Nitrogen IV Oxide

Submitted by A. Pedler and F. H. Pollard Checked by George Gibson) and Ilmar Kalnin) 

Nitrogen(IV) oxide can be prepared by reducing nitric acid, but it is difficult to obtain a pure product. Pure 

The apparatus is shown in Fig. 9. A 125-ml. dropping funnel A is connected to a 750-ml. round-bottomed dis- 

Two hundred fifty grams of phosphorus(V) oxide (0.88 mol) is placed in flask B and 105 ml. of fuming (95% or more, water-white) nitric acid (2.25 mols) is placed in the dropping funnel. The temperature of the furnace is adjusted to 260° and maintained at this value by means of a suitable Variac.t The nitric acid is then added drop by drop, the addition being sufficiently slow to avoid observed distillation of the acid into the connecting tubes. The reaction is allowed to proceed for 15 to 30 minutes to flush the apparatus completely. Trap H is then surrounded by a Dewar flask containing a mixture of Dry Ice and acetone to condense nitrogen(IV) oxide as a white solid. The reaction is continued until 100 ml. of the acid has been added, and then addition of acid is stopped. 

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Ans. Both compounds have nitrogen in the +4 oxidation state, so if we call N02 nitrogen(IV) oxide, what do we call N204 We actually use the older system for N204—nitrogen tetroxide (or dinitrogen tetroxide). 

Thermal Dissociation of Nitrogen(IV) Oxide. Use two communicating flasks filled with nitrogen(IV) oxide for this experiment (Fig. 46). Immerse flask 1 into a beaker filled with snow or crushed ice, and flask 2 into a beaker with water. Heat the latter and watch the change in the colour of the gas in both flasks. Extract the flasks from the beakers. How does the colour of the gas change ... 

Disconnect U-tube 3 and rapidly pour out the liquid obtained in it into a test tube with cooled water. What do you observe Identify the substance gathering on the bottom of the test tube How can you explain that nitrogen(IV) oxide polymerizes easily ... 

After about 10 cm of solid nitrogen(IV) oxide gathers in receiver... 

Fig. 86. Apparatus for preparing nitrogen(IV) oxide (a) and nitrogen(II) oxide (6)...

Preparation of Anhydrous Copper Nitrate. Prepare 7-10 ml of liquid nitrogen(IV) oxide (see Fig. 86a). If the oxide has solidified,... 

Fig. 92. Preparation of anhydrous copper nitrate a—setup for reacting metallic copper with nitrogen(IV) oxide in ethyl acetate 6—apparatus for distilling off the solvent...

Preparation of Anhydrous Dioxovanadium Nitrate (VO2NO3). Prepare 7-10 ml of liquid nitrogen(IV) oxide (see p. 141). Mix the nitrogen(IV) oxide with 5-7 cm of dry acetonitrile in a test tube (see Fig. 92a). Add 0.3-0.5 g of metallic vanadium preliminarily crushed in a porcelain mortar to this mixture. Close the test tube with a stopper provided with a calcium chloride tube containing phosphoric anhydride. 

Large quantities of nitrogen (IV) oxide are best prepared by allowing 20% sulfuric acid to drop slowly into 40% sodium nitrite solution contained in an evolution flask and treating the evolved gas mixture as previously described. 

Above 1S0°C nitrogen (IV) oxide slowly decomposes to trogen (II) oxide and oxygen ... 

Material prepared in this manner has retained a bright orange color for over one year of storage without access of air. The stability of the product appears to depend on the washing of the crystals on the filter. Potassium peroxyl-amine disulfonate is dimeric in the solid state but is dissociated into the monomeric form in solution. In this, it bears a close structural relationship to nitrogen (IV) oxide. 

The complexes [Fe(NO)(S2CNMe2)2] (60), Fig. 8, and [Fe(NO)-(S2CNEt2)2] (61) both have square-pyramidal geometry with a linear, apical, Fe-N-0 group. The nitrogen(IV) oxide oxidation product... 

Platinum Pt oxygen and nitrogen(iv) oxide nitrate oxide ... 

Nitrogen(iv) oxide (N02) Brown (very choking smell) Pink-weakly acidic Brown colour Turns moist indicator paper pink... 

Nitrogen (IV) oxide, 6 87 Nitrogen (V) oxide, 3 78 Nitrogen selenide, as explosive product in reduction of strontium selenite with ammonia, 3 21 N itropentamminechromium (III) nitrate, 5 133... 

Nitric acid, UNO 3, and the nitrates are familiar enough so that little space need he devoted to them. It will be recalled that the acid is an excellent oxidizing agent when hot and concentrated, dissolving many metals and metallic sulfides, the latter with the formation of sulfur or sulfate. The reduction products of nitrate in acid solution are almost always the nitrogen(II) or nitrogen(IV) oxides, but nitrate can be reduced to ammonia in basic solutions, using active metals (such as zinc or aluminum). 

The dried oxygen is introduced into the ozone source under a pressure of 8 p.s.i. (415 mm. Hg) and with a voltage of 110 5 volts applied to the ozone instrument. The flow valve indicating the rate of flow for ozone is set at 0.1 standard cubic feet per minute (2.8 l./minute). The nitrogen-(IV) oxide is taken from the tank as a slow gas stream by... 

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