HomeRoast Digest


Topic: OT: Vacuum Problem PV=nRT (2 msgs / 48 lines)
1) From: Dave Huddle
Before leaving home this AM, I filled my Nissan Leak-Proof Travel Mug
about 2/3 full and closed the lid tightly as I knew I wouldn't be
opening it till after my dentist appoinment.
About 2 hours later, I was unable to open the mug since the coffee had
cooled a little and formed a partial vacuum inside.  I tried using
turning the lid with both thumbs, tried wacking it at the proper angle
with a strong stick, but it was stuck tight!
Then I remembered the ideal gas law, PV=nRT.  Rewriting the equation
as P=nRT/V.  In my situration n, R and V were constant, so P is
directly propotional to T.    I placed my mug on the perimeter heater
in my office and in about 5 minutes both T and P had increased and  I
was able to open it and enjoy my still warm Sumatra Blue Batak.
Next time, I reckon I should fill the mug to full capacity or not
close it so firmly.  (Of course, If I'd filled the mug this AM, it
would have deprived my wife of most of her 2nd cup and caused me a
different problem.)
Dave
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2) From: Bonnie Polkinghorn
Spew Alert Please!  For the first time I had my mug of Aeropressed Moka
Kadir Blend to my lips when I read  PV=nRT - Piv-Nert - brought back
memories of ... well. .... PivNert - and I practically spewed!!  I'm am
laughing so hard because - I'm losing my memory, but I will always remember
PivNert.  Actually, I'm choking, too!
Thanks for the laugh,
Bonnie
On Mon, Dec 21, 2009 at 12:49 PM, Dave Huddle <
137trimethyl26dioxopurine> wrote:
<Snip>
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