Chemistry - Does an electrically conductive gas exist at room conditions?

Solution 1:

It depends on what you are prepared to consider a gas and what you are prepared to consider room conditions.

The gas inside all discharge lamps (fluorescent lamps and neon lamps in shop signs, for example) conducts electricity and the lamps work under normal room conditions. However, the gases are often at low pressure and are, strictly speaking, plasmas not room temperature neutral gases. Some lamps, especially high intensity ones like the xenon discharge lamps in floodlights) exist with high pressure gas when working so low pressure isn't the key.

And air itself will conduct electricity given the right conditions. Lightning couldn't exist if it didn't. Nor could you get the (much safer) discharges from Tesla Coils or Van de Graaff generators. But, again, the effect relies on the creation of a plasma from the breakdown of the neutral molecules in the gas.

So the answer is "yes" but only if you allow plasmas created from the medium to count as a normal gas.

Solution 2:

Air at STP does conduct a tiny bit due to ionization by cosmic rays; this might even provide a path for lightning leaders. "Alex V. Gurevich of the Lebedev Physical Institute [et al] suggest that... cosmic ray... might provide a conductive path that initiates lightning."

In addition, ionization-type smoke detectors use a little radioactive material (e.g. $\ce{^241Am}$) to increase conductivity, which can be detected with a high-impedance amplifier.

Solution 3:

The gas inside discharge neon lamp is not really hot. Also, think of St. Elmo's fires - these definitely do appear at ambient pressure and are "cold", i.e., normally they would not burn anything. But there is a catch: here we are looking at strongly non-equilibrium situations, caused by strong electric fields.

As for the gases which would behave like that in normal conditions, I haven't heard of such. Some compounds turn into plasma easier than others, but still that requires many hundreds °C. Among the easiest are complex halogenides like $\ce{KBF}_4$ or $\ce{KAlCl}_4$. At 1000K they may be not vaporized yet, but have some vapor pressure. Also, it's not like the vapors consist entirely of ions - no, far from that, the ions are still a minority, but that's enough to create some significant conductivity.