[throwaway2048]

Another problem with silicon is that its basic oxide (Silicon Dioxide) is a solid that is non-reactive with virtually everything.

If you assume water based life, there is almost certainly going to be oxides involved, such as how CO2 is involved with earth life.

And I think water based life chemistry is an extremely good bet, because alternative liquids based off of light, common elements are either only liquid at very low temps, (ammonia, methane) extremely reactive ( Hydrogen fluoride, hydrogen sulfide), or both.

Another consideration with silicon is that the earth contains vastly more silicon than it does carbon (in many ways life on earth is fairly carbon starved), yet life based on carbon arose, not silicon.

[thaumasiotes]

> Another problem with silicon is that its basic oxide (Silicon Dioxide) is a solid that is non-reactive with virtually everything.

I was amused once by reading an MSDS for silicon dioxide.

As I presume is required, they do list some hazards of exposure, but if you read the sheets for other substances the contrast is pretty striking. Look at the health effects listed on https://fscimage.fishersci.com/msds/09890.htm :

> Eye: Dust may cause mechanical irritation.

> Skin: Dust may cause mechanical irritation.

> Ingestion: May cause irritation of the digestive tract.

> Inhalation: Dust is irritating to the respiratory tract.

> Chronic: May cause cancer in humans. Prolonged exposure to respirable crystalline quartz may cause delayed lung injury/fibrosis (silicosis).

> NFPA Rating: (estimated) Health: 1; Flammability: 0; Instability: 0

So yeah, as long as you're not inhaling sand, you're fine.

[erik_seaberg]

I'm reminded of

> [Chlorine trifluoride is] also a stronger oxidizing agent than oxygen itself, which also puts it into rare territory. That means that it can potentially go on to “burn” things that you would normally consider already burnt to hell and gone, and a practical consequence of that is that it’ll start roaring reactions with things like bricks and asbestos tile. It’s been used in the semiconductor industry to clean oxides off of surfaces, at which activity it no doubt excels.

—Derek Lowe, “Sand Won’t Save You This Time”

[thaumasiotes]

And from an MSDS for that...

> Hazardous combustion products: None that are more toxic than the product itself.

( https://www.boconline.ie/en/images/chlorine_trifluoride_tcm6... )

It's a fun read.

[erik_seaberg]

Material Safety: None. The End.

> Contains no other components or impurities which will influence the classification of the product.

In the unlikely event you survive adding something, you won’t make it any better. You certainly can’t make it worse.

> Unsuitable extinguishing media: Water, Foam, Halons

> Specific methods: Move away from the container and cool with water from a protected position.

Um.

> May react violently with combustible materials.

Specifically, everything.

> Seek medical advice before using product.

“Don’t.”

> Ensure vehicle driver is aware of the potential hazards of the load

Driving is a strong indication that he is not aware.

> and knows what to do in the event of an accident or an emergency.

“Run.”

[zaarn]

Similar fun would likely be the safety sheet for FOOF (Dioxygen diflouride), a compound that you can't really get to room temperature without said compound tearing itself and it's container apart. I do recall it reacts "vigourosly" (I believe the paper I read on this used those specific words) with Chlorine triflouride at 90K (-180C, -300F).

[erik_seaberg]

> The sulfur chemistry of FOOF remains unexplored, so if you feel like whipping up a batch of Satan’s kimchi, go right ahead.

—also Lowe

[thaumasiotes]

To be fair, most stuff involving fluorine is like this. Compare https://fscimage.fishersci.com/msds/11171.htm (for extra chlorine trifluoride fun, this is one of the things you get if you react it with... water. Hence the entry in "unsuitable extinguishing media".):

> Danger! May be fatal if inhaled, absorbed through the skin or swallowed. Both liquid and vapor can cause severe burns to all parts of the body. Specialized medical treatment is required for any exposure... can cause metabolic imbalances with irregular heartbeat, nausea, dizziness, vomiting and seizures. Long-term exposure may cause bone and joint changes. Will attack glass and any silicon-containing material. Corrosive to metal.

> Potential Health Effects

> Eye: Contact with liquid or vapor causes severe burns and possible irreversible eye damage.

> Skin: May be fatal if absorbed through the skin. Causes severe burns with delayed tissue destruction. Substance is rapidly absorbed through the skin. Penetration may continue for several days. Causes severe tissue necrosis and bone destruction.

> Ingestion: Causes severe digestive tract burns with abdominal pain, vomiting, and possible death.

> First Aid Measures

> Eyes: Do NOT allow victim to rub eyes or keep eyes closed. SPEEDY ACTION IS CRITICAL! GET MEDICAL ATTENTION IMMEDIATELY!

> Skin: Discard contaminated clothing in a manner which limits further exposure. Destroy contaminated shoes. Spills should be flushed until medical attention arrives. SPEEDY ACTION IS CRITICAL! GET MEDICAL ATTENTION IMMEDIATELY.

> Ingestion: Get medical aid immediately. SPEED IS ESSENTIAL. A DOCTOR MUST BE NOTIFIED AT ONCE.

> Inhalation: SPEED IS ESSENTIAL, OBTAIN MEDICAL AID IMMEDIATELY. POISON material. If inhaled, get medical aid immediately.

(ALL CAPS are original to the MSDS.)

> Wear chemical splash goggles and face shield.

> Wear butyl rubber gloves, apron, and/or clothing.

> Wear appropriate protective clothing to prevent skin exposure.

> Wear a NIOSH/MSHA or European Standard EN 149 approved full-facepiece airline respirator in the positive pressure mode with emergency escape provisions.

> Never work alone with this chemical.

> Substance is noncombustible

[zaarn]

The statement that it produces no chemicals more toxic than itself is true but misleading because the combustion products will largely consist of chlorine gas, hydroflouric gas (not the acid, the gas) and a variety of other flourine compounds waiting to make your internal metabolism incompatible with life.

I would also argue that CO2 and dry powder isn't an suitable extinguishing media for this, as CF3 doesn't give much of a shit when it's got it's own hyperactive oxidizer on board.

[raverbashing]

SiO2's "toxicity" is more mechanical than chemical (it's coarse and rough, etc)

But it's pretty much inert chemically (for human levels of chemical reactions)

[Simon_says]

Sure. It's just sand, and it gets everywhere.

[int_19h]

> common elements are either only liquid at very low temps, (ammonia, methane)

But they are very low temps on our scale, which is centered around water.. There are many places, even in our own solar system, where these are liquid all the time, and water is solid all the time.

[throwaway2048]

Sure but the problem is that chemical reactions are MUCH slower at such low temps, perhaps much too slow for life to exist.