Experiments for 'hydrochloric acid'
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 'hydrochloric acid':
EXPERIMENT 1
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Tetra chloro auric acid (a.k.a. "gold chloride"), a gold (III) compound is
easily reduced to metallic gold, which forms a colloidal solution. With
strong reductors, the gold particles formed are so large that they form
a dark precipitate.
EXPERIMENT 2
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Nitrite is decomposed by hydrochloric acid (as it is done by all acids),
but when the decomposition products are not allowed to escape, then
further reactions occur.
When bromide is added, then a compound is formed, which definitely is not
bromine. What is this compound?
When iodide is added, then iodine is formed.
EXPERIMENT 3
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Nitrous vapors react with thiocyanate, building a red/brown compound, which
disappears again, when left in contact with air.
EXPERIMENT 4
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Thiocyanate reacts with nitrogen dioxide to form a red/brown compound. It
does not react with nitrogen monoxide. When a reaction occurs with NO2,
a white fume is produced.
EXPERIMENT 5
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When nitric acid is mixed with hydrochloric acid, then so called aqua regia
is obtained. This is a colorless liquid, which, however, is not very stable
and which decomposes. What are the decomposition products?
EXPERIMENT 6
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Nitrites react with concentrated hydrochloric acid, forming a brown/orange
compound, which remains dissolved in the acid. When the acid is diluted
with water, then this orange compound is destroyed (probably it hydrolyses,
due to lower concentration).
EXPERIMENT 7
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Methanol gives a colorless gas with nitrite in acidic media. No formation
of NO/NO2. This compound probably is CH3ONO, the nitrite ester of methanol.
The large excess of CH3OH does not prevent formation of nitrosyl thiocyanate.
EXPERIMENT 8
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Methanol and nitrate/nitric acid do not react readily, not even at fairly
high temperature (appr. 90C).
EXPERIMENT 9
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Hydrogen cyanide (or cyanide salt) slowly changes to a dark brown/black
compound, when it is allowed to stand. At least this happens in strongly acidic
media.
EXPERIMENT 10
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Vanadyl (vanadium (IV)) does not give a coordination complex with ammonia.
It does not dissolve in ammonia. With stronger bases, a brown vanadate (IV)
compound dissolves (a poly-vanadate (IV) compound??).
EXPERIMENT 11
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Vanadium(III) hydroxide apparently forms a precipitate and does not
dissolve in strongly alkaline liquids.
Vanadium (III) and (IV) are oxidized by peroxodisulfate to vanadium (V).
EXPERIMENT 12
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Vanadium (III) apparently builds a coordination complex with EDTA in
strongly acidic environments. This complex is brown.
EXPERIMENT 13
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Hydroxyl amine is capable of reducing vanadium (V) to vanadium (IV), but
further reduction is not possible with hydroxyl amine.
EXPERIMENT 14
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Vanadyl ions apparently do not form a coordination complex with chloride at
extremely high concentration, or the coordination complex has the same color
as the vanadyl-aqua complex.
EXPERIMENT 15
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Vanadium (V) is capable of forming many peroxo compounds, whose appearance
strongly depends on pH.
EXPERIMENT 16
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Vanadyl ion is not reduced by borane to vanadium in a lower oxidation state.
EXPERIMENT 17
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Copper (II) reacts with thiocyanate in a complex way.
EXPERIMENT 18
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Copper (II) reacts with thiocyanate in a complex way.
EXPERIMENT 19
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Vitamin C is a strong reductor in alkaline environments. Copper (II) is
reduced to copper (I).
EXPERIMENT 20
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Copper hydroxide is decomposed upon heating and loses water, even if
it is surrounded by water.
EXPERIMENT 21
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Copper is oxidized by a mix of concentrated hydrochloric acid and
hydrogen peroxide. When the peroxide is used up and there is still an
excess amount of hydrochloric acid, then the copper (II) appears to
oxidize the copper metal, under the formation of an intensely colored
complex. (What is the constitution of this complex??)
When the solution is diluted with water, then the intensely colored
complex is destroyed and a white crystalline precipitate of CuCl is
formed. If too much water is used, then no clear precipitate is formed.
EXPERIMENT 22
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Copper (II) reacts with metallic copper, in the presence of a large amount
of hydrochloric acid, forming an intensely colored compound. This compound
contains copper (I). If copper (II) is used alone, with hydrochloric acid
and peroxide, then the strong coloration does not occur.
EXPERIMENT 23
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Hydroquinone is capable of reducing copper (II) to copper (I) in alkaline
environments. The copper is not reduced to its metallic form.
EXPERIMENT 24
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Metol is capable of reducing copper (II) to copper (I) in alkaline
environments.
EXPERIMENT 25
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Copper gives a coordination complex with catechol, but only in alkaline
environments. This complex is easily oxidized by oxygen from air. Iron
also forms a complex in acidic media, probably by a combined red/coordination
reaction.
EXPERIMENT 26
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When copper (II) is reduced by dithionite in neutral environments, then
a dark red/brown precipitate is formed (metallic copper??). When reduced
in alkaline environments, then hydrous copper (I) oxide is formed.
EXPERIMENT 27
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When tetraammine-copper (II) is reduced by dithionite in excess ammonia,
then a colorless copper (I) complex is formed, which remains dissolved.
EXPERIMENT 28
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Decomposition of hydrogen peroxide is catalyzed by cuprammine complex.
EXPERIMENT 29
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Copper (II) reacts with thiourea, forming a pale/yellow precipitate, looking
like sulphur. This precipitate, however, is not sulphur (what is it???).
EXPERIMENT 30
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Hydroxyl amine sulfate (containing protonated hydroxyl amine) is not capable
of reducing copper (II). When the liquid becomes basic (releasing free
hydroxyl amine), then the copper (II) is reduced to copper (I).
EXPERIMENT 31
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Copper builds a remarkable complex with ascorbic acid and is easily
reduced by ascorbic acid in alkaline environments. Copper (II) builds
a brown compound with hydrogen peroxide in alkaline environments.
EXPERIMENT 32
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Copper (II) is reduced by sulfite. With chloride the resulting copper (I)
can be kept in solution. The copper (I) compound is very susceptible
to oxidation by oxygen from the air.
EXPERIMENT 33
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Nitrous acid (or its decomposition product) forms a dark brown coordination
complex with ferric ions. With copper (II) also a coordination complex is
formed. In relatively strongly acidic environments, these coordination
complexes are destroyed/not formed.
EXPERIMENT 34
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When copper dissolves in aqua regia, then a colorless gas is produced.
Oxidation apparently proceeds in a different way, when compared with
dissolving copper in nitric acid.
EXPERIMENT 35
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Copper (II) builds a coordination complex with acetate ions. On addition
of hydrogen peroxide, this complex is destroyed and a new compound is
formed.
EXPERIMENT 36
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Copper (II) is reduced by hydroxyl amine very quickly in alkaline
environments. Yellow copper (I) hydroxide/oxide is formed.
EXPERIMENT 37
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Copper (II) salts give a cyan precipitate with bicarbonates. The color of
this precipitate is the same as the color of commercially available basic
copper carbonate.
This precipitate reacts with hydrogen peroxide, forming a dark green/brown
compound. With sulfite it also reacts, forming a brownish compound, which
on acidification dissolves, forming a light yellow/brown clear liquid.
EXPERIMENT 38
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Copper (II) is reduced by metabisulfite / sulphur dioxide to a copper (I)
compound, but some heating is required in order to make this reaction
fast.
EXPERIMENT 39
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When copper (II) is present in hydrochloric acid, then it does not react
immediately with hydroxyl ammonium, some heating is required to have a
reaction, resulting in formation of a dark green/brown compound. When the
liquid is made alkaline with excess ammonia, then it quickly becomes
colorless, due to reduction of copper (II) to copper (I), which forms a
colorless complex with ammonia.
A very peculiar reaction occurs on oxidation by oxygen from air. The liquid
is covered by a very thin shiny layer, looking like a strongly coloured oil
on water. It is not clear what it is, more research is needed.
EXPERIMENT 40
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Cupric chloride forms a coordination complex when a large excess of chloride
is present and this chloro cuprate complex easily oxidizes metallic copper.
This oxidation causes formation of copper (I), which forms a very dark
brown complex in the presence of copper (II) and hydrochloric acid (what
is this dark brown compound?).
EXPERIMENT 41
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Nitrite forms a dark green coordination complex with copper (II) ions in
neutral environments. When acidified, then a new coordination complex
(dark blue with a grey hue) is formed in the presence of chloride of
very high concentration. This is not formed when chloride is absent.
EXPERIMENT 42
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Copper (II) carbonate gives a very dark compound with H2O2, is this a
peroxide compound or just copper oxide?
EXPERIMENT 43
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Copper (II) forms a yellow/brown coordination complex with cyanide in
acidic media in the presence of chloride.
EXPERIMENT 44
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Copper (I) oxide, when added to sulphuric acid, disproportionates. Metallic
copper is formed and a blue solution of copper (II) sulfate. The copper (I)
oxide looses its oxide ion to the acid and that would leave aqueous copper (I)
ions. These are not stable and disproportionate at once.
Copper (I) oxide, added to hydrochloric acid dissolves and forms a solution,
containing a copper (I) complex, [CuCl2]-. This complex is very easily oxidized
by oxygen from the air and then a dark brown mixed valency complex of copper
(I) and copper (II) is formed.
EXPERIMENT 45
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Copper(I) iodide dissolves in a concentrated solution of potassium iodide.
In such a solution the complex ion CuI2(-) is formed. On dilution, this ion
decomposes and a precipitate of CuI is formed again.
Copper(I) iodide does not dissolve in hydrochloric acid, or just a small
amount dissolves.
EXPERIMENT 46
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This is a very nice experiment, involving beautifully coloured compounds,
but it is a hazardous experiment as well, due to the use of mercury (II)
compounds.
Mercury (II) builds a complex with excess iodide, [HgI4]2-, which gives a
beautiful bright yellow precipitate with Ag+ and a beautiful bright brick-
red precipitate with Cu+.
EXPERIMENT 47
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Palladium (II) is not oxidized by H2O2 in acidic environments.
EXPERIMENT 48
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Palladium (II) is not easily reduced by mild reducing agents. Only very
strong reductors are capable of reducing this to metallic palladium.
Strong oxidizers probably are capable of oxidizing palladium (II) to a
higher oxidation state, but if this is true, then the higher oxidation
state has almost the same color.
Sulfite, instead of reducing palladium to the metallic state, appears to
form a brightly colored coordination complex in acidic environments.
EXPERIMENT 49
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Platinum (II) can be oxidized to platinum (IV) by strong oxidizing agents.
Reduction to metallic platinum cannot be achieved by sulfite nor by stannous
chloride.
EXPERIMENT 50
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Platinum (II) gives a highly coloured compound with tin (II), it is not
reduced to metallic platinum.
EXPERIMENT 51
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Platinum(II) is not reduced by sulfide in acidic environments. When it is
treated with stannous ions at the same time, then a dark brown compound
is formed, but probably this is not metallic platinum but stannous sulfide.
What speaks against this is that stannous chloride does not precipitate
with H2S in acidic environments (see sequence 2), while with the Pt-compound
a dark brown compound is formed. More research will be needed to resolve
this.
EXPERIMENT 52
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Palladium probably gives a very finely divided metallic compound, when it is
reduced by stannous chloride. The intense colors, appearing in this
experiment probably are caused by colloidal solutions.
EXPERIMENT 53
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Titanium dissolves in dilute hydrochloric acid with great difficulty. When
hydrofluoric acid is present as well, then the metal dissolves easily. A
tinanium (III) fluoro complex is formed.
EXPERIMENT 54
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Titanium slowly dissolves in concentrated hydrochloric acid, forming deep
blue/violet titanium (III) ions. On addition of hydrogen peroxide these are
oxidized to titanium (IV), which in turn forms a deep red coordination
complex with hydrogen peroxide.
The deep red coordination complex is only stable in acidic to neutral media.
It also is easily reduced by nitrite. It is not affected strongly by
persulfate. With fluoride, a light yellow compound is formed, but the
formation of that may also be due to rise of pH.
EXPERIMENT 55
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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 56
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Bismuth shows remarkable coordination chemistry with iodide and chloride.
In the absence of chloride, a black precipitate of BiI3 is formed. In the
presence of chloride, a deep yellow/orange compound is formed, but only
if also iodide is present. So this compound must be a complex of bismuth,
iodide and chloride.
EXPERIMENT 57
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Bismuth (III) forms a deep-orange iodo-complex and a yellow iodo-chloro
complex.
EXPERIMENT 58
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Cobalt (II) builds complexes with nitrogen oxides.
EXPERIMENT 59
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Cobalt gives a green coordination complex with tartrates, when oxidized to
the +3 state.
EXPERIMENT 60
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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 61
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Cobalt (II) ions build pink aqua complexes are intense blue chloro
complexes. Heat favors the chloro complex.
EXPERIMENT 62
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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 63
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Cobalt (II) gives a precipitate with bicarbonate, which reacts with hydrogen
peroxide, probably forming a cobalt (III) compound.
EXPERIMENT 64
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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 65
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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 66
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Borohydride is capable of reducing cobalt (II) to the metallic state.
EXPERIMENT 67
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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 68
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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 69
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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 70
---------------
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 71
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Sulfide gives precipitates with some metals, which do not dissolve in
strong acids. These sulfides, however, can easily be dissolved, when an
oxidizing agent is used.
Sulfide is easily oxidized by moderately strong oxidizers.
EXPERIMENT 72
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This sequence of experiments shows that sulfite is capable of reducing
silver (I), copper (II) and iron (III), but that these reactions all
show their own peculiarities. Sulphur in the +4 oxidation state is a
mild reductant.
EXPERIMENT 73
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Sodium sulfide is oxidized by acidic hydrogen peroxide with extreme violence.
EXPERIMENT 74
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Molybdate gives rise to all kinds of complexes, when combined with reducing
agents. These complexes can be yellow, green or blue. The composition of
all these complexes is not very clear.
EXPERIMENT 75
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Molybdate gives a yellow complex with iodide. Order of dissolving and
acidifying has influence on the reactions observed.
EXPERIMENT 76
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Hydroquinone is oxidized by ferric chloride to quinone. An intermediate
dark green compound is formed before all hydroquinone is oxidized.
EXPERIMENT 77
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Hydroquinone can be oxidized by ferric chloride. If not too much ferric
chloride is added, then a coordination complex of the oxidation product
with hydroquinone is formed and crystals of this compound separate
from the liquid.
EXPERIMENT 78
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Photography developers, based on phenol-like structures, are easily oxidized
by air in alkaline environments and the oxidation products are such, that
a reverse process does not occur anymore (probably the oxidation products
are large polymerized species).
EXPERIMENT 79
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Pyrogallol is quickly oxidized in alkaline environments by oxygen from the
air. The more alkaline, the faster this reaction proceeds.
The black oxidation products are affected by acid, but the pyrogallol is
not recovered by the acid.
EXPERIMENT 80
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P-aminophenol is quickly oxidized by oxygen from air in alkaline solution.
When acidified, the oxidation product becomes much lighter, but the original
compound is not restored again.
EXPERIMENT 81
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Phenidone is oxidized by air, but is much less susceptible to oxidation
than developers, such as hydroquinone, pyrogallol.
EXPERIMENT 82
---------------
Benzotriazole is not oxidized by air. Apparently it forms a coordination
complex with chromium (III).
EXPERIMENT 83
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The coordination complexes formed by iron-salts and phenol-like photographic
developers show very typical reactions with hydrogen peroxide. Many times
these reactions result in oxidation products which are not dark colored,
as opposed for oxidation by atmospheric oxygen.
EXPERIMENT 84
---------------
When p-aminophenol is oxidized in an acidic environment, then a compound
is formed, with a deep indigo/purple color.
EXPERIMENT 85
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When p-aminophenol is oxidized in acidic environment, then an intensely
colored compound is formed (indigo/purple). This compound is irreversibly
destroyed when the liquid is made alkaline.
EXPERIMENT 86
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When p-aminophenol is oxidized by hypochlorous acid, then an other oxidation
product is formed, compared to oxidation by e.g. persulfate, hydrogen
peroxide etc. When oxidized by hypochlorous acid a yellow solid compound
is formed, otherwise an intense indigo/purple compound is formed, which
remains dissolved.
EXPERIMENT 87
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P-aminophenol HCl reacts with bromine and forms a purple compound.
EXPERIMENT 88
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When hydroquinone is oxidized by hydrogen peroxide in acidic environments,
then a pale yellow compound is formed. This is in strong contrast with
oxidation by oxygen from air in alkaline environment, where a dark brown/
black compound is formed.
EXPERIMENT 89
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P-aminophenol, when oxidized, forms a deeply colored compound. The color
of this compound is deep blue/purple, but the environment and the used
oxidizer have some influence on the color of the liquid as a whole (other
compounds may make the color less pure).
EXPERIMENT 90
---------------
Potassium chlorate is able to liberate bromine from a bromide. Reaction
with sodium sulfide of the bromine shows formation of fumes/smoke.
EXPERIMENT 91
---------------
Potassium chlorate only reacts slowly with iodide at room temperature.
When heated, the reaction proceeds much faster. Probably KClO3 oxidizes
iodine further, until iodate is formed.
EXPERIMENT 92
---------------
Bromide is oxidized by hydrogen peroxide in acidic environments. Addition
of nitric acid strongly enhances the reaction.
EXPERIMENT 93
---------------
Chlorine reacts with acetylene gas (C2H2), without the need to ignite it.
EXPERIMENT 94
---------------
Sodium chlorate reacts with chloride in acidic environment, forming chlorine
(which can be detected by means of its odour) and a fairly intensely colored
yellow gas (chlorine dioxide). The color of this gas is much more intense
than the color of chlorine.
The yellow compound is destroyed by sulfite and nitrite.
EXPERIMENT 95
---------------
Potassium bromate reacts vigorously with concentrated hydrochloric acid.
A green gas is evolved, but this gas has a color, which is fairly intense.
The green gas consists of chlorine, but it also contains bromine, probably
combined with chlorine in a compound as BrCl, which is slightly darker
green than Cl2.
EXPERIMENT 96
---------------
Although the redox potential from bromate to bromine is higher than the
potential from perchlorate to chlorate, when chlorate and bromate are
mixed, then no reaction occurs. When some hydrochloric acid is added,
then a reaction occurs with the chloride ions.
EXPERIMENT 97
---------------
Chlorate and bromate react with hydrochloric acid, but bromate reacts more
vigorously. There also is a marked difference between potassium and sodium
chlorate. The sodium salt reacts more vigorous with hydrochloric acid, but
not as vigorous as potassium bromate.
Reactions of bromate are faster than reactions of chlorate, but for sodium
and potassium chlorate, the difference can be explained by the speed at
which the salt dissolves.
EXPERIMENT 98
---------------
A mixture of chlorine and chlorine dioxide oxidizes bromide quickly to
bromine. When an excess amount of nitrite is added, then the bromine is
quickly reduced again to bromide. Addition of an acid does not result in
formation of bromine again.
EXPERIMENT 99
---------------
Bromate reacts with chlorides, releasing chlorine. Probably some bromine
is produced as well or a bromine/chlorine compound is produced.
EXPERIMENT 100
---------------
Lithium fluoride is only sparingly soluble.
EXPERIMENT 101
---------------
Both iodate and periodate form the tetrachloroiodide ion in a strong
solution of hydrochloric acid. A redox reaction occurs, where the iodine
is reduced to its +3 oxidation state and chlorine is released.
EXPERIMENT 102
---------------
Tungstate ions, when reduced, produce a deep blue color. Tungstate is
a weak oxidizer.
EXPERIMENT 103
---------------
Cadmium selenide reacts vigorously with nitric acid, producing nitrous
fumes and a yellow/orange solid, which is filled with many small gas bubbles
and hence remains floating on the liquid.
Cadmium sulfide gives a similar reaction, but now a pale yellow solid is
formed. This yellow solid is sulphur.
EXPERIMENT 104
---------------
Selenium dissolves in a sulfide solution, forming a deep red/brown solution.
Hydrogen peroxide is capable of oxidizing this solution.
EXPERIMENT 105
---------------
Magnesium dissolves in acid very easily.
EXPERIMENT 106
---------------
Rhenium is oxidized easily by nitric acid. The oxidation product is a color-
less compound, soluble in water (according to literature it is perrhenic
acid, HReO4). Perrhenic acid is not a really strong oxidizer. It can be
reduced by zinc, but addition of sodium sulfite does not result in formation
of the same compound.
Hydrogen peroxide is capable of oxidizing back to perrhenic acid, but some
light yellow compound remains. What is it?
EXPERIMENT 107
---------------
Rhenium, when dissolved in nitric acid, gives colorless perrhenate ions,
[ReO4]-. With zinc, in the presence of hydrochloric acid of sufficient
concentration, this can be reduced to a yellow/green species. With cyanide,
in alkaline environment this forms a brown and clear solution. The yellow/
green species may be [ReCl6]2-, which according to literature is green.
With cyanide, a complex may be formed.
EXPERIMENT 108
---------------
Rhenium can be oxidized to colorless perrhenate [ReO4]-, with nitric acid.
With zinc it can be reduced to a yellow/green species in the presence of
hydrochloric acid at sufficient concentration. This species apparently is
not reduced any further with borohydride in alkaline environments. In
acidic environments, a dark brown/black compound can be formed easily,
due to reduction of thiosulfate to sulfide by the borohydride. The sulfide
forms a dark compound with rhenium.
With sulfite, perrhenate nor the yellow/green compound can be reduced to
a lower oxidation state.
EXPERIMENT 109
---------------
Cadmium ions give a precipitate with sulfide at very low concentration
of free sulfide ions. Only at very low pH, cadmium ions and hydrogen
sulfide can coexist in solution at appreciable concentration.
A very similar effect can be seen with combinations of cadmium and
selenide.
EXPERIMENT 110
---------------
Praseodymium chloride dissolves in water very well and very easily, but it
hydrolyses. A solution of this is turbid. When the solution is slightly
acidified, then a very pale green and clear solution is obtained.
Praseodymium chloride only dissolves slowly in concentrated hydrochloric acid.
The solution also has another color than a plain slightly acidified solution.
The solution in concentrated hydrochloric acid is yellow and its color is much
more intense than the pale green color of aqueous praseodymium ions.
EXPERIMENT 111
---------------
This is a set of experiments, demonstrating an interesting aspect of thallium
chemistry, in combination with different iodine-containing compounds.
EXPERIMENT 112
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Chromium (III) has many different colors, depending on coordinated ligands.
EXPERIMENT 113
---------------
Chromium (III) can be converted to chromium (VI) in strongly alkaline
environments.
EXPERIMENT 114
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Oxidation of chromium (III) to chromium (VI).
EXPERIMENT 115
---------------
When Cr3+ is added to an aqueous solution of ammonia, then a precipitate
is created, which does not dissolve on addition of much more ammonia.
EXPERIMENT 116
---------------
Cr(III) can be reduced to Cr(II) by a zinc nail. On reoxidation to Cr(III)
a coordination complex appears to be created, both with sulfate and with
chloride.
EXPERIMENT 117
---------------
Chromium (III) can have many different colors, depending on how it is
created and with which it coordinates.
EXPERIMENT 118
---------------
Chromium (III) can be oxidized to chromium (VI) by persulfate in alkaline
environments.
EXPERIMENT 119
---------------
The color of chromium (III) depends on how it is part of coordination
complexes.
EXPERIMENT 120
---------------
Bleach is capable of oxidizing chromium (III) to its hexavalent state, but
this is not accomplished easily and completely.
EXPERIMENT 121
---------------
EDTA builds pink complexes with chromium (III). This complex is destroyed
in strongly alkaline environments.
EXPERIMENT 122
---------------
Basic chromium (VI), chromate, is not capable of oxidizing ascorbate. On
acidification, immediate oxidation occurs and a coordination complex is
formed.
EXPERIMENT 123
---------------
When chromium (III) is created from dichromate, its color depends on the
reductor used and on the acid which is used for supporting the redox
reaction.
EXPERIMENT 124
---------------
Chromium (III) apparently builds a coordination complex with hydroxyl amine,
but this complex does not simply form from chromium (III) salts and
hydroxyl amine. If chromium (III) is formed by means of reduction of
chromium (VI) in the presence of hydroxyl amine, then the complex is
formed. If hydroxyl amine is added to chromium (III) without redox reaction,
then another complex is created.
EXPERIMENT 125
---------------
Tetraperoxochromate does not dissolve well in water and is not stable.
In acidic environments it cannot exist at all. It decomposes, yielding a
large amount of oxygen. It is not capable of oxidizing hydrochloric acid
to chlorine, it simply decomposes, giving off all its oxidizing power
in the form of oxygen.
EXPERIMENT 126
---------------
Dichromate can be reduced by hydrochloric acid with some difficulty.
EXPERIMENT 127
---------------
Dichromate reacts with hydrogen peroxide, also when no acid is present.
An initial compound is formed quickly, which decomposes slowly, releasing
heat. Due to heating up, the reaction proceeds faster and faster, until
all of the peroxide has been used up.
EXPERIMENT 128
---------------
Chromic acid reacts with hydrogen peroxide under formation of a dark blue
compound. When more hydrogen peroxide is added, then apparently the pH of
the liquid becomes too high and other almost black compounds are formed,
which quickly decompose.
EXPERIMENT 129
---------------
Chromium (III) forms a purple coordination complex with nitrite. This
complex has a fairly bright pink/purple color, which differs quite a lot
from the color of aqueous chromium (III).
EXPERIMENT 130
---------------
Neodymium ions form a yellow/lime green precipitate with chromate ion.
The solubility of neodymium chromate is very low.
Neodymium dichromate is much more soluble, at least in acidic solution.
EXPERIMENT 131
---------------
It is not possible to make methylammonium chromate or methylammonium
dichromate by mixing solutions of CrO3 and CH3NH2 in water and letting
the solution evaporate. Apparently, chromic acid is not sufficiently
acidic in aqueous solution to protonate the methylamine to a salt.
This is in strong contract with perchloric acid, which, when mixed
with excess methylamine, gives a nice dry solid CH3NH3ClO4 on evaporation.
This also is in strong contrast with ammonia, which gives a mix of
(NH4)2CrO4 and (NH4)2Cr2O7 when excess ammonia and CrO3 are mixed and
allowed to evaporate to dryness.
EXPERIMENT 132
---------------
Persulfate is not capable of oxidizing manganese to the (VII) state
in acidic environments.
EXPERIMENT 133
---------------
Permanganate is capable of oxidizing thiocyanate in acidic environments:
The result is a pink solution, more intensely colored than manganese (II)
ions (which are almost colorless).
EXPERIMENT 134
---------------
When solid potassium permanganate is added to concentrated hydrochloric
acid, then a gas is evolved, being chlorine. The liquid becomes almost
black. When the reaction is driven to an end by heating (almost boiling)
the liquid, then the final liquid does not become colorless, but green.
The green color is not a bright green, but it is brownish/sepia-like.
What is the constitution of this green/sepia compound?
A similar observation is done when hydrochloric acid is heated with
manganese dioxide. In the cold there is no visible reaction, but when
heated, chlorine is produced and a green compound is formed.
EXPERIMENT 135
---------------
Manganese (II) forms a white precipitate with bicarbonate, while slowly
developing a gas (probably this is CO2). This precipitate is not quickly
oxidized by oxygen from the air. When the precipitate is made more alkaline
by adding hydroxide, then it is oxidized fairly quickly. Addition of
hydrogen peroxide causes immediate oxidation of the alkaline precipitate.
EXPERIMENT 136
---------------
Antimony (III) is oxidized by dichromate in acidic environments.
EXPERIMENT 137
---------------
Antimony (III) is supposed to form a stable complex with tartaric acid or
tartrates. This experiment does not show such behaviour. Apparently the
conditions must be selected carefully in order to create the antimony/
tartrate complex.
EXPERIMENT 138
---------------
Sulfide is capable of forming a brightly coloured compound with antimony
(III) in a strongly acidic environment. The sulfide is not destroyed by
strong acid and is not converted to hydrogen sulfide gas.
EXPERIMENT 139
---------------
Sulfide is capable of dissolving sulphur, forming intensely colored poly-
sulfide species. These poly-sulphide species react with antimony (III) in
strongly acidic environments, resulting in two different types of
precipitates.
EXPERIMENT 140
---------------
Elementary antimony dissolves in aqua regia at a fairly high rate. While
it dissolves a lot of gas is produced. When the liquid is diluted with
water, then a white precipitate is formed, due to hydrolysis of the
reaction product. It looks as if the antimony is oxidized to the +3 oxidation
state.
EXPERIMENT 141
---------------
Tin (II) compounds forms either a yellow or orange/red compound with
iodides. What compound is formed, depends on the concentration of the
reactants.
At very low pH such a compound is not formed anymore, and once formed,
it can be dissolved.
EXPERIMENT 142
---------------
Dichromate is quickly reduced by tin (II) ions.
Hydrogen peroxide does not show a visible reaction with tin (II) ions.
EXPERIMENT 143
---------------
Tin metal does not dissolve quickly in concentrated hydrochloric acid.
Tin metal only slowly dissolves in aqua regia.
The solution obtained is clear.
EXPERIMENT 144
---------------
Silver is coordinated by thiosulfate. The silver-thiosulfate complex does
not show any of the reactions of free aqueous silver (I).
EXPERIMENT 145
---------------
Acetone reacts with sulphur in strongly alkaline environments. What products
are formed?
A similar reaction is observed between methyl ethyl ketone and sulphur.
EXPERIMENT 146
---------------
Ascorbic acid is oxidized in a strongly alkaline environment, probably by
oxygen from the air. The oxidation product can be oxidized further, but
this only occurs slowly, compared to the speed with which fresh ascorbic
acid can be oxidized.
EXPERIMENT 147
---------------
Potassium bromate does not react with concentrated formic acid, but when
some bromide or hydrochloric acid is added, then the reaction proceeds
quickly, carbon dioxide being produced.
EXPERIMENT 148
---------------
Tetraethyl ammonium ion does not form a sparingly soluble salt with bromate
ion.
The tetraethyl ammonium ion forms an oily compound, when treated with
bromate and hydrochloric acid. The halogen, released in that reaction
apparently forms a liquid organic, insoluble in water, or is a liquid
ionic compound formed, some tetraethyl ammonium polyhalogenide compound???
There is evidence for the latter (see experiment detailed description).
EXPERIMENT 149
---------------
Ferrous sulfide is a black precipitate, which easily dissolves in acid.
EXPERIMENT 150
---------------
Iron (III) gives a precipitate with S2-, but a redox reaction, resulting
in the formation of sulphur also appears to occur.
EXPERIMENT 151
---------------
Thiosulfate gives a purple coordination complex with iron (III). This
complex, however, is not stable. With iron (II) no complex is formed.
Iron (III) is reduced by thiosulfate after the initial formation of
the purple coordination complex. This is shown by adding ferrocyanide,
which does not result in formation of an intense dark blue precipitate.
EXPERIMENT 152
---------------
Both ferrocyanide and ferricyanide react with zinc salts, yielding
completely differently colored solid compounds.
EXPERIMENT 153
---------------
Ferricyanide gives a dark brown coordination complex with ferric ions. This
complex is soluble in water. It is easily transformed to the much more
stable, dark blue and insoluble ferroferricyanide.
EXPERIMENT 154
---------------
Ferrous ions give a yellow coordination complex with oxalate. The normal
color of ferrous ions is pale green. Ferric ions give a green coordination
complex with oxalate. The normal color of ferric ions is yellow/brown.
The ferric complex is only formed if the environment is not too acidic.
EXPERIMENT 155
---------------
The experiment described below suggests the formation of a coordination
complex between iron and ascorbate. The presence of the ascorbate induces
a completely different behavior of ferric/ferrous ions in alkaline
environments.
EXPERIMENT 156
---------------
Ferric ions apparently form a coordination complex with glucose in alkaline
environments. Normally ferric ions give a brown precipitate in strong
alkaline liquids, with glucose the liquid remains clear.
EXPERIMENT 157
---------------
Ferric ions form a coordination complex with sulfite.
EXPERIMENT 158
---------------
Phenol and its derivatives form highly colored coordination complexes
with ferrous and ferric ions.
EXPERIMENT 159
---------------
When concentrated hydrochloric acid is added to a concentrated solution of
potassium ferrocyanide, then a white precipitate is formed (probably this
is KCl). The liquid slowly turns blue, but this is not due to formation
of the well known prussian blue or a similar compound.
EXPERIMENT 160
---------------
Dithionite is not capable of reducing ferric oxide/hydroxide to an iron (II)
compound in alkaline environments.
EXPERIMENT 161
---------------
Dithionite reduces ferric ions to ferrous ions quickly in acidic
environments.
EXPERIMENT 162
---------------
Ferrocyanide and ferricyanide react with hydroxyl amine in an unexpected way.
The ferri complex first decolorizes, but then a new colored compound is
formed. The ferro complex shows this behaviour immediately.
EXPERIMENT 163
---------------
When ferric sulfate is dissolved in water, then an almost colorless liquid
is formed. On addition of chloride, a coordination complex (brown/yellow)
is formed.
EXPERIMENT 164
---------------
When an acidified solution of ferric chloride is mixed with a solution
of hydroxyl amine sulfate, then an almost colorless compound is formed,
but this compound does not seem to be an iron (II) compound.
EXPERIMENT 165
---------------
Hydroxyl amine reacts with ferrocyanides, forming a dark compound. Is the
ferrocyanide oxidized by the hydroxyl amine? This reaction occurs in
neutral environments, with the hydroxyl amine bound in a hydroxyl ammonium
salt.
EXPERIMENT 166
---------------
Iron (III) builds a coordination complex with phosphates.
EXPERIMENT 167
---------------
Ferric oxide (Fe2O3, dark red/brown) dissolves in hydrochloric acid and
nitric acid, but with extreme difficulty and in very small quantities.
EXPERIMENT 168
---------------
Ferric ions form a colorless complex with phosphate ions in acidic
environments. In the presence of chloride ions, a yellow coordination
complex is formed, which can exist, even in the presence of phosphate.
EXPERIMENT 169
---------------
Ferric ions are reduced by borohydride to a black compound. Is this
metallic iron or is this iron (II) oxide?
EXPERIMENT 170
---------------
Iron does not dissolve quickly in dilute hydrochloric acid. When some sodium
fluoride is added, then it still does not dissolve quickly. This is in strong
contrast with titanium metal, which does dissolve quickly in dilute HCl,
when some HF is present.
EXPERIMENT 171
---------------
Catechol appears to react with nickel (II), giving a coordination complex.
It is unclear, whether this is due to catechol itself or due to an
oxidation product, caused by oxidation by oxygen from air.
EXPERIMENT 172
---------------
This experiment describes a qualitative method, useful for showing the
presence of minute quantities of manganese (II), which cannot be detected
by oxidation with H2O2 in alkaline environments anymore. Chloride ions
may not be present besides the manganese to be detected.
EXPERIMENT 173
---------------
Nickel in nickel (II) hydroxide is oxidized to a higher oxidation state by
hypochlorites, but not by chlorates. The oxidation product is reduced by
hydrogen peroxide and ammonia. Heating of the oxidation product makes it
more resistant to reduction and to breakdown by acids.
EXPERIMENT 174
---------------
Borohydride is capable of reducing nickel to the metallic state in
aqueous media.
EXPERIMENT 175
---------------
Titanium metal slowly dissolves in concentrated hydrochloric acid and then
forms a very dark solution of a titanium/chloride complex. This solution is
much darker than an aqueous solution of titanium(III) in which the ions are
present as aqua complex.
With thiocyanate an even more intensely colored complex is formed. This complex
has the same color, but it is very dark.
EXPERIMENT 176
---------------
When compounds of manganese(IV) or manganese(VII) are added to hydrochloric
acid, then chlorine gas is produced and the solution becomes very dark
brown/green. Only after a long time of heating, all dark brown/green material
is gone and what remains is a pale solution, containing manganese(II) ions.
In this series of experiments it was attempted to go the other way around. Is
it possible to go from almost colorless manganese(II) to the dark colored
compounds of manganese(III) or manganese(IV). This was done by adding chlorine
to solutions of manganese(II) salts in concentrated hydrochloric acid.
While doing so, an interesting observation was made. The dark colored compound
indeed can be made from manganese(II) in concentrated hydrochloric acid, but
only from hypochlorite and not from chlorine.
When calciumhypochlorite is added to hydrochloric acid, then chlorine is formed
vigorously, and the solution becomes green and clear.
It seems, however, that even in concentrated hydrochloric acid some of the
hypochlorite is not decomposed at once, but remains in solution as yellow/green
hypochlorous acid.
A freshly prepared solution, made from a pinch of calcium hypochlorite and
concentrated hydrochloric acid, reacts differently than a saturated solution of
chlorine in concentrated hydrochloric acid. This is shown with manganese(II)
ions in hydrochloric acid.
EXPERIMENT 177
---------------
Ethylene diamine (NH2CH2CH2NH2) and iodic acid form a moderately soluble salt.
In the dry state, this salt is fairly stable. Only when it is heated strongly,
it decomposes with a soft puff, giving a yellow/brown smoke and a bad smell.
EXPERIMENT 178
---------------
Vanadium pentoxide does not seem to react with red phosphorus.
EXPERIMENT 179
---------------
Sodium selenite dissolves in concentrated hydrobromic acid with a red/brown
color. When this solution is shaken with ligroin, then the ligroin layer also
turns red/brown. The compound, dissolved in the ligroin layer is a selenium
compound, as is demonstrated by the experiment, described in more detail below.
EXPERIMENT 180
---------------
Copper(II) can be reduced to the very peculiar compound CuH by hypophosphorous
acid, but only under very specific conditions. The compound CuH is quite
unstable and easily looses hydrogen.
In the presence of chloride ions, no CuH is formed, but CuCl is formed instead.
EXPERIMENT 181
---------------
Tert-butanol is very easily converted to tert-butyl chloride. Simply adding
tert-butanol to concentrated hydrochloric acid allows the formation of this
compound.
EXPERIMENT 182
---------------
Cesium forms a solid red/brown chloro complex of copper(II). This complex is
very remarkable, due to its rust-like color, which is very uncommon for
copper(II) salts.
EXPERIMENT 183
---------------
Finely divided magnesium powder violently reacts with wet cupric nitrate and
with wet ferric nitrate. The dry solids do not react.
EXPERIMENT 184
---------------
Niobium pentachloride reacts with acetic acid, giving a colorless fuming gas
(most likely HCl) and a fuming liquid (most likely acetyl chloride).
EXPERIMENT 185
---------------
Copper(II) oxide slowly dissolves in a highly concentrated solution of citric
acid and after a while a brightly colored crystalline solid is formed, which
most likely is copper(II)citrate.
EXPERIMENT 186
---------------
Niobium pentachloride reacts violently with water, releasing hydrogen chloride.
Niobium pentachloride also reacts vigorously with hydrochloric acid. The liquid
first remains clear, but on standing it becomes turbid.
When zinc is added, then a deep blue compound is formed, which on dilution
becomes brown, and finally becomes colorless and turbid.
EXPERIMENT 187
---------------
When antimony is added to liquid bromine, then a violent reaction occurs, even
with appearance of sparks.
EXPERIMENT 188
---------------
When copper ions are brought in contact with periodate, then a yellow/green
precipitate is formed. This precipitate very easily dissolves in hydrochloric
acid, giving chlorine gas and other products.
When the same is done with manganese(II) ions instead of copper ions, then a
brick-red precipitate is formed, which does not easily dissolve in hydrochloric
acid.
EXPERIMENT 189
---------------
Antimony trioxide dissolves in hydrochloric acid, giving a colorless solution.
When hydrogen sulfide is passed through such a solution, then a small amount of
a yellow precipitate is formed and the liquid becomes very pale yellow.
On dilution, much more precipitate is formed and the surprisingly, the color
shifts from pale yellow to orange. The orange solid must be hydrous Sb2S3.
EXPERIMENT 190
---------------
Iodine does not react with nitrite in methanolic solution.
Iodine does react with hydroxide in methanolic solution, a very light yellow
compound is formed. On acidification this gives iodine again.
Iodine does react with red phosphorous in methanolic solution, but the reaction
is slow.
EXPERIMENT 191
---------------
Rhenium forms complexes with thiocyanate in more than one oxidation state.
Here a rhenium (IV) thiocyanate complex is made and then oxidized to rhenium
(V). Historically these complexes have been used to detect minute traces of
rhenium due to the intense colours formed.
EXPERIMENT 192
---------------
When concentrated hydrochloric acid is added to solid NaClO2, then a lot of
intense yellow ClO2 is produced, but normally the gas does not explode.
When concentrated hydrochloric acid is added to a mix of solid NaClO2 and solid
NaBrO3, then a yellow gas is produced and within a few seconds at most, the gas
explodes, the explosion starting at/near the liquid surface.
EXPERIMENT 193
---------------
When sodium chlorite solution is acidified with acetic acid, then a brown
solution is obtained, which on addition of more acetic acid becomes lighter and
which on addition of hydrochloric acid becomes bright yellow.
EXPERIMENT 194
---------------
When a solution of manganese(II)chloride in moderately concentrated
hydrochloric acid is electrolysed, then at the anode a remarkable very dark
compound is formed. The liquid remains clear, but it becomes very dark. This
must be a compound of manganese in higher than +2 oxidation state.
When a similar experiment is performed with manganese(II)sulfate in a 20%
solution of sulphuric acid, then a drk brown precipitate is formed at the
anode.
EXPERIMENT 195
---------------
Arsenate does not form thioarsenates when sulfide ion is added. On
acidification, the sulfide is oxidized though by the arsenate.
EXPERIMENT 196
---------------
Arsenate ion and arsenic acid cannot easily be reduced to the element.
Reduction to trivalent arsenic, however, can easily be accomplished with
iodide.
EXPERIMENT 197
---------------
Calcium iodate is very sparingly soluble in water, but it can form strongly
oversaturated solutions and may take a long time to crystallize.
Calcium iodate also is quite stable, it must be heated strongly in order to
decompose it.
EXPERIMENT 198
---------------
Chromium trioxide (CrO3) dissolves in concentrated hydrochloric acid, giving a
dark brown liquid. When this liquid is heated, then some orange/brown chromyl
chloride is formed, which can easily be observed as a vapor above the liquid.
On further heating the hydrochloric acid is oxidized and the hexavalent
chromium is converted to green trivalent chromium.
EXPERIMENT 199
---------------
Dichromate ion oxidizes thiosulfate easily in acidic media, but in neutral
media it only is oxidizing incompletely, and a solid compound is formed.
EXPERIMENT 200
---------------
This experiment nicely demonstrates the effect of light on a chemical compound.
An alkaline solution of potassium fericyanide (K3Fe(CN)6) is stable in the
dark, but in sunlight it decomposes in a few hours.
EXPERIMENT 201
---------------
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 202
---------------
Hydrogen chloride does not dissolve very well in concentrated perchloric acid.
EXPERIMENT 203
---------------
Cesium ion allows many very special complexes to be isolated as solid salts. In
this experiment it is demonstrated how this is done for selenium and tellurium
complexes.
EXPERIMENT 204
---------------
Arsenic in oxidation state +5 is not easily reduced to elemental arsenic,
except by tin(II) chloride.
EXPERIMENT 205
---------------
Ferric chloride anhydrous easily melts and when it melts, it also nearly boils
and a dark yellow/brown vapor is formed, which condenses to beautiful crystals
in cooler areas.
A small part of the ferric chloride reacts either with oxygen from the air, or
with water vapor in the air. Insoluble oxide-species are formed.
EXPERIMENT 206
---------------
Titanium(III) ions are fairly stable in acidic media, but in alkaline solution,
these become so strongly reducing that hydrogen gas is formed and water is
reduced!
EXPERIMENT 207
---------------
Chromium metal does not dissolve al all in concentrated nitric acid, not even
when the acid is heated. It does dissolve in concentrated hydrochloric acid and
also in moderately concentrated perchloric acid, but in the latter some heating
is required.
EXPERIMENT 208
---------------
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.
EXPERIMENT 209
---------------
Praseodymium ions form a very light green precipitate with periodate, which
almost completely dissolves on heating.
EXPERIMENT 210
---------------
White phosphorus reacts with hot solutions of sodium hydroxide and gaseous
phosphine and diphosphine are produced. The diphosphine spontaneously combusts
in air, the phosphine does not. The diphosphine is very unstable and within a
few minutes it reacts and only phosphine is left.
REMARK: THIS IS A VERY DANGEROUS EXPERIMENT. WHEN NOT CARRIED OUT WITH
SUFFICIENT PRECAUTIONS. KNOW WHAT YOU ARE DOING!!
EXPERIMENT 211
---------------
When anhydrous sodium formiate is heated, then it first melts and on further
heating it decomposes, giving a colorless gas. This colorless gas is highly
flammable and forms explosive mixes with air.
EXPERIMENT 212
---------------
Antimony trioxide does not dissolve in concentrated nitric acid, not even when
the liquid is heated to boiling. When some hydrochloric acid is added as well,
then it quickly dissolves, producing a colorless gas as well. It is oxidized to
the +5 oxidation state.
When this solution is diluted, then a white precipitate is formed. This white
precipitate must be hydrous Sb2O5. When a dilute solution of sodium sulfide is
added to this still strongly acidic solution, then H2S bubbles out of solution,
but also a lot of precipitate is formed, which has a beautiful bright
orange/red color.
EXPERIMENT 213
---------------
This is a spectacular experiment. A mix of sodium chlorite and red phosphorus
can be ignited by bringing it in contact with hydrochloric acid.
EXPERIMENT 214
---------------
Arsenic in oxidation state +3 is quickly reduced to elemental arsenic by
tin(II) chloride in hydrochloric acid.
EXPERIMENT 215
---------------
Copper(II) ions form a pale green complex with a yellowish hue. When the
solution is heated to boiling, then the copper(II) is reduced to metallic
copper.
EXPERIMENT 216
---------------
A clock reaction that precipitates antimony sulfide.
End of results for 'hydrochloric acid'