Experiments for 'sodium hydroxide'
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 'sodium hydroxide':
EXPERIMENT 1
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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 2
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Cobalt gives a green coordination complex with tartrates, when oxidized to
the +3 state.
EXPERIMENT 3
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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 4
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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 5
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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 6
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Mercury (II) ions produce a bright orange colored precipitate with iodide.
EXPERIMENT 7
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Mercury (II) salts give an oxide/hydroxide, which does not dissolve in
large excess amounts of alkaline solutions. Ammonia does not dissolve
the precipitate of mercury (II) oxide/hydroxide.
EXPERIMENT 8
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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 9
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The blue precipitate, formed when ferrocyanide and ferric ions act
upon each other is not stable in alkaline environments.
EXPERIMENT 10
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Bleach is not capable of oxidizing ferric hydroxide to the hexavalent
ferrate (at least not at 60 C within several minutes).
EXPERIMENT 11
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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 12
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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 13
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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 14
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Ferric ions form coordination complexes with citrates and oxalates. These
coordination complex have completely different properties than free
ferric ions.
EXPERIMENT 15
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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 16
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Dithionite is not capable of reducing ferric oxide/hydroxide to an iron (II)
compound in alkaline environments.
EXPERIMENT 17
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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 18
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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 19
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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 20
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Potassium ferrocyanide reacts with concentrated nitric acid. The compound
which is formed is dark brown/green. What is this compound?
Is the dark brown/green color due to formation of a Fe(NO)+ complex, well
known from the brown-ring test for nitrates?
EXPERIMENT 21
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Iron (III) builds a coordination complex with phosphates.
EXPERIMENT 22
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Ferrocyanide in acidic environments reacts with bromine in a very peculiar
way. An extremely dark compound is formed. This reaction does not occur
in neutral environments and this cannot be observed with ferricyanides.
What is the dark compound? Is it a coordination complex or a condensation
product of many ferric/ferrous ions, close to formation of solid particles?
EXPERIMENT 23
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Ferrous ions react with hydroxide, forming a light bluish/grey precipitate.
This precipitate, however, quickly turns brown.
EXPERIMENT 24
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Hydroxylamine is capable of reducing ferricyanide to ferrocyanide. On heating,
however, a yellow compound is formed, which apparently is not ferricyanide.
With thiocyanate a pale rose-purple solution is formed on standing. Probably
oxygen from the air also takes part in the reaction.
EXPERIMENT 25
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Persulfate is not capable of oxidizing manganese to the (VII) state
in acidic environments.
EXPERIMENT 26
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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 27
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Manganese (II) ions apparently do not form coordination complexes with EDTA.
If they do so, then the coordination complex is (almost) colorless.
EXPERIMENT 28
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Manganese builds a coordination complex with EDTA, which appears to be
pink. What oxidation state does the manganese have with this complex? It
appears to have oxidation state 2, unless EDTA is easily oxidized by
manganese, having a higher oxidation state.
EXPERIMENT 29
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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 30
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Acetone can be mixed with water in any ratio, but when sodium hydroxide
is added, then the liquids are not miscible in any ratio anymore.
Sulphur reacts with acetone in the presence of sodium hydroxide. Sulfide
does not show such a reaction.
EXPERIMENT 31
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Sulphur dissolves in hot solutions of sodium hydroxide and disproportionates
in a way, similar to disproportionating of halogens.
When acetone is added, a peculiar blue/green compound is formed in the
acetone. What is this compound?
EXPERIMENT 32
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This experiment is performed in order to determine, whether iodoform (CHI3)
shows a reaction, similar to chloroform, when treated with acetone in a
strongly alkaline environment. The result of this experiments suggests
that indeed a similar reaction occurs, resulting in the formation of a
compound with a sweetish mint-like odour.
EXPERIMENT 33
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Acetone reacts with sulphur in strongly alkaline environments. What products
are formed?
A similar reaction is observed between methyl ethyl ketone and sulphur.
EXPERIMENT 34
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MEK can be oxidized by potassium permanganate in alkaline environments (or
is this due to some impurities in the MEK?).
EXPERIMENT 35
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Trichloro ethene reacts with acetone, forming a brown substance, but only
when in a strongly alkaline environment. The exact conditions, under which
this brown substance is formed must be further investigated.
EXPERIMENT 36
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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 37
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Thymol reacts with chloroform and/or sodium hydroxide when heated. A yellow/
green compound is formed. What is this compound?
EXPERIMENT 38
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Tungstate ions, when reduced, produce a deep blue color. Tungstate is
a weak oxidizer.
EXPERIMENT 39
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Lead builds a yellow precipitate with hydroxide and peroxosulfate. This
probably is an oxidation product of lead (II).
EXPERIMENT 40
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Lead hydroxide is oxidized by hydrogen peroxide. The resulting compound
does not dissolve in dilute nitric acid.
EXPERIMENT 41
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Lead (II) salts give a yellow precipitate of lead chromate with dichromates.
When this precipitate is made alkaline, then it turns orange.
EXPERIMENT 42
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Silver (I) is not reduced by hydroxyl amine in neutral environments. When
made alkaline, it is reduced to metallic silver immediately.
EXPERIMENT 43
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Silver chloride and silver oxide dissolve in a solution of sodium
thiosulfate. The reaction is not very fast.
EXPERIMENT 44
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Silver (I) ions form a precipitate, both with ferrocyanide and with
ferricyanide. The precipitate with ferricyanide is decomposed by alkalies,
the precipitate with ferrocyanide is more stable. Both compounds are
attacked by thiosulfate, which complexes the silver and causes the
solid to dissolve again.
EXPERIMENT 45
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Silver salts give a yellow precipitate with silicates. This precipitate
becomes white on addition of sulphuric acid. When a large quantity of
sodium hydroxide is added, then a dark, almost black, solid is created.
EXPERIMENT 46
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Silver (I) ions, when treated with hydroxide give brown silver (I) oxide.
When hydrogen peroxide is added, then that is decomposed and the precipitate
of oxide does not change noticeably. When, however, hydrogen peroxide is
first mixed with a solution of a silver (I) salt and then the hydroxide is
added, then a black precipitate is formed. Probably this is finely divided
metallic silver.
EXPERIMENT 47
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Vitamin C is a strong reductor in alkaline environments. Copper (II) is
reduced to copper (I).
EXPERIMENT 48
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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 49
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Copper hydroxide is not capable of oxidizing methanol.
EXPERIMENT 50
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Formaldehyde is not capable of reducing Fehlings reagent within a few
minutes at temperatures of appr. 60 C.
EXPERIMENT 51
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Metol is capable of reducing copper (II) to copper (I) in alkaline
environments.
EXPERIMENT 52
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Copper (II) builds a coordination complex with glucose in alkaline
environments. On heating, the glucose is oxidized by the copper (II)
and orange/red Cu2O precipitates.
EXPERIMENT 53
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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 54
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Copper (II) gives a coordination complex with ascorbic acid in neutral or
slightly acidic environments. In alkaline environments copper (II) is
reduced rapidly by ascorbic acid / ascorbate.
EXPERIMENT 55
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Copper builds a complex with urea, which has a pale purple color (or is
this due to contamination of the urea with traces of biuret?). The copper,
bound to urea, does not build the intense blue cuprammine complex with
ammonia.
EXPERIMENT 56
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EDTA builds a coordination complex with copper (II). This complex has a
color, resembling the color of simple hydrated copper (II), but it is
much more intense and it has a slightly more cyan-like color.
This complex is not stable in strongly alkaline environments.
EXPERIMENT 57
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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 58
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Copper builds higher oxides than CuO when strong oxidizing agents are
present in alkaline environments. Probably these are not copper (III)
compounds, but the oxo-ion probably is replaced by peroxo or superoxo.
EXPERIMENT 59
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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 60
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In alkaline environments, copper (II) shows remarkable behavior, when brought
in contact with strong oxidizers or reductors.
EXPERIMENT 61
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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 62
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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 63
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Copper (II) does not form a coordination complex with phosphates and/or
phosphoric acid.
EXPERIMENT 64
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Copper (II) is reduced by hydroxyl amine very quickly in alkaline
environments. Yellow copper (I) hydroxide/oxide is formed.
EXPERIMENT 65
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Copper (II) forms a coordination compound with ethyl acetate, which has
reacted with hydroxyl amine.
EXPERIMENT 66
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Copper hydroxide easily looses water, when it is heated, even if it is
completely covered with water.
EXPERIMENT 67
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Persulfate decomposes in strongly alkaline environments.
EXPERIMENT 68
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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 69
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Tannine (a polyphenolic compound of large molecular weight of indeterminate
composition) reacts with many metal ions, forming highly coloured complexes.
It also shows some other reactions. The exact type of reactions is not
always clear.
The tannine, used in these experiments, was brown. It's intended use is
as an additive for making wine.
EXPERIMENT 70
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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 71
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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 72
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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 73
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In strongly alkaline environments, molybdates are not as easily reduced
as in neutral or acidic environments.
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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Molybdenum trioxide dissolves well in strongly alkaline liquids. It does
not dissolve (or just a little bit) in plain water. Once dissolved, it
can be kept in solution, even when pH is lowered.
Molybdates are capable of oxidizing iodide and sulfite.
EXPERIMENT 76
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Molybdate forms strongly colored, but unstable, complexes with hydrogen
peroxide.
EXPERIMENT 77
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Ammonium molybdate forms a yellow coordination complex with phosphates in
acidic environments, which precipitates. Oxidizing compounds do not
dissolve this precipitate, alkaline compounds do dissolve this precipitate.
EXPERIMENT 78
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When molybdate (VI) is reduced by a small amount of reductor, then a blue
compound is formed. When a larger amount of reductor is available, then a
black compound is formed.
EXPERIMENT 79
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Vanadium (V) builds different kinds of poly-vanadates, with colors ranging
from colorless to deep orange/red.
EXPERIMENT 80
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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 81
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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 82
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Hydrogen peroxide builds complexes with vanadium (IV) and vanadium (V)
species. These compounds are not stable and result in dissociation of
the complex and formation of vanadium (IV) compounds. The net result
of adding hydrogen peroxide to a solution containing vanadium (V) can
be reduction to vanadium (IV) with the formation of oxygen.
EXPERIMENT 83
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Vanadium (IV) does not build complexes with EDTA in acidic environments.
EXPERIMENT 84
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Vanadyl builds an intensely colored complex with thiocyanate in acidic
environments. In alkaline environments this complex is destroyed.
When H2O2 is added, this complex is destroyed as well, but in this
case some heating is required.
EXPERIMENT 85
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The vanadyl salt of ferrocyanide does not dissolve in water. The salt is
easily hydrolysed in alkaline environments (it resembles the prussian blue
as far as this behaviour is concerned).
EXPERIMENT 86
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The vanadyl salt of ferricyanide does not dissolve. The differences between
the ferricyanide salt and ferrocyanide salts are not very clear. In alkaline
solution apparently ferricyanide and vanadate (IV) can coexist.
EXPERIMENT 87
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Vanadium (V) compounds can coexist with ferricyanide in solution. Reduction
of either one of them results in formation of a precipitate.
EXPERIMENT 88
---------------
Vanadyl gives diverse complexes with citrate, the color of these complexes
strongly depends on the pH of the solution.
EXPERIMENT 89
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It is possible to let a liquid completely solidify by making the correct
precipitates. Citrate is very suitable for this, combined with some
transition metals.
EXPERIMENT 90
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The result of this experiment is remarkable. Hydroxyl amine, being a strong
reductor, appears to oxidize vanadium (IV) to vanadium (V) in alkaline
environments. Or is there another compound, which strongly resembles the
well-known yellow colour of vanadium (V) in acidic environments and the
(almost) colourless appearance of vanadium (V) in alkaline environments?
EXPERIMENT 91
---------------
Vanadyl ions do not form a special complex with tartaric acid in strongly
acidic environments.
When hydrogen peroxide is added, a complex is formed, but is
this due to the presence of tartaric acid?
When tartaric acid is added to a solution of vanadyl sulfate in an
environment, which is only slightly acidic, then a green complex is
formed. On making the liquid more basic, a vague sequence of color
changes occurs, through grey/blue, finally going to brown.
EXPERIMENT 92
---------------
Vanadium (V) compounds form yellow compouds with hydrogen peroxide in
alkaline environments, with strong solutions and very high alkalinity grey
and blue compounds are formed, which, however, decompose easily.
EXPERIMENT 93
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Vanadium pentoxide can be dissolved in very concentrated solutions of NaOH
in considerable quantities. When such a solution is cooled down, then a
white crystalline solid separates from the liquid and the liquid completely
solidifies.
EXPERIMENT 94
---------------
Vanadyl forms a light blue or white compound with phosphates, when it is
precipitated.
In excess alkali, this dissolves, forming a greenish brown clear liquid.
This color is like the familiar brown color of strongly alkaline solutions,
containing vanadium in the +4 oxidation state, but a little bit less reddish
and more greenish.
EXPERIMENT 95
---------------
Vanadium (V) is capable of forming many peroxo compounds, whose appearance
strongly depends on pH.
EXPERIMENT 96
---------------
Without the help of a strong acid, vanadium pentoxide is not capable of
oxidizing formic acid, not even when heated. When some sulfite is added,
then incomplete reduction of the V2O5 can be observed.
With the help of a strong acid and when in solution, vanadium (V) is
capable of oxidizing formic acid, but only very slowly.
With formic acid and vanadium (IV), apparently a coordination complex
is formed. Another explanation is given below at the end of the
description.
EXPERIMENT 97
---------------
Chromium (III) has many different colors, depending on coordinated ligands.
EXPERIMENT 98
---------------
Chromium (III) can be converted to chromium (VI) in strongly alkaline
environments.
EXPERIMENT 99
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Oxidation of chromium (III) to chromium (VI).
EXPERIMENT 100
---------------
Chromium (III) can be oxidized to chromium (VI) by persulfate in alkaline
environments.
EXPERIMENT 101
---------------
Bleach is capable of oxidizing chromium (III) to its hexavalent state, but
this is not accomplished easily and completely.
EXPERIMENT 102
---------------
EDTA builds pink complexes with chromium (III). This complex is destroyed
in strongly alkaline environments.
EXPERIMENT 103
---------------
Chromium (III) is oxidized to dichromate (chrome (VI)) by persulfate. This
reaction is catalyzed by silver (I).
EXPERIMENT 104
---------------
Basic chromium (VI), chromate, is not capable of oxidizing ascorbate. On
acidification, immediate oxidation occurs and a coordination complex is
formed.
EXPERIMENT 105
---------------
Chromate is reduced by dithionite in strongly alkaline solution, but this
reaction proceeds slowly.
EXPERIMENT 106
---------------
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 107
---------------
When potassium dichromate is reduced by thiourea in acidic environments, then
a moss-green compound of chromium (III) is formed. When already existing
chrome (III) is added to a solution with thiourea, then the moss-green
compound is not formed.
EXPERIMENT 108
---------------
Chromium (III) forms a lavender precipitate, when combined with hydroxyl
amine in alkaline environments. This compound does not dissolve in
strongly alkaline environments.
EXPERIMENT 109
---------------
Chromium (III) cannot be oxidized to chromium (VI) by vanadium (V) species
or bromates in strongly alkaline environments. Peroxodisulfate is capable
of achieving this.
EXPERIMENT 110
---------------
Dichromate is capable of oxidizing tartaric acid and a colorless gas is
formed in this reaction (probably CO2). The liquid becomes purple/grey
(hard to describe color, depending on viewing illuminant).
The reaction product does not form a special complex in alkaline environment,
the familiar green color of chromium (III) in alkaline environments is
created. Addition of glycerol does not result in formation of a special
coordination complex.
When, however, dichromate is reduced by an excess amount of glycerol, then
a special coordinate complex appears to be formed, when the solution is
made alkaline. Even addition of acid does not destroy this complex.
EXPERIMENT 111
---------------
Dichromate reacts with hydrogen peroxide, yielding chromium (III) as the
final product, in acidic environments. In alkaline environments, chromium
(III) yields chromate with hydrogen peroxide.
EXPERIMENT 112
---------------
Dichromate is reduced by sulfite in neutral/slightly alkaline enviromments.
Under these conditions a jelly-like precipitate is formed, which is fairly
stable and does not dissolve immediately in dilute sulphuric acid. This
jelly-like precipitate is a chromium (III) compound.
The compound, however, does dissolve easily in strongly alkaline liquids.
The formation of this compound is not affected by the type of the cation
in the chromium-compound.
EXPERIMENT 113
---------------
Hydroxyl amine gives a brown coordination complex when it reduces hexavalent
chromium to trivalent chromium in alkaline environments. This coordination
complex is really due to the hydroxyl amine. When other reducing agents are
used in the presence of ammonia in alkaline environments, then no similar
reaction product can be obtained.
EXPERIMENT 114
---------------
Aniline, combined with acidified dichromate gives intensely colored compounds.
EXPERIMENT 115
---------------
A large amount of sulphur can be added to bromine, before a solid remains in
the liquid bromine. The sulphur dissolves in the bromine very easily.
EXPERIMENT 116
---------------
A precipitate of nickel hydroxide is oxidized by persulfate to a black
compound (probably NiO2).
EXPERIMENT 117
---------------
Nickel (II) gives a black precipitate when treated with hydroxide and
persulfate at the same time. It is expected that this is an higher
oxide of nickel (NiO2).
EXPERIMENT 118
---------------
Hydrogen peroxide probably serves as a reductor for an higher oxide of
nickel.
EXPERIMENT 119
---------------
Permanganate is not capable of oxidizing nickel (II) in an acidic
environment. In an alkaline environment it appears to be possible to
oxidize nickel (II) with permanganate.
EXPERIMENT 120
---------------
Nickel does not appear to build coordination complexes with thiocyanate,
not even if acetone is added (in contrast to cobalt).
Ni(OH)2 is oxidized to a dark compound by persulfate, even in the presence
of a reducing agent like acetone.
EXPERIMENT 121
---------------
Nickel (II) does not form a coordination complex with ascorbic acid, not
in neutral or slightly acidic environments, nor in alkaline environments.
EXPERIMENT 122
---------------
Nickel (II) builds a stable complex with EDTA. Once this complex is formed,
it is not precipitated with NaOH and persulfate does not oxidize nickel (II).
EXPERIMENT 123
---------------
Nickel hydroxide can be oxidized by persulfate to a higher hydrous oxide
(nickel (III) and/or nickel (IV) oxide), but nickel carbonate is not
oxidized. The carbonate can be oxidized, however, when hydroxide is
added to the solution.
EXPERIMENT 124
---------------
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 125
---------------
Nickel forms colored coordination complexes with EDTA.
EXPERIMENT 126
---------------
Nickel (II) forms a complex with citrate. In a strongly alkaline environment
the nickel (II) does not precipitate. With just a small amount of ferric
ions present in the liquid, the complete liquid solidifies to a gelatin-
like constitution.
When the same experiment is done, without the nickel (II) present, no
solidification is observed.
EXPERIMENT 127
---------------
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 128
---------------
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 129
---------------
Antimony sesquioxide does not dissolve in a concentrated solution of NaOH
nor does it react with sulfide or one of the polysulfides in strongly
alkaline environments.
EXPERIMENT 130
---------------
Silver bromide is reduced by metol in alkaline medium.
EXPERIMENT 131
---------------
Diverse phenol-derivatives, can be oxidized easily by bromine, yielding
intensely colored oxidation products.
EXPERIMENT 132
---------------
Hydroquinone is a very strong reductor in alkaline environments. Oxygen
from the air is readily absorbed by an alkaline solution of hydroquinone.
Sulfite, however, makes an alkaline solution of hydroquinone much more
stable, because of formation of special hydroquinone/sulfite compounds.
EXPERIMENT 133
---------------
Hydroquinone is not oxidized to the dark brown product by hydrogen peroxide
as it is done by oxygen from the air in alkaline environments.
EXPERIMENT 134
---------------
Hydroquinone is readily oxidized by ferricyanide, even in the presence of
sulfite, when in alkaline environments.
EXPERIMENT 135
---------------
Metol is easily oxidized by oxygen from the air, when dissolved in alkaline
media. When sulfite is present, however, oxidation does only occur at a
low rate.
EXPERIMENT 136
---------------
Silver (I) is reduced to metallic silver by metol. This metallic silver
is easily oxidized by peroxosulfate.
Insoluble silver (I) compounds dissolve in thiosulfate solutions (principle
of photography fixer) while metallic silver is not affected.
When a mild oxidizer is added, the metallic silver also dissolves (principle
of photography reducer, Farmer's reducer).
EXPERIMENT 137
---------------
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 138
---------------
Pyrogallol does not dissolve in trichloroethene very well, but some of it
does dissolve.
EXPERIMENT 139
---------------
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 140
---------------
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 141
---------------
Phenidone is oxidized by air, but is much less susceptible to oxidation
than developers, such as hydroquinone, pyrogallol.
EXPERIMENT 142
---------------
Benzotriazole is not oxidized by air. Apparently it forms a coordination
complex with chromium (III).
EXPERIMENT 143
---------------
It appears that copper (II) ions catalyse the oxidation of pyrogallol by
hydrogen peroxide.
EXPERIMENT 144
---------------
Copper (II) apparently catalyses the oxidation of pyrogallol by oxygen from
the air.
EXPERIMENT 145
---------------
Pyrogallol gives rise to many colored products on oxidation and coordination.
More investigation is needed in order to get more insight in all these
colors and the conditions under which they are formed.
EXPERIMENT 146
---------------
Nitrite reacts with p-aminophenol violently in alkaline environments.
EXPERIMENT 147
---------------
Catechol, resorcinol and hydroquinone all are dihydroxy benzenes. When an
ortho-pair (1,2-pair) or a para-pair (1,4-pair) is present, then the compound
is easily oxidized by air in alkaline environment. When a meta-pair (1,3-pair)
is present, such a reaction does not occur.
EXPERIMENT 148
---------------
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 149
---------------
Pyrogallol reacts with chlorine, forming an orange/red compound. When excess
chlorine is used, this compound is further oxidized to an almost colorless
compound.
EXPERIMENT 150
---------------
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 151
---------------
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 152
---------------
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 153
---------------
Hydroxyl amine reacts with acetone, releasing (some) heat. After this
reaction, the resulting compound is shown to still be a relatively strongly
reducing agent in alkaline solution.
EXPERIMENT 154
---------------
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 155
---------------
Nitromethane gives a dark red/brown liquid in combination with aqueous sodium
hydroxide. This most likely is a polymeric species.
EXPERIMENT 156
---------------
Lead(II) hydroxide is easily converted to lead(II) oxide by simple boiling. The
lead(II) oxide appears as nice glittering gold/yellow crystals.
EXPERIMENT 157
---------------
When a solution of copper sulfate is added to a solution of hydroxyl ammonium
chloride in dilute solution of NaOH, then a dirty green precipitate is formed.
At some places the precipitate becomes yellow. When the liquid is shaken, then
all of the precipitate dissolves and a colorless liquid is obtained. On
standing, a thin layer of solid material is formed on the surface of the
liquid. This layer has a dirty green color.
Hydroxyl amine reduces copper(II) at high pH and a colorless complex of
copper(I) is formed, which at really high pH becomes unstable with formation of
hydrous copper(I) oxide.
EXPERIMENT 158
---------------
Arsenate ion and arsenic acid cannot easily be reduced to the element.
Reduction to trivalent arsenic, however, can easily be accomplished with
iodide.
EXPERIMENT 159
---------------
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 160
---------------
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 161
---------------
Nickel(II) ion is reduced in slightly alkaline environment by borohydride ion,
but only with difficulty, when the mix is heated.
EXPERIMENT 162
---------------
Both oxone, active ion is HSO5(-), and peroxodisulfate, active ion is S2O8(2-),
produce a black precipitate when added to nickel(II) ions at high pH. Hydrogen
peroxide, on the other hand, only produces green nickel(II) hydroxide, and if
the black precipitate is present, it is destroyed by hydrogen peroxide, with
formation of oxygen and green nickel(II) hydroxide.
EXPERIMENT 163
---------------
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 164
---------------
Thiourea is oxidized in acidic solution to formamidine disulfide, which exists
in solution as an acid salt. When a strong base is added, then the free base is
formed, but this at once decomposes. One of the decomposition products is
sulphur.
When excess oxidizer is used and the pH is increased strongly, then the sulphur
dissolves, giving rise to formation of polysulfides.
EXPERIMENT 165
---------------
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.
End of results for 'sodium hydroxide'