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14

Typical military-grade thermite mixtures (e.g. used in incendiary hand grenades) contain a large amount of barium nitrate (e.g. 29.0 % in Thermate-TH3, see Patent No. US 6766744). It should be possible to detect the barium oxide that is left over after the fire, maybe first with a simple flame test on site followed by AAS (atomic absorption spectroscopy) in ...


11

Usually the dot is put there to emphasize that the nitric oxide is a free radical that includes an unpaired electron. This is especially notable by comparison with $\ce{NO^+}$, which does not have the unpaired electron. Note that the nomenclature $\ce{·NO}$ should not be rendered as showing the unpaired electron on nitrogen. The unpaired electron is ...


7

According to this Wikipedia article, there has been military research into nano-thermite, which can contain molybdenum, bismuth or tungsten oxides. It would be possible to test for residues of those after the fire. Also, "nano-thermite" sounds awesome!


5

It is not necessary, but optional, to express explicitly the radical status. In other cases, like alkyl radicals, the dot marking is mandatory, not to be confused e.g. with a functional group. For curiosity, the ground state of the oxygen molecule - triplet oxygen - is a biradical, with 2 unpaired electrons. What we write as $\ce{O=O}$ is singlet oxygen, ...


4

Nitric oxide ($\ce{NO}$) is a free radical and hence why that dot is for. Explanation for the dot and the reason why its there have been well answered in other responses. Nevertheless, I decided to put the molecular orbital representation of $\ce{NO}$ as depicted below for your convenience (Ref.1): There are three electrons in antibonding orbitals and ...


3

Your compound has only one proper axis of rotation and it is $C_2$ as shown in the diagram. Therefore, it is the principle axis of rotation. By definition, $\sigma_\mathrm{h}$ is a plane of symmetry perpendicular to the principle axis of rotation. However, the plain you were talking about is paralleled to the principle axis of rotation. Thus, it is not a $\...


3

If a metal is made to react with sulfuric acid, it will form a sulfate salt. When you dissolve those sulfates in water, you would be studying the color of the aquated metal ion. Sulfate is just a counter ion in each case. Search crystal field theory. You are right, iron (II) sulfate in water would be light green, Zn would be colorless, Mn would be light ...


2

Many nuclear power plants use so-called "passive autocatalytic recombiners" for the catalytic oxidization of hydrogen that could be released into the containment in the event of severe accidents. (Note that the affected units of the Fukushima-Daiichi plant did not have such equipment.) The catalytically active materials, typically platinum and/or palladium, ...


2

This is a nice example: the standard reduction potentials are close, so the Nernst equation ultimately reveals what is favored to happen spontaneously, ignoring all real world complications. Consider a galvanic cell having a tin $(\ce{Sn})$ metal electrode in $x~\pu{M}$ aqueous $\ce{Sn(NO3)2}$ and a lead $(\ce{Pb})$ metal electrode in $y~\pu{M}$ aqueous $\...


2

The only well known method to check for (the absence of) chloride ions is precipitation as AgCl (solubility 2 mg/l at 20°C). Mercury(I) chloride is similarly badly soluble, but toxic (and unstable, disproportionation) and therefore bad practice. Lead(II) chloride is already far more soluble (4 g/l) than AgCl, and practically all other simple chlorides are ...


1

Nitrates tend to lower the temperature on dissolving, having a positive enthalpy change of solution. For example, $\ce{NH4NO3}$ has an enthalpy of solution in water of ~26 kJ/mol at ~300 K, and it is used in self-cooling cold-packs for that reason. Sorry, I could not locate the enthalpy change of solution for $\ce{Fe(NO3)3}$, so this is not a definitive ...


1

Another option could be a ion selective electrode (ISE) selective for chlorides, but it would make sense rather for regular checks, as there would be high one time investment. The principle is the same as for the potential reference electrode ... $$\ce{Ag | AgCl | KCl}$$ ... but this time with mono or polycrystallic $\ce{AgCl}$ exposed to the solution. ...


1

The dot represents an unpaired electron. It's written that way as a reduced Lewis dot diagram. The reduction works like this: Start with the typical dot-diagrams for Nitrogen and Oxygen atoms, i.e.$$ \begin{array}{ccc} \textbf{Nitrogen} & \qquad & \textbf{Oxygen} \\[-10px] {\Huge{\begin{array}{rcl} & \cdot \phantom{\cdot} \\[-50px] \...


1

It seems to me that it will be difficult to get a uniform concentration of Zn in a non-uniform material like dried leaves, unless you measure only in bulk (this pile of dried leaves weighs X grams and contains 2000X micrograms of Zn). Things get more confusing if the insects don't eat all the dried-leaf structure (leaving stems, for example). I'm also not ...


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