Experiments for 'potassium dichromate'
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 'potassium dichromate':
EXPERIMENT 1
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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 2
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Potassium dichromate is sparingly soluble in thionyl chloride, giving an
intensely colored red/orange/brown solution, which on addition to water
at once becomes green with a blue hue.
Potassium chromate does not dissolve in thionyl chloride. The solid changes
color from yellow to yellow/orange, and the solution becomes slightly colored,
but this faint reaction may be due to minor impurities in the potassium
chromate or thionyl chloride. If any potassium chromate dissolves, then it
is a very small amount.
EXPERIMENT 3
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Thionyl chloride is not soluble in concentrated sulphuric acid, or only
sparingly soluble.
The mix of thionyl chloride and sulphuric acid is capable of forming chromyl
chloride from potassium dichromate.
EXPERIMENT 4
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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 5
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Potassium dichromate reacts with formic acid, producing a gas (CO2) and
itself being reduced to trivalent chrome.
EXPERIMENT 6
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Acrylic acid fairly easily is oxidized in dilute aqueous solution, while propanoic acid is not.
The double bond between two C-atoms makes the molecule more reactive.
EXPERIMENT 7
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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 8
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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 9
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Chromium (III) has many different colors, depending on coordinated ligands.
EXPERIMENT 10
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Chromium (III) has many different colors, depending on coordinated ligands.
EXPERIMENT 11
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Chromium (III) can have many different colors, depending on how it is
created and with which it coordinates.
EXPERIMENT 12
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The color of chromium (III) depends on how it is part of coordination
complexes.
EXPERIMENT 13
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Potassium dichromate dissolves very well in hot water. In the cold nice
crystals separate out of the solution.
EXPERIMENT 14
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Silver (I) gives a bordeaux-red precipitate with dichromate, which
slightly dissolves in water.
EXPERIMENT 15
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Basic chromium (VI), chromate, is not capable of oxidizing ascorbate. On
acidification, immediate oxidation occurs and a coordination complex is
formed.
EXPERIMENT 16
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When chromium (III) is created by reduction from dichromate with acidified
sulfite, then a green ion is formed. When acidified sulfite is added to
violet chromium (III), then the ions remain violet.
Apparently the way of creating chromium (III) determines its color (and
hence to what it is coordinated).
EXPERIMENT 17
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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 18
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Chromate is reduced by dithionite in strongly alkaline solution, but this
reaction proceeds slowly.
EXPERIMENT 19
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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 20
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Hexavalent chrome forms a stable volatile compound, when mixed with chloride
in strongly dehydrating conditions. The compound formed is called chromyl
chloride and its constitution is CrO2Cl2.
EXPERIMENT 21
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From ice cold strongly alkaline solutions of potassium chromate, one can
create peroxochromate by adding hydrogen peroxide carefully.
EXPERIMENT 22
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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 23
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Chromium (III) builds a coordination complex with nitrite of a fairly
intense purple color.
EXPERIMENT 24
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Chromium (III) builds a purple complex with EDTA, both when it is created
from dichromate and when it already exists and is brought in contact with
EDTA. When the pH is too low (or is this due to formation of a complex with
sulfate?), the formation of the complex does not occur.
EXPERIMENT 25
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When dichromate is brought in contact with peroxide, then after an initial
transient, a green variation of chromium (III) is produced. This compound,
however, slowly changes to a bluish/violet compound.
EXPERIMENT 26
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When dichromate is reduced with metabisulfite in acidic environment, then
a chromium (III) compound is formed, which does not easily crystallize
from the liquid as chrome alum. The chromium (III) compound is green,
instead of violet.
EXPERIMENT 27
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When dichromate is reduced by means of adding hydrogen peroxide, then after
the initial transient a green compound is formed, even when the acid in
which the dichromate is dissolved is nitric acid (nitrate is supposed to
not form a coordination complex with chromium (III)). Is this green compound
a coordination complex with nitrate? or with hydrogen peroxide?
This coordination complex can easily be destroyed by heating.
EXPERIMENT 28
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Dichromates are not capable of oxidizing nitrite in neutral environments.
When some acid is added, then the oxidation proceeds, but a fairly low
pH is needed for a fast and complete reaction.
EXPERIMENT 29
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Dichromate is not capable of oxidizing formiate in reasonable time.
EXPERIMENT 30
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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 31
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Chromium (III) builds a nice brightly colored green complex with phosphates.
This compound has no bluish hue, like sulfate gives with chromium (III).
Chloride also builds a complex. Formation of these complexes is not on
simple addition of a chromium (III) salt to the corresponding anions.
Heating is required.
EXPERIMENT 32
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Dichromate can be reduced by hydrochloric acid with some difficulty.
EXPERIMENT 33
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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 34
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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 35
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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 36
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When dichromate is added to sulfide, then a transient highly coloured
compound is formed, immediately followed by reduction to green chromium (III)
in alkaline environment.
EXPERIMENT 37
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Potassium dichromate dissolves in methanol, albeit not as well as in water.
Potassium chromate hardly dissolves in methanol. When ammonium thiocyanate
is added, then the liquid becomes deep yellow. Is this due to chromate, or
is this some reaction product from the thiocyanate?
EXPERIMENT 38
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Aniline, combined with acidified dichromate gives intensely colored compounds.
EXPERIMENT 39
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Aniline gives colored compounds with chromium. The colors are remarkably
intense.
EXPERIMENT 40
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Antimony (III) is oxidized by dichromate in acidic environments.
EXPERIMENT 41
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Phenidone can be oxidized by potassium dichromate and the oxidation
product appears to be a solid, dark brown compound, which does not
dissolve in water.
EXPERIMENT 42
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Benztriazole cannot be oxidized by acidified dichromate. Metol is
quickly oxidized.
EXPERIMENT 43
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When p-aminophenol is oxidized in an acidic environment, then a compound
is formed, with a deep indigo/purple color.
EXPERIMENT 44
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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 45
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Dichromate is quickly reduced by tin (II) ions.
Hydrogen peroxide does not show a visible reaction with tin (II) ions.
EXPERIMENT 46
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Dichromate/chromic acid is reduced by malic acid and in this reaction an
intensely colored purple complex of chromium(III) is formed. If the reaction is
performed in the presence of an excess amount of strong non-coordinating acid,
then the reaction proceeds faster, and also a purple complex is formed, but the
color is much less intense.
Without the extra acid, there really is a new complex with chromium(III). This
complex reacts with ammonia, giving a nice green solution.
EXPERIMENT 47
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Hexavalent chromium oxidizes ascorbic acid. This reaction is fast and even
proceeds without adding additional acid. The acidity of the ascorbic acid
suffices to make the reaction proceed quickly.
The resulting chromium(III) forms an intensely colored dull-green complex
(green/grey, almost black at moderate concentration).
EXPERIMENT 48
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Hexavalent chromium is reduced to trivalent chromium by hypophosphite, but
there is no further reduction to chromium(II).
EXPERIMENT 49
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Sodium dichromate anhydrous dissolves in methanol quite well, but does not
react with it. When a little concentrated sulphuric acid is added, then
suddenly a very violent reaction occurs.
With potassium dichromate, this violent reaction does not occur. The latter is
nearly insoluble in methanol and hence it hardly can react with it.
EXPERIMENT 50
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Thallium(I) chromate and thallium(I) dichromate both are insoluble (or at most
marginally soluble) in water. Thallium(I) is not a sufficiently strong reductor
to get the hexavalent chromium reduced.
EXPERIMENT 51
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Chlorosulfonic acid is an extremely reactive compound. It reacts violently with
many salts of oxoacids.
EXPERIMENT 52
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Dichromate and chromate both quickly are oxidized by pure formic acid,
resulting in a fairly violent and exothermic reaction, in which a dark
purple/blue/grey compound is formed.
End of results for 'potassium dichromate'