium nitrate reacts ammonium nitrate which decomposes to give nitrogen gas?

Na NO_{2 [aq]} + NH₄CL _[aq]                                              NH₄NO_{2 [aq]} + NaCL_[aq]

NH₄NO_2aq                                                          N₂ + 2H₂O _[L]

The gas is collected over water.

A VIDEO ABOUT ION FORMATION

Other methods for the preparation of nitrogen

The action of chlorine on excess ammonia

3CL_2[g] + 8NH_{3 [g]}                                            N_{2 [g]} + 6NH₄CL_[s]

Passing ammonia gas over heated copper (II) oxide

3NH_{3 [g]} + 3CuONH _[s]                                                3Cu _[s] + N_{2 [g]} 3H2O_[g]

Reduction of oxides of nitrogen by heated copper

2Cu[s] + 2NO[s]                                 2CuO_[s] + 2N_{2 [g]}

Industrial preparation of nitrogen

Tests for nitrogen

Nitrogen is chemically inert. It doesn’t support burning, has no smell. It has no effects on litmus and no effect on the lime water.

It’s slightly less dense than air and is only slightly soluble in water.

Chemical reactions of nitrogen

Under ordinary conditions, nitrogen is chemically inert. Inert nature of nitrogen is due to strong bonding n the nitrogen molecules.

The energy required to break the triple bond is high

In the presence of iron catalyst the moderate temperature (450 – 500⁰C) at high pressure. Nitrogen reacts with hydrogen gas to form ammonia.

N_{2 [g]} + 3N_{2 [g]}                                      2NH_{3 [g]}

Nitrogen reacts with magnesium calcium and lithium metals to form the corresponding metal which appears as white solids.

            3M_g[s] + N_{2 [g]}                                       Mg₃N₂

2Ca_[s] + N_{2 [g]}                                       Ca₃N₂

3Li + N_{2 [g]}                                           Li₃N₂

Uses of nitrogen

1. 3It is a plant nutrient – required in protein synthesis
2. Use in the manufacture of ammonia by Haber process
3. Used as a coolant (refrigerant)