[meteorite-list] Is there room for a meteorite question ?
From: Kevin Fly Hill <khill_at_meteoritecentral.com>
Date: Thu Apr 22 10:17:45 2004 Message-ID: <004601c3c0bf$a40ce1a0$6d00a8c0_at_coxinternet.com> This is a multi-part message in MIME format. ------=_NextPart_000_0043_01C3C08D.58A90720 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Doug, Great explaination ! It's been a long time since Chemistry class -- and = we never got that deep. I guess I can turn off the melting pot and put = that 10 lb Campo back on the shelf. One question, though. You stated "since water (0.92 g/mL) in = equilibrium at 0=C2=B0C is denser than ice (1.00 g/mL)." =20 Did you mean that the other way? Water at 1.00 g/mL ? Thanks Fly Hill ----- Original Message -----=20 From: MexicoDoug_at_aol.com=20 To: khill_at_cpsmedical.com ; meteorite-list@meteoritecentral.com=20 Sent: Thursday, December 11, 2003 10:43 PM Subject: Re: [meteorite-list] Is there room for a meteorite question ? And for a more complete stab at answering your question from a proud = "newbee". Note you really asked two questions. =20 1. If upon cooling there is expansion and 2. If the density is the = same as non-crystalline materials formed on earth in the same ally = proportions.=20 To question 1: If I understand your question properly at first reading = you think that Fe-Ni mixtures upon cooling in the proper proportions = forming taenite / kamacite might expand? No way. Those structures do = not form until after the alloy is already solid, though in an amorphous = (non-crystalline) state with selective atom mobility. Those migrations = of atoms occur to release heat energy flowing out of the system because = of decreasing boundary temperatures and the law of heat flowing from = higher to colder temperatures. The migrations are happening as these = new crystal structures settle down from vibrations and fall into their = little unit cells, allowing for a more dense material. For an expansion = they would have to rip apart the already developed solid = structure...causing perhaps a very brittle substance even. Now your other question, whether the "terrestrial" amorphous material = has the same density as a "crystalline" meteorite material. That's = something I'm sure you know if you think a minute. Of course it does = not have the same density. So save your iron meteorites for better = experiments, and don't melt them to see. The amorphous material = probably won't even have as an extremely precisely definable density. = It ought to vary because it is amorphous. Whether statistics averages = the density out or not is a separate question and of course will depend = on exactly what alloy %'s you have and how well they are mixed on a = macro scale...the history of how the sample was cooled, etc. Does = graphite have the same density as diamond? No. You cite water, when freezing, as expanding as your model, since water = (0.92 g/mL) in equilibrium at 0=C2=B0C is denser than ice (1.00 g/mL). = Water is weird, and one of the anomalous things that explains life. The = short answer on why it expands upon decreasing temperature at = atmospheric pressure from 4=C2=B0C to 0=C2=B0C is a softening of proton = (hydrogen) bonding and disruption of that nicely organized structure as = it is an ionic (solution) type attraction that is destroyed as the = molecules begin to fall down from their bounciness caused by higher = temperatures. So the destruction of the hydrogen bonds happens upon = cooling. Another way to say that is the melting of the hydrogen bonds = upon cooling=E2=80=A6 In its amorphous, hydrogen-bondless state oxygen = atoms find themselves not tolerating such close density as before when = all were moderated by the hydrogen atoms. So they repel each other an = average of about 8% volume increase. Water would be less than 0.92 g/mL = at room temperature if not for the hydrogen bonding. Probably about = 0.90, and then it would behave like most of the other molecules upon = freezing. There are no comparably scaled ionic like attractions going on in the = metal alloys as they cool. So there is no comparison to the special = case of water. Additionally, you should know that water ice has about = 20 described crystalline structures, and they are, not coincidentally, = not all the same density! You need to know the history of it. Do you = think super cooled hail is the same as the cubes floating in your ice = tea? No. And the rockhounds can probably come up with a good list of = structures with different densities but the same molecular proportions. Every sample is individual: so back to the meteorite experiment. Each = meteorite has a different history as in temperatures and pressures. = Each has different impurities, so you will need to do more that just = reproduce the alloy proportions...actually by now it seems pretty clear = that the proposed experiment is not a good idea. All those impurities = disrupt perfect conditions. So oceans don't freeze at 0=C2=B0C, they = are a few degrees colder, because of the impurities. All that affects = densities, not to mention any molecular flatulence causing micro pores, = uniformly or not. Ooops. Just checking to see if anyone read this = far... PS Ice floats. Can you imagine solid pieces of metal alloy floating = as it is melted...that was the easier explanation... Saludos Doug Dawn Mexico En un mensaje con fecha 12/11/2003 2:58:13 PM Mexico Standard Time, = khill_at_cpsmedical.com escribe: Question: When water turns to ice the change to a crystal = structure expands the volume (decreases density). Does this density/expansion = change also occur with the development of taenite/kamacite lattices? ie. at the same temperature is the density of an iron = meteorite match the density of a "terrestrial" matching mixture that is "noncrystalline"? Guess you could melt down one of your irons and = compare? Fly Hill >----- Original Message -----=20 >From: "mark ford" <markf_at_ssl.gb.com> >To: <meteorite-list_at_meteoritecentral.com> >Sent: Tuesday, December 09, 2003 8:41 AM >Subject: RE: [meteorite-list] Is there room for a meteorite = question ? > > >> >> >> >> >> >>On the same note, thermal expansion... >> >>Presumably as the core solidifies (cools down) it would contract, = would >>it not?, what effect would that have on the crystalline structure >>(widmanstatten) would there be a gradual stress/distortion in the >>taenite/kamacite boundries ? >> >> >>I guess as the core is such a big mass, any significant thermal >>contraction distortion would hardly be noticeable in a small hand >>specimen but I would imagine the thermal contraction in something = the >>size of a large planetary body would be massive. >> >> >> >>Mark Ford >> >> >> >> > = >------------------------------------------------------------------------=
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<DIV><FONT face=3DArial size=3D2>Doug,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>
<DIV><FONT face=3DArial size=3D2>Great explaination ! It's been a =
long time=20
since Chemistry class -- and we never got that deep. I guess I can =
turn=20
off the melting pot and put that 10 lb Campo back on the =
shelf.</FONT></DIV>
<DIV> </DIV></FONT></DIV>
<DIV><FONT face=3DArial size=3D2>One question, though. You =
stated "since=20
water (0.92 g/mL) in equilibrium at 0=C2=B0C is denser than ice (1.00 =
g/mL)." =20
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Did you mean that the other way? =
Water at=20
1.00 g/mL ?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Thanks</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Fly Hill</FONT></DIV>
<BLOCKQUOTE=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<A title=3DMexicoDoug_at_aol.com=20
href=3D"mailto:MexicoDoug_at_aol.com">MexicoDoug@aol.com</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Dkhill_at_cpsmedical.com=20
href=3D"mailto:khill_at_cpsmedical.com">khill@cpsmedical.com</A> ; <A=20
title=3Dmeteorite-list_at_meteoritecentral.com=20
=
href=3D"mailto:meteorite-list_at_meteoritecentral.com">meteorite-list@meteor=
itecentral.com</A>=20
</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Thursday, December 11, =
2003 10:43=20
PM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> Re: [meteorite-list] =
Is there=20
room for a meteorite question ?</DIV>
<DIV><BR></DIV><FONT face=3Darial,helvetica><FONT lang=3D0 =
face=3DArial size=3D2=20
FAMILY=3D"SANSSERIF">And for a more complete stab at answering your =
question=20
from a proud "newbee". Note you really asked two =
questions. =20
<BR><BR>1. If upon cooling there is expansion and 2. If the density is =
the=20
same as non-crystalline materials formed on earth in the same ally=20
proportions. <BR><BR>To question 1: If I understand your question =
properly at=20
first reading you think that Fe-Ni mixtures upon cooling in the proper =
proportions forming taenite / kamacite might expand? No =
way. Those=20
structures do not form until after the alloy is already solid, though =
in an=20
amorphous (non-crystalline) state with selective atom mobility. =
Those=20
migrations of atoms occur to release heat energy flowing out of the =
system=20
because of decreasing boundary temperatures and the law of heat =
flowing from=20
higher to colder temperatures. The migrations are happening as =
these new=20
crystal structures settle down from vibrations and fall into their =
little unit=20
cells, allowing for a more dense material. For an expansion they =
would=20
have to rip apart the already developed solid structure...causing =
perhaps a=20
very brittle substance even.<BR><BR>Now your other question, whether =
the=20
"terrestrial" amorphous material has the same density as a =
"crystalline"=20
meteorite material. That's something I'm sure you know if you =
think a=20
minute. Of course it does not have the same density. So =
save your=20
iron meteorites for better experiments, and don't melt them to =
see. The=20
amorphous material probably won't even have as an extremely precisely=20
definable density. It ought to vary because it is =
amorphous. =20
Whether statistics averages the density out or not is a separate =
question and=20
of course will depend on exactly what alloy %'s you have and how well =
they are=20
mixed on a macro scale...the history of how the sample was cooled, =
etc. =20
Does graphite have the same density as diamond? No.<BR><BR>You =
cite=20
water, when freezing, as expanding as your model, since water (0.92 =
g/mL) in=20
equilibrium at 0=C2=B0C is denser than ice (1.00 g/mL). Water is =
weird, and=20
one of the anomalous things that explains life. The short answer =
on why=20
it expands upon decreasing temperature at atmospheric pressure from =
4=C2=B0C to 0=C2=B0C=20
is a softening of proton (hydrogen) bonding and disruption of that =
nicely=20
organized structure as it is an ionic (solution) type attraction that =
is=20
destroyed as the molecules begin to fall down from their bounciness =
caused by=20
higher temperatures. So the destruction of the hydrogen bonds =
happens=20
upon cooling. Another way to say that is the melting of the =
hydrogen=20
bonds upon cooling=E2=80=A6 In its amorphous, hydrogen-bondless =
state oxygen=20
atoms find themselves not tolerating such close density as before when =
all=20
were moderated by the hydrogen atoms. So they repel each other =
an=20
average of about 8% volume increase. Water would be less than =
0.92 g/mL=20
at room temperature if not for the hydrogen bonding. Probably =
about=20
0.90, and then it would behave like most of the other molecules upon=20
freezing.<BR><BR>There are no comparably scaled ionic like attractions =
going=20
on in the metal alloys as they cool. So there is no comparison =
to the=20
special case of water. Additionally, you should know that water =
ice has=20
about 20 described crystalline structures, and they are, not =
coincidentally,=20
not all the same density! You need to know the history of =
it. Do=20
you think super cooled hail is the same as the cubes floating in your =
ice=20
tea? No. And the rockhounds can probably come up with a =
good list=20
of structures with different densities but the same molecular=20
proportions.<BR><BR>Every sample is individual: so back to the =
meteorite=20
experiment. Each meteorite has a different history as in =
temperatures=20
and pressures. Each has different impurities, so you will need =
to do=20
more that just reproduce the alloy proportions...actually by now it =
seems=20
pretty clear that the proposed experiment is not a good idea. =
All those=20
impurities disrupt perfect conditions. So oceans don't freeze at =
0=C2=B0C,=20
they are a few degrees colder, because of the impurities. All =
that=20
affects densities, not to mention any molecular flatulence causing =
micro=20
pores, uniformly or not. Ooops. Just checking to see if =
anyone=20
read this far...<BR><BR>PS Ice floats. Can you imagine solid =
pieces of=20
metal alloy floating as it is melted...that was the easier=20
explanation...<BR><BR>Saludos<BR>Doug Dawn<BR>Mexico<BR><BR>En un =
mensaje con=20
fecha 12/11/2003 2:58:13 PM Mexico Standard Time, khill_at_cpsmedical.com =
escribe:<BR><BR>
<BLOCKQUOTE=20
style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px =
solid; MARGIN-RIGHT: 0px"=20
TYPE=3D"CITE"><BR><BR><BR>Question: When water turns to =
ice the=20
change to a crystal structure<BR>expands the volume (decreases=20
density). Does this density/expansion change<BR>also occur =
with the=20
development of taenite/kamacite<BR>lattices? ie. at the =
same=20
temperature is the density of an iron meteorite<BR>match the density =
of a=20
"terrestrial" matching mixture that is<BR>"noncrystalline"? =
Guess you=20
could melt down one of your irons and compare?<BR><BR>Fly=20
Hill<BR><BR>>----- Original Message ----- <BR>>From: "mark =
ford"=20
<markf_at_ssl.gb.com><BR>>To:=20
<meteorite-list_at_meteoritecentral.com><BR>>Sent: Tuesday, =
December=20
09, 2003 8:41 AM<BR>>Subject: RE: [meteorite-list] Is there room =
for a=20
meteorite question=20
=
?<BR>><BR>><BR>>><BR>>><BR>>><BR>>><BR>>=
><BR>>>On=20
the same note, thermal =
expansion...<BR>>><BR>>>Presumably as the=20
core solidifies (cools down) it would contract, would<BR>>>it =
not?,=20
what effect would that have on the crystalline=20
structure<BR>>>(widmanstatten) would there be a gradual=20
stress/distortion in the<BR>>>taenite/kamacite boundries=20
?<BR>>><BR>>><BR>>>I guess as the core is such a =
big mass,=20
any significant thermal<BR>>>contraction distortion would =
hardly be=20
noticeable in a small hand<BR>>>specimen but I would imagine =
the=20
thermal contraction in something the<BR>>>size of a large =
planetary=20
body would be =
massive.<BR>>><BR>>><BR>>><BR>>>Mark=20
=
Ford<BR>>><BR>>><BR>>><BR>>><BR>><BR>>-----=
---------------------------------------------------------------------<BR>=
>--<BR>>>The=20
information contained in this email may be commercially=20
sensitive<BR>>and/or<BR>>>legally privileged. It is =
intended solely=20
for the person(s) to whom it<BR>is<BR>>>addressed. If you are =
not a=20
named recipient, you are on notice of =
its<BR>>status.<BR>>>Please=20
notify the sender immediately by reply e-mail and then=20
delete<BR>this<BR>>>message from your system. You must not =
disclose it=20
to any other person,<BR>>>copy or distribute it or use it for =
any=20
=
purpose.<BR></BLOCKQUOTE><BR><BR></BLOCKQUOTE></FONT></FONT></BODY></HTML=
>
------=_NextPart_000_0043_01C3C08D.58A90720--
Received on Fri 12 Dec 2003 09:53:00 AM PST
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