ORIGINAL: Lobster
ORIGINAL: stuart3
ORIGINAL: Lobster
The evaporation rate has a lot to do with how much surface area is exposed regardless of what the subject is. One square centimeter would take an exceptionally long time at room temperature (`70F). The surface area in the plastic tub in the demonstration is considerably more than one square centimeter.
And regardless of, 'don't do this at home', you know how rampant stupidity is in the world.[:D]
Even before the advent of Youtube people did stupid things. A friend and a friend of his decided they would make an explosive. I think gunpowder. They gathered the ingredients and while the friend of a friend was mixing some ingredients together they exploded in a pestle he was holding. So, the friend of a friend has the honor of only one hand and a badly scared neck, chest and arms. It almost killed him.
So I do have reason to take exception when a knowledgeable individual shows stupid people how to do dangerous things. [;)]
Mercury isn't difficult to come by if you have an account with a supplier, but it's expensive. I dread to think how much that lot cost.
When the evaporation rate is negligibly small then the total amount in the atmosphere remains essentially zero, however much mercury is there and however long it is present.
When they tore up the original wooden block floor in one of the labs I used to work in, they found quite a large pool of mercury underneath which had obviously dripped through the gaps between the blocks sometime in the past. I'm sure it wasn't spilled during my time there so it must have been there for many years. But as it doesn't evaporate at room temperature, no problem. I just cleaned it up for the worried building contractors. [:)]
If you are still worried about him breathing in any harmful vapor that might magically have escaped into the atmosphere, well he was working in the open air, not in a confined space.
But it DOES evaporate at room temperature. [:D]
One square centimeter would take somewhere in the neighborhood of 8200 hours to evaporate. That's a one square centimeter globule. At room temperature. That's about a year. It's prolonged exposure that becomes a problem. Being in a class where you spend maybe four hours maximum for a handful of days a week for a few months, even if you are the prof, wouldn't be a problem. If you lived there for years and there was mercury present the whole time then you might have health issues.
This is how it happens:
In 1989, several pounds of liquid mercury spilled in a child's bedroom. The mercury was not cleaned up sufficiently. He and his two sisters continued to be exposed to high levels of evaporating mercury for a prolonged period, and they suffered serious health consequences. (Source: CDC.gov)
Stupid people do stupid things. Someone will try to do this very same thing without any knowledge of what they are doing. You can take that to the bank. [;)]
Where did you come by the information to calculate the time it takes to evaporate? The Material Safety Data Sheet states that no information is available for the Evaporation Rate. (Section 9 - Physical and Chemical properties). That means that even Fisher Scientific couldn't make that calculation.
https://www.fishersci.com/store/msds?pa ... anguage=en
It's tragic about the kids of course, but you can't take a domestic bedroom situation where the kids may be playing with spilled mercury, even putting it in their mouths because their parents don't know the hazards involved, and compare it with a laboratory spill or a You Tube demonstration where the people involved have the professional knowledge to know how much respect they have to give chemicals without going over the top.
; Julia Child
