# Last edited on 2016-12-19 21:33:40 by stolfilocal

Preparing basic copper carbonate in various conditions

In 2016-09 (??), three small batches of basic copper carbonate were
prepared by wash solutions of the "copper_chloride" experiment.

Solution (W1) was the result of washing the CaSO4(H2O)2 precipitate
with water. It contained mostly CuCl2, some CuSO4 (that was
intentionally used in slight excess), and a bit of dissoved CaSO4. It
should have contained no CaCl2.

Solution (W2) was the result of washing the residue (P4) left
after the ethanol extraction of the CuCL2, with water.  It 
probably contained mostly CuSO4, maybe a tiny bit of CaSO4 and
other impurities.  No CuCl2 and no CaCl2.

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2016-09-??

To remove copper from the wash (W1), 100 ml of a saturated solution (S4) of NaHCO3
was prepared, at 20 C (pH ~8), decanted and filtered with 201 paper.

Then 12 ml of this solution (S4) was added to the wash (W1), resulting in a light
blue ppt, assumed to be basic copper carbonate Cu2(OH)2CO3 according to
Wikpedia. A small amount of gas was released.

The ppt (P2) was allowed to settle, but would not settle completely. Filtered
with coffee filter, the filtrate was still milky. Added 1 ml more of
NaHCO3 solution (S4), but was not clear whether it reacted further; the
suspension was too cloudy.

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2016-09-11 [3]

To dispose of the wash (W2), dissolved 15 g of NaHCo3 in 120 ml
of water heated to ~55 C, then cooled to get saturated solution (S6).

* Reacted at 90 C: some of the wash solution (W2) (filtered) and some NaHCO3
solution (S6). Fast release of lots of CO2, with a veronese green ppt (P6).

* Reacted at 10 C: ~130 g of wash solution (W2) (filtered) and 61 g of the
NaHCO3 solution (S6). Slow (hours) release of CO2, and a turquoise blue ppt (P7).

Filtered and washed the ppts (P6) and (P7) yielding filtrates + wash 
(W6) and (W7), respectively.

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2016-09-13

The filtrate plus wash (W7) of the 10 C reaction developed a thin iridescent
film on the surface.

The washes (W6) and (W7) were discarded.

The three samples (P2), (P6) and (P7) were dried and stored.  The
containers of (P6) and (P7) were stoppered with paper (not gas tight).
The container of (P2) had a screw-on lid.

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2016-12-18

More than three months later, the three samples (P2), (P6), and (P7)
were taken out of their containers and compared side by side, after
being lightly crumbled to similar grain sizes. No difference was seen,
except that the lumps of (P2) had a slight whitish tinge on the
surface, before they were crumbled.

Merged the three samples (12 g total) in one storage pot.