What's special about molecules with molybdenum?

[sbergman27]

Sodium is a soft metal that reacts violently with water. Chlorine is a poisonous gas. Sodium Chloride is a salt, which has completely different properties than either sodium or chlorine. It resembles them not at all in texture. Nor in physical or chemical properties.

Oxygen is a gas. Hydrogen is a gas. Put them together and ignite the mixture... and you get H2O: Water. A very different substance from, say, hydrogen chloride (hydrochloric acid) or iron oxide (common rust).

Mercury, despite widespread public fear, is pretty harmless in its pure, metallic form. But molecules of methyl mercury, found in certain fish, are quite toxic.

So why do we speak of "moly" being a good anti-wear additive? The old molybdenum-disulfide was good at protecting, but had some problems. But the "new" moly, organic moly, has the advantages of moly without the problems.

If I were to say that table salt has all the advantages of sodium, without the problems, people would think I was crazy. So why do we say essentially the same thing about disparate molecules which happen to contain the element molybdenum?

Just wondering...

 

[Henry964]

Please let me know the problems with the use of MOS2 (I am a user of Lubro Moly oils and products)

 

[[RT] ProjUltraZ]

mercury is extremely dangerous because it volatilizes at room temp and you can breathe it in, absorbing it and it builds up too

 

[sbergman27]

Originally Posted By: ProjUltraZ
mercury is extremely dangerous because it volatilizes at room temp and you can breathe it in, absorbing it and it builds up too

Mercury melts from a solid to a liquid at -38F. It boils at 674F. Volatizes? At room temperature it is practically frozen. Its vapor pressure is about 0.00015 PSI on a *really* hot summer day.

I remember, back in the 60s, my dad and I made a mercury barometer. That involves having an open cup of mercury at the base of an evacuated tube. Years later the cup was still as full as the day we originally filled it. (No yearly top-ups.)

Of course, we also had a fireplace with gas-logs sitting on a bed of shredded asbestos. (Asbestos glows nicely, simulating embers.) A few years later companies were making millions sending technicians into schools in space suits to remove the deadly substance.

Dad lived to 87. I'm 47. And no member of our family has developed lung cancer, died of heavy metal poisoning, or given birth to any 3 headed monsters.

Be careful about believing hype. Can you point me to any verified instances of elemental mercury causing sickness or death under normal conditions? Or is this just something you've heard.

 

[oblivion]

I think both mercury and asbestos are fine... as long as you don't breathe or otherwise ingest them. Like grinding tile with asbestos and breathing the dust, or mercury compounds leaching into the groundwater. As long as you use them and dispose of them properly, no real danger.

But people are idiots and don't bother to learn these things. I truly think since people don't have to work as hard to survive and use common sense daily as they did even 60 years ago, that people are just getting dumber every day. Natural selection just isn't weeding out the incompetents like it used to.

 

[znode]

Originally Posted By: sbergman27

If I were to say that table salt has all the advantages of sodium, without the problems, people would think I was crazy. So why do we say essentially the same thing about disparate molecules which happen to contain the element molybdenum?

Just wondering...



Uh, didn't you just answer your own question? Chemistry is unpredictable, especially when you cross into organic chemistry and its all-covalent properties.

What exactly is your concern? The claim that organic moly is different from MoS2? Or that the claim that organic moly "has no downsides"?

The first is pretty obvious. The second, you should obviously see as marketing. There is no such thing as "no downsides".

 

[GMorg]

The reason why the term "moly" is thrown around as though all sources of molybdenum are interchangeable is because it is being misused by people who don't understand what they are talking about. The OP is right on point. Different "moly" compounds are very different from one another. Using MoS2 to get the benefits of molybdenum dithiophosphate or molybdenum dithiocarbamate isn't that different from thinking that galvanized nails in your oil pan is a nice supplement to keep cams protected. The nails may keep the zinc levels up if the TBN gets low, but they will never be a source of Zinc dithiophosphate.

 

[JAG]

Well, molybdenum dithiocarbamate actually reacts to form MoS2 in sufficiently severe rubbing scenarios. It is the molecular structure of MoS2 that gives it very low shear strength that is so desirable. This is mentioned in a lot of scientific papers if you want to look into it.

 

[[RT] ProjUltraZ]

not to sidetrack, but your mercury numbers are off http://www.scorecard.org/chemical-profiles/html/mercury.html
https://fpm-www3.fpm.wisc.edu/safety/occupationalHealth/Topics/Mercury/tabid/148/Default.aspx

 

[sbergman27]

Originally Posted By: [RT
ProjUltraZ] not to sidetrack, but your mercury numbers are off

In what way are the numbers off?

And yes, I'm aware of the alarmist "how to clean up" web pages out there.

 

[znode]

Originally Posted By: sbergman27

Dad lived to 87. I'm 47. And no member of our family has developed lung cancer, died of heavy metal poisoning, or given birth to any 3 headed monsters.

Be careful about believing hype. Can you point me to any verified instances of elemental mercury causing sickness or death under normal conditions? Or is this just something you've heard.

Ok now that's going a bit too far. I agree the public perception of "oh no I broke a thermometer/bulb/ate a tuna we're all going to die" is horribly overblown. But to imply that elementary Hg has never caused sickness, and then quote anecdotal evidence about your family, would be going overboard in the other direction. Uncomfortably into the "EPA is all just a conspiracy there are no unsafe chemicals man up nobody ever died in mah generation" territory.

There's quite a few controlled studies on chronic elemental Hg exposure, with demonstrable evidence of neurological deterioration. For example http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1039326/

Originally Posted By: [RT
ProjUltraZ] not to sidetrack, but your mercury numbers are off http://www.scorecard.org/chemical-profiles/html/mercury.html
https://fpm-www3.fpm.wisc.edu/safety/occupationalHealth/Topics/Mercury/tabid/148/Default.aspx


They're not off... he's quoting Fahrenheit?

 

[sbergman27]

Originally Posted By: znode
Ok now that's going a bit too far. I agree the public perception of "oh no I broke a thermometer/bulb/ate a tuna we're all going to die" is horribly overblown. But to imply that elementary Hg has never caused sickness...
...

There's quite a few controlled studies on chronic elemental Hg exposure, with demonstrable evidence

I think you missed the part where I said "normal conditions". I would not consider chronic exposure to be normal conditions. Nor would I consider mercury sitting in a beaker in the corner to be chronic exposure.

 

[[RT] ProjUltraZ]

Originally Posted By: sbergman27
Volatizes? At room temperature it is practically frozen. Its vapor pressure is about 0.00015 PSI on a *really* hot summer day.


mercury vapor pressure is .002 mm Hg at 75 F your bp and fp are correct but why would you say it's frozen at room temp? it melts at -38 F

ok a broken thermo won't kill you, but why add to mercury build up in your body, unless you never eat any seafood, then you might have less. but i don't consider this quote alarmist

"Mercury spilled on the floor in a room will not result in equilibrium vapor pressure in any reasonable amount of time. Undisturbed evaporation of a 10 cm diameter pool of mercury is estimated at 0.1 mg/sec, which gives very low levels of vapor in lab air."

that's 1 gram every 2 hours 45 min volatilized at room temp or 1 oz every 77 hours. it will disappear unless air tight

 

[sbergman27]

Originally Posted By: ProjUltraZ
mercury vapor pressure is .002 mm Hg at 75 F your bp and fp are correct but why would you say it's frozen at room temp? it melts at -38 F

I didn't. I said that it's "practically frozen" at room temperature. Meaning near enough its freezing point, relative to its boiling point, that one would not expect much of a vapor pressure. (And then quoted the vapor pressure, confirming that there is not much at even warm temperatures.)

My figure for VP is 1 pascal at 315K, which I converted to 0.00015 psi. This actually works out to 0.0075 mm Hg at 42C or 108F. You are quoting at 0.002 mm Hg at 75F, so I'd say the numbers look reasonably compatible. (If we continue this we should really settle on one system of units. I'll take the blame for starting off with US Customary Units. I didn't think we were going to get quite so nitty-gritty. I vote SI.)

Quote:
ok a broken thermo won't kill you,

No. It won't.

Quote:
but i don't consider this quote alarmist

I consider its accuracy to be quite dubious.

0.1 mg/sec works out to 3.3kg per year. Or more to the point... wouldn't you be just a *little* surprised if you left a 10cm circular, 3mm thick, pool of mercury on a table at room temperature and came back less than 2 hours later and it had all evaporated away? Because that's what your quoted text implies. Do the math. And if that doesn't seem really questionable to you, you haven't actually had much observational experience with mercury. No one ever had to refill their mercury barometers. We didn't "top up" our barometers. Not yearly. Not ever. That is, back in the day before people were so irrationally fearful of elemental mercury that our houses had to be evacuated while the hazmat squads came in to dispose of them. (That'll be $10,000 dollars. But don't pay us. You'll get an invoice in the mail.)

If you don't believe me, get some mercury and do the experiment yourself. You can wear special protective clothing and a breathing apparatus if you like. But if you do, please post photos. I'd like to see it. ;-)

However, back (at least closer) to the original topic. If I were given the choice of drinking a gram of mercury or eating a 100mg of methyl-mercury, I'd choose the gram of mercury in a second. Because methyl mercury is a completely different thing than elemental mercury. Just like MoS2 is a different thing than organic molybdenum is a different thing than elemental molybdenum.