Nitrous oxide notes’

The decomposition of nitrous oxide (NjO) to nitrogen and oxygen is preformed in a 5.0 1 batch reactor at a constant temperature of 1,015 K, beginning with pure NjO at several initial pressures. The reactor pressure P(t) is monitored, and the times (tj/2) required to achieve 50% conversion of N2O are noted in Table 3-19. Use these results to verify that the N2O decomposition reaction is second order and determine the value of k at T = 1,015 K. 

As far as flame composition is concerned, it may be noted that an acetylene-air mixture is suitable for the determination of some 30 metals, but a propane-air flame is to be preferred for metals which are easily converted into an atomic vapour state. For metals such as aluminium and titanium which form refractory oxides, the higher temperature of the acetylene-nitrous oxide flame is essential, and the sensitivity is found to be enhanced if the flame is fuel-rich. 

Key L = fuel-lean R = fuel-rich AA= air/acetylene AP = air/ propane NA= nitrous oxide/acetylene AH = air/hydrogen Notes (1) If there are many interferences then NA is to be preferred. 

Linus Pauling, Proc. Nat. Acad. Set., 18, 293 (1932). Examples of molecules which resonate among several Lewis structures are given in this paper. Further discussion of the nitrous oxide molecule is given in a later note, Linus Pauling, ibid., July, 1932. 

Much interest is noted in the development of catalysts that decompose nitrous oxide into its elements, at rates and conditions that are compatible with the production sources. 

For the alkaline-earth metals, as noted earlier, a simple flame of almost any type can be used to excite the metals. However, to be able to determine a wide range of metals, it is common to use either an acetylene-air or acetylene-nitrous oxide flame as the source of energy to excite the atoms. The burner is long with a slot at the top and produces a long narrow flame that is situated end-on to the optics receiving the emitted light. 

In a recent note I applied a table of atomic radii for use in covalent molecules in predicting values of the moment of inertia of nitrous oxide, asstuning various structures for the normal state. The values given are the following ... 

Contrast-enhanced MRI with Gd-DTPA has been applied to the evaluation of several compounds in man, some focusing on the hemodynamic effects of the drugs on cerebral blood volumes. Kolbtisch and others compared the anesthetic agents nitrous oxide and sevofhirane, noting them to produce compound-specific patterns of diffuse increases in cerebral blood volume (Kolbitsch et al., 2001). Intravenous cocaine, on the other hand, was observed to produce dose-dependent vasoconstriction of cerebral blood vessels (Kaufman et ul., 1998). 

In a 1.5-1. beaker (Note 1), 191 ml. (180 g.) of aqueous 25% dimethylamine solution (1.0 mole) is diluted with 64 ml. of water and treated with 116 g. (1.1 moles) of nitrourea.2 The temperature of the resulting brownish liquid rises spontaneously to 35-42°. The solution is warmed to 56-60°, and a reaction sets in vigorously with evolution of nitrous oxide. External cooling with water is applied when required the reaction temperature is maintained below 70° during the first 5-7 minutes and below 85° during the second period of 5-7 minutes. After a total of 10-15 minutes, the effervescence slackens and the reaction mixture is kept at 90-100° until the evolution of gas has completely ceased. This usually requires an additional 15-20 minutes. 

Nitrous oxide (N2O, see Section 2.11) is a colorless, odorless gas with mildly anaesthetic properties (laughing gas). It is formed in Nature by bacterial reduction of nitrates. The electronic structure of this linear molecule is best understood by noting that it is isoelectronic with CO2, which is also linear. It is rather easily decomposed into N2 and 02, and so can support combustion. 

Nitrous oxide is nontoxic—it used as the propellant in whipped-cream spray cans—and so might seem to be an unlikely pollutant. However, as noted earlier, it may contribute significantly to greenhouse warming. Furthermore, on diffusing to the stratosphere, N20 becomes involved in the ozone cycle (reactions 8.2, 8.3, and 8.6) following its conversion to nitric oxide (NO) ... 

---