General thoughts on the dive physics questions

[tursiops]

Thanks! Now I know why young American scientists do not know chemistry. They teach them a lot of fascinating new stuff but for everyday work in a chemical lab silly trivia is way more important than quantum physics. I'll give you an example from my experience.

One late Monday morning I was approached by a scientist and a tech who asked me to figure out what had happened. Turns out, the tech was running SOP for a large scale DNA isolation. This was not a new task for her, she did this several times already. According to the protocol, the DNA was denatured by alkali, the solution was then put on ice, neutralized with acetic acid, and the DNA was precipitated by methanol. On Friday, the tech performed the denaturation step, then she realized she was running late and she won't be able to do the rest. So she made a sensible (or so it seemed to her) decision to put the stuff (a 2 L conical flask with about 0.5 L solution in it) into the fridge and get back to it on Monday.

On Monday, however, adding acetic acid resulted in foaming and the content of the flask ran out into the ice bucket and all over the bench. Whoa, what happened?! The guy has a PhD, BTW, and he could not figure this out. Guess, he did not memorize the silly trivia.

And did you give a straight answer to his question, or did you make fun of him like you do on SB?

 

[Storker]

And did you give a straight answer to his question, or did you make fun of him like you di on SB?

Not knowing is excusable and should be rectified in a polite way.

Not wanting to know is never excusable and may well be mocked.

 

[Jcp2]

Mocking may not work when the mocked party really doesn't care.

 

[Akimbo]

I have a chemistry book from the early 50s which states that there is no known commercial use for silicone.

I must be missing your intent. What about glass?

For many years following its discovery, it [helium] was said to have no practical use.

Sincere question: By discovery, do you mean 1868 when Helium was discovered or in 1903 when commercial quantities were discovered?

Diving History Note:
The US Bureau of Mines suggested using Helium-Oxygen as a breathing mixture in 1915 after the submarine F-4 sank in 306'/93M. They were looking for a use beyond nonflammable lighter than air balloons.

 

[tarponchik]

I must be missing your intent. What about glass?

He probably meant silicon, not silicone. Neither is used to make glass; silicon dioxide is.

 

[Akimbo]

He probably meant silicon, not silicone. Neither is used to make glass; silicon dioxide is.

Silica, or silicon dioxide (SiO2) is one part silicon??? The main point is I still don't understand why any chemist would not find silicon useful since it was widely used long before the element was defined/discovered? Silicone, the synthetic substance also known as polysiloxane, is new enough (1901) that I would think the developer would have imagined all kinds of uses for its unique properties. Not trying to argue, just to understand the comment.

 

[Storker]

Silica, or silicon dioxide (SiO2) is one part silicon??? The main point is I still don't understand why any chemist would not find silicon useful since it was widely used long before the element was defined/discovered? Silicone, the synthetic substance also known as polysiloxane, is new enough (1901) that I would think the developer would have imagined all kinds of uses for its unique properties. Not trying to argue, just to understand the comment.

Silicon: the element. Si
Silica: the oxide. SiO2. AKA quartz, or sand.
Silicone: a polymer consisting of silicon, oxygen and carbon.

They have as much to do with each other as chlorine gas (Cl2, the warfare gas from WW1) has to do with table salt (NaCl) or PVC.

And just to be really anal: The ratio of Si to O in SiO2 is 1:2 on a molar basis, and 1:1.14 on a mass basis.