# What is the “smell” of solid sulfur

A solid piece of sulfur has a characteristic smell.

Is the smell of solid sulfur the result of the release of compounds like sulfur dioxide or hydrogen sulfide from a reaction with air or moisture, or is it from elemental sulfur particles that are being released by sublimation?

If it is from pure Sulfur particles (at least in part), what form is it released into the air, ie $\ce{S8}$ or $\ce{S2}$ or something else?

• Sublimation would be a long shot, I doubt it. It can't be S2, since I hear it's pretty unstable and exists only at high temperature ._. The smell is most likely due to the formation of sulfur oxides. – paracetamol Dec 9 '16 at 18:40

The primary candidates for volatilization of odorous sulfur gases are $\ce{SO2}$ and $\ce{H2S}$. Unless the elemental sulfur has been physically ground and dispersed into the air it is not likely the direct source of the smell.

According to the International Volcanic Health Hazard Network, who of course study gaseous volcanic emissions with respect to safety issues:

"Sulfur dioxide ($\ce{SO2}$) is a colourless gas with a characteristic and irritating smell. This odour is perceptible at different levels depending on the individual's sensitivity, but is generally perceived between 0.3-1.4 ppm and is easily noticeable at 3 ppm."

Regarding $\ce{H2S}$, according to the US Occupational Safety and Health Administration (OSHA), $\ce{H2S}$ has a perceptible smell at between 0.01 and 1.5 ppm.

The two gases have different smells, $\ce{H2S}$ being that of rotten eggs and that of $\ce{SO2}$ being described as "pungent and irritating". So that would be one way to differentiate which gas you are smelling.

The most likely candidate is $\ce{SO2}$ as our air is generally oxidizing, and to me elemental sulfur smells more like $\ce{SO2}$ than rotten eggs.

Pure elemental sulfur is completely odorless and tasteless.

The characteristic smell you observed is due to impurities, probably $\ce{H2S}$, sulfur oxides, and organic sulfur compounds, some of which can be perceived in very low concentrations.

• Very true, though if elemental sulfur were aspirated/inhaled it would rapidly react with the moisture present to produce sulfur dioxide, so the "odorless" elemental sulfur would appear to smell like sulfur dioxide. – airhuff Jan 24 '17 at 23:01