Tom Buck on wed 14 mar 01
Since Mia asked, I sent the following to her. But now others have
issued quries about the relationship between Barium Carbonate and
Strontium Carbonate. So, here is the chemical data, below.
Tom Buck ) tel: 905-389-2339
(westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
---------- Forwarded message ----------
Date: Mon, 12 Mar 2001 23:49:14 -0500 (EST)
From: Tom Buck
To: Wade Blocker
Subject: Re: strontium carb
Mia:
When you weigh out components of a recipe you really are
"assembling" in a glaze mix a certain amount of moles of the oxide(s) that
persist on the pot when fully fired. and moles are determined by
gram-molecular weights.
hence: Barium Carbonate is BaCO3 which means its molecular weight
is one atom of Barium plus one atom of Carbon plus 3 atoms of Oxygen:
Barium atom wt is 137.3
Carbon a.w. is 12
Oxygen a.w. is 16
therefore the mol wt of BaCO3 is 137.3+12+48=197.3
Strontium Carbonate is SrCO3, ie Sr=87.6; C=12; O3=48. total=147.6
Both mol wts above represent 1 mole of the compound, and when fired the 1
mole becomes the oxide (CO2 is driven off).
So 1 mole of BaO is replaced by 1 mole of SrO from the carbonates
originally --147.6 SrCO3 is equivalent to 197.3 BaCO3, or 100 grams BaCO3
is replaced by 147.6/197.3 x 100 = 74.8 grams (75 is ok because the stuff
is not pure).
The glaze calculation programs yield the molar amounts of the
persistent compounds (those left on the fired pot), so you could work from
the Seger (unity) Formula backwards-- knowing how many moles of BaO are in
the Formula means you can calculate the WEIGHT of SrCO3 by multiplying the
moles (of BaO) by the Mol Wt of SrCO3.
til later. Peace. Tom B.
Tom Buck )
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
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