Testing the Testing of Mogas

"Jay Honeck" wrote in message
oups.com...
[...]
There are a few questions yet to answer

1. Since isopropyl alchohol is 95% pure, that means that it is 5%
water. Is the tablet fizzing only because of the 5% water?

You can buy "anhydrous isopropyl alcohol". That is, greater than 99% pure.
It may well be technically impossible to get 100% pure alcohol, due to the
presence of water vapor, but obviously the amount of water available in the
air isn't enough to get the tablet to fizz, since it would carry a similar
amount into the regular gasoline with it when you dropped it into there, and
it didn't fizz at all in that.

So, IMHO question #1 is easily answered.

I'm not entirely sure I'm buying the "isopropyl alcohol and ethanol are
chemically similar enough" argument, but I definitely didn't minor in
chemistry, and that was a long time ago. I'm skeptical simply out of
nature, not because I have any real reason to disbelieve Mary's assumption.
Note, however, that they are chemically different enough that one can kill
you right away in small amounts, while the other may take years and years
except in very large doses.

2. However, even if this were the case, would it not also be true that
the presence of ethanol in the car gas would ALSO introduce water, and
thus fizz the alka-seltzer regardless? In other words, is it
irrelevant that the alka-seltzer might only be fizzing because of the
water, if water always accompanies alcohol in gas?

See above. IMHO, while alcohol may bring with it some small quantity of
ambient water vapor absorbed by it, I would be surprised if it were enough
to affect the results of your test. Furthermore, I agree that if a freshly
opened bottle of anhydrous isopropyl alcohol absorbs enough water to be the
sole reason for the tablet fizzing, then surely the alcohol present in gas
would have absorbed enough water to cause the same to happen.

Either way, the fizzing would indicate the presence of water OR
alcohol, or just alcohol that is "saturated" with water -- both of
which would indicate a "No Buy".

Right?

Sure. Though, I'd say that if you need an Alka-Seltzer to tell you that
there is just water in the gas, you're not really trying. Seems to me it's
the alcohol you really care about.

Pete