Experiments for 'Co'
Below follows a summary of all experiments, matching your search. Click one of the EXPERIMENT hyperlinks for a complete description of the experiment.
Results for 'Co':
EXPERIMENT 1
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Copper and nickel carbonates (basic), which do not dissolve in water, do
dissolve in ammonia, due to formation of a complex with ammonia.
Cobalt carbonate also dissolves, but now an additional reaction occurs,
taking up oxygen from the air.
EXPERIMENT 2
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Aluminum reacts vigorously with water, when its passivating layer of oxide
is effectively destroyed. This can be achieved by using tetrachloro or
tetrabromo complexes of copper (II).
Acid can also be used to destroy the passivating layer, but this takes
considerably more time.
Cobalt has a similar effect as copper (II), but it is less pronounced.
EXPERIMENT 3
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Cobalt builds complexes with thiocyanate, although not very clearly.
EXPERIMENT 4
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Cobalt salts give a nicely colored precipitate with ferrocyanide.
EXPERIMENT 5
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Cobalt builds highly colored complexes with thiocyanate when acetone
is added. This complex is soluble in ether.
EXPERIMENT 6
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Cobalt (II) builds complexes with nitrogen oxides.
EXPERIMENT 7
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Cobalt (II) appears to react with ammonia, but only when an oxidizer
is available. The resulting compound has an intense color.
EXPERIMENT 8
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Cobalt (II) forms a coordination complex with nitrous oxide, which easily
decomposes again. On addition of alkali, the cobalt is oxidized and appears
to build a cobalt-compound of an higher oxidation state.
EXPERIMENT 9
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Cobalt gives a green coordination complex with tartrates, when oxidized to
the +3 state.
EXPERIMENT 10
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Cobalt (II) gives a coordination complex with catechol (or is this due
to formation of a cobalt (III) complex with catechol????).
EXPERIMENT 11
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Cobalt (II) ions build pink aqua complexes are intense blue chloro
complexes. Heat favors the chloro complex.
EXPERIMENT 12
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Cobalt (II) is stable in acidic environments, but in alkaline environments
in the presence of ammonia it reacts with oxygen from the air, resulting
in the formation of a dark red/brown coordination complex.
EXPERIMENT 13
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Cobalt carbonate does not dissolve completely in dilute mineral acids. With
some heating, however, it does dissolve completely.
With nitrite a yellow/orange complex is formed, which forms a precipitate
when treated with alkalies. The precipitate is resistant to treatment with
acid and bases.
EXPERIMENT 14
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Cobalt (II) gives a precipitate with bicarbonate, which probably is
cobalt carbonate. This precipitate is formed, while driving off CO2.
EXPERIMENT 15
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Cobalt (II) gives a blue precipitate with hydroxide, but this precipitate
quickly turns pink / purple / light brown after its formation.
EXPERIMENT 16
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Cobalt (II) gives a deep blue precipitate with silicates.
EXPERIMENT 17
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Cobalt (II) gives a precipitate with bicarbonate, which reacts with hydrogen
peroxide, probably forming a cobalt (III) compound.
EXPERIMENT 18
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Cobalt forms many complexes with ammonia and it forms these complexes
easily, but when cobaltosic oxide (Co3O4, black oxide) is used, then no
such reactions can be observed. Co3O4 appears to be very inert.
EXPERIMENT 19
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Cobalt (II) salts give a blue/green precipitate when dilute ammonia is added.
This precpitate is fairly stable towards air. When more concentrated ammonia
is used, then a dark brown compound is formed, but this compound is formed
by contact with air. On addition of hydrogen peroxide also a very dark
brown compound is formed.
When the pH is increased strongly, then the blue precipitate is not stable
anymore, instead a dark bright blue compound is formed, which, however,
quickly turns pink.
When a large amount of ammonia is replaced by ammonium, then the blue
precipitate is not formed anymore, but a coordination complex is formed,
which is very easily oxidized by oxygen from the air.
EXPERIMENT 20
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Cobalt sulfide does not dissolve in dilute acids and it does not dissolve
in concentrated hydrochloric acid (at least not easily). With the help of
hydrogen peroxide it is possible, however, to dissolve the compound.
EXPERIMENT 21
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Cobalt (II) gives a green precipitate with ferrocyanide and a dark red/
purple precipitate with ferricyanide. The green precipitate cannot be
converted to the red one by means of oxidation by hydrogen peroxide, but
another, dark blue, compound is formed.
EXPERIMENT 22
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Cobalt sulfate dissolves in methanol, albeit not as well as in water. The
liquid obtained is colored quite intensely. The dilute solution of cobalt
sulfate in methanol looks more pink/purple than even the most concentrated
aqueous solution.
With thiocyanate a deep blue complex is formed in methanol.
EXPERIMENT 23
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Borohydride is capable of reducing cobalt (II) to the metallic state.
EXPERIMENT 24
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Cobalt yellow contains the hexanitrito cobaltate (III) complex ion. This
ion is remarkably stable, when it is locked up in the insoluble potassium
salt. With concentrated hydrochloric acid, however, the complex ion is
broken down slowly.
EXPERIMENT 25
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The hexanitrito cobaltate (III) ion can be reduced by SO2 to cobalt (II),
but this reduction requires heating. Some brown compound remains, this
probably is due to the inertness of many cobalt (III) coordination
complexes. With nitrite, a brown complex is formed again. This differs
from the gold/yellow hexanitrito cobaltate (III).
EXPERIMENT 26
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The hexanitrito cobaltate (III) ion is affected by concentrated nitric
acid. It changes from yellow to brown. What is the nature of this change?
EXPERIMENT 27
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The hexanitrito cobaltate (III) ion is stable towards dilute sulphuric acid.
Addition of hydrogen peroxide also does not destroy the yellow complex.
EXPERIMENT 28
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The hexanitrite cobaltate (III) ion is strongly affected by sulfide. A black
compound is formed. On acidification of this, remarkably, no hydrogen
sulfide is formed. Probably the black compound is a compound containing
sulfide and nitrite in a single compound, which on acidification results
in oxidation of the sulfide.
EXPERIMENT 29
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In this experiment, some of Werner's experiments are repeated. Here it is
shown that cobalt forms beautifully colored carbonato complexes. The exact
complex formed, depends on the experimental conditions. It is remarkable
what kinds of reactions are shown by cobalt in its complexes and it is
really difficult to precisely determine what is happening and it even is
difficult already to get the same results without precisely specifying the
exact experimental conditions (e.g. using HCl instead of H2SO4 already
results in a different outcome).
EXPERIMENT 30
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Cobalt (II) chloride hexahydrate is a red/purple compound. When it is heated,
it becomes blue, first dark blue, lateron much lighter blue. The latter
compound is anhydrous cobalt (II) chloride.
Anhydrous cobalt (II) chloride dissolves with a deep blue color in DMSO. With
nitrite, apparently no complex (or a complex with the same color) is formed,
the solution remains deep blue.
The anhydrous cobalt (II) chloride also dissolves in water without problems.
Such solutions are pink. With nitrite these form yellow complexes on
acidification.
Anhydrous cobalt (II) chloride is not soluble in nitromethane.
EXPERIMENT 31
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When hydrated sulfate-salts are heated, which only loose water, then their
properties strongly change. The color changes, but also the solubility
properties change a lot. The sulfate salts loose water easily, but no acid
(H2SO4 or SO3).
EXPERIMENT 32
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Cobalt chloride, both the anhydrous form and the hydrated form (with 6 H2O)
dissolve in acetone, giving a deep blue/cyan solution. When an apolar solvent
is added to this (e.g. ligroin), then the solution of anhydrous cobalt chloride
gives a fine light blue precipitate, the solution of the hydrated cobalt
chloride gives small droplets of deep cyan/blue solution, with a colorless
liquid above it.
EXPERIMENT 33
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The yellow pigment aureolin, also known as cobalt yellow, and having the
chemical name potassium hexanitrito cobaltate(III), can be used as a mild
oxidizer which gives a very smoothly and evenly burning mix with red
phosphorus. When also aluminium powder is added to the mix, then the reaction
is more violent and sparks are sprayed around.
EXPERIMENT 34
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A solution of cobaltous acetate is hydrolysed when the solution is heated. When
the liquid cools down again, then the effect is reversed again. The visual
result is formation of a precipitate on heating and the slow redissolving of
the precipitate on cooling down.
EXPERIMENT 35
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Copper(II) ion and iron(III) ion form complexes with acetyl acetate (acac) in
aqueous solution. Cobalt does not form a complex, at least not visibly.
EXPERIMENT 36
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Cyanate ion forms complexes with many metal ions. These complexes have a strong
color and are not stable in acidic solution.
EXPERIMENT 37
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The hexanitritocobaltate (III) ion is quite stable, but at very low pH, it is
destroyed either by reducing agents, or by coordinating agents. But the nitrito
ligand is MUCH more stable than in the plain nitrite ion.
End of results for 'Co'