Gaseous N[sub]2[/sub] is very inert due to the triple bond and absence of bond polarity (its symmetry).
Getting the N out of nitrogen gas is not easy. It is done in nature with nitrogen fixation in legumes and lightening discharges, but has been a problem for chemists. At the beginning of last century we worked out how to react nitrogen gas with hydrogen to form ammonia (Haber high pressure catalytic reduction of the nitrogen).
Once you have nitrogen in the more reactive ammonia, you are opened up to creating a whole range of other nitrogen containing compounds. In this way nitrous oxide can be produced from the ammonia.
As with many chemical synthesis, you need to take a number of steps to get to the final product. Nitrous can be made from the thermal decomposition of molten ammonium nitrate. It can also be made from the reduction of aqueous nitrous acid with hydrogen azide (HN[sub]3[/sub]) or hydroxylamine (NH[sub]2[/sub]OH). Of course there are other ways too.
Lets stick with the hydrazine route. Hydrazine can be prepared by the reaction of ammonia with sodium hypochlorite (bleach). Hydrazine is very toxic - why you dont mix houshold bleach with other cleaners.
So, you start with nitrogen gas --> ammonia --> hydrazine --> nitrous oxide
Oh I didnt tell you how to make nitrous acid. Basically by reacting your ammonia with oxygen and water. Also the route to fertilisers and explosives.
The energy does indeed come from photosynthesis in those bacteria associated with roots. The energy comes in the form of sugars produced via phs in the leaves of the host plant and pumped down to the roots. The bacteria are fed these sugars and they use that energy to fix nitrogen.\
Many other bacteria including the clostridia responsible for tetanus and botulism and the cyanobacteria can also fix nitrogen by themselves. The clostridia just rely on whatever substrate they are digesting normally while the cyanobacteria are photosynthetic in their own right.
The bacteria may not need as much energy to fix the nitrogen into ammonia. Unlike nitrogen fixation that happens during lightning, the bacteria might use enzymes in their body as catalysts. This effectively reduce the activation energy required for combining nitrogen with other elements. Both reactions in the bacteria as well as in the lightning will still give the same net result of energy transfer (exothermic I assume). It is just that one will require less activation energy than the other.
No one knows the exact mechanism of how bacteria such as rhizobium fix nitrogen.
An enzyme called ‘nitrogenase’ has been isolated from a range of bacteria such as mentioned by Blake. It probably contains a molybdenum-iron complex that the nitrogen coordinates to, weakening the triple bond and making it susceptible to reduction by the enzyme.
If someone can work out how to fix nitrogen at room temp. and pressure they would be very popular.
So Priceguy if you are writing a fictional story, you could say that someone develops a coordination compound that binds nitrogen gas, and through various subtle and ingenious modes too complicated to mention here, reacts the nitrogen with oxygen in the air at STP to form nitrous oxide. And a spoonful of this compound, which is unaffected by the reaction, dispersed in the air fills a room with a intoxicating concentration of nitrous within minutes.
How exothermic (or not) would this theoretical reaction be, though? Would it be capable of raising or lowering the room temperature significantly?? Just curious.
Speaking of fictional stories, and this is something of a leap away from nitrogen reactions, I remember something I came up with for a story about life capable of surviving on Venus. Obviously they’d need to have cellular structures very different from earth creatures to survive in the venusian environment, but the part that I really liked was how the ecosystem would most commonly derive energy from the environment.
Since there are such thick clouds on Venus, I thought that deriving energy directly from sunlight wouldn’t be practicable (except maybe if some form of life could float above all the clouds, but I didn’t go that way.) Instead, I theorized that the fundamental life forms were capable of absorbing complicated sulfur compounds that develop naturally in the heat and pressure of the venusian environment, and through enzymes and special structures used to decrease internal pressure, break down those compounds to release energy. When the waste products of that reaction are flushed back into the venusian atomosphere, they spontaneously revert back into the original compounds in an endothermic reaction, absorbing a very tiny amount of the raging heat in so doing.
It’s not a million miles away from one of the possible mechanisms suspected of sustaining the hydrothermal vent bacteria in the absence of any direct photosynthesis.
Incidentally, the stability of the N[sub]2[/sub] molecule is closely related to why so many explosives contain nitrogen. To put it simply, nitrogen “likes” to be bonded with another nitrogen, and if it’s in any other form, it’s eager to recombine in such a way to form N[sub]2[/sub].
And chrisk, it sounds to me like your proposed Venusian metabolism would run afoul of the Second Law of Thermodynamics. Presumably, the Venusian climate is pretty well thermally equalized (everything at the same temperature), which would make it impossible to extract any useful energy from the heat of the environment.
