Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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sulphur : S8
ligroin : C7H16
nitric acid : HNO3
acetone : CH3 CO CH3
sulphuric acid : H2SO4
potassium permanganate : KMnO4
Class:
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elem=Mn
redox
Summary:
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Permanganate is a strong (and dangerous) oxidizer, when combined with
concentrated sulphuric acid. It is capable of lighting paper and acetone,
without the use of matches.
Permanganate, mixed with a mixture of nitric acid and sulphuric acid is
a strong oxidizer as well, but not as powerful as when mixed with
sulphuric acid only.
Description:
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Experiment 1:
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Put a little amount of KMnO4 on a piece of paper (just a few cubic millimeters
of solid are placed on the paper in the form of little crystals) and put one
drop of concentrated H2SO4 (96 - 98 %) on the solid KMnO4: The crystals
dissolve in the acid. A few seconds later the liquid starts foaming. A few
seconds after the initial foaming it suddenly becomes more violent. A vapor
with a purple/brown color escapes from the liquid and an orange light is
emitted from the reaction mixture (it becomes very hot). After the reaction
a little hole is burned in the piece of paper and around the reaction mixture
brown soot-like flakes can be found at distances of up to a few tens of cm
from the reaction mixture. These flakes can easily be blown away.
Experiment 2:
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Put a few cubic millimeters of KMnO4 on a piece of glas and put one drop of
concentrated H2SO4 (96 - 98 %) on the solid: The solid dissolves and the drop
of concentrated acid becomes dark brown/green.
Put a little piece of paper on the dark drop of acid: After appr. 2 seconds
a sudden violent reaction occurs with appearance of fire (orange/violet
light is emitted).
Experiment 3:
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Put a few cubic millimeters of KMnO4 on a piece of glas and put one drop of
concentrated H2SO4 (96 - 98 %) on the solid: The solid dissolves and the drop
of concentrated acid becomes dark brown/green.
Put a drop of acetone on the dark brown/green drop: As soon as the drop of
acetone touches the dark drop of acid, it starts burning. The heat of reaction
is sufficient to light the flammable liquid.
Experiment 4:
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Put a few cubic millimeters of KMnO4 on a piece of glas and put one drop of
a mixture of concentrated H2SO4 (96 - 98 %) and concentrated HNO3 (appr. 65%
by weight), each acid appr. 50 % by volume: The solid KMnO4 dissolves, the
liquid becomes almost black. The drop fumes (just as the mixture of the
acids does).
Put a piece of paper (appr. 1 square cm) on the dark drop: After a few seconds
the fuming becomes a little stronger. A soft hizzing noise of foaming can be
heard (not seen, due to the little piece of paper). No signs of fire can be
observed, the paper does not burn.
Experiment 5:
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Put a few cubic millimeters of KMnO4 on a piece of glas and put one drop of
a mixture of concentrated H2SO4 (96 - 98 %) and concentrated HNO3 (appr. 65%
by weight), each acid appr. 50 % by volume: The solid KMnO4 dissolves, the
liquid becomes almost black. The drop fumes (just as the mixture of the
acids does).
Put a few drops of acetone on the dark drop of acid mixture: The liquid starts
foaming vigorously and white fumes are evolved. The acetone is not lit.
Experiment 6:
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Put a drop of sulphuric acid to the same volume of solid KMnO4: The drop of
acid becomes brown/black (THIS IS AN EXTREMELY DANGEROUS MIXTURE).
Keep a drop of ligroin close to the acidic drop, but do not let the drop of
ligroin touch the drop of sulphuric acid with KMnO4: Little sparks of light
are observed at the surface of the dark drop. The ligroin does not catch fire.
Put a little piece of paper (appr. 2 cm x 2 cm) on top of the dark drop: A
very vigorous reaction occurs, the orange light of the fire-like reaction can
be observed through the paper, while the top side of the paper is not affected.
Press the paper into the drop with a little glas rod: The reaction mixture
under the piece of paper explodes. The piece of paper is torn apart in two
pieces and a spray of minute dark droplets is created. Little black droplets
fall down, causing chemical burns in the table and the paper on the walls.
These black droplets reach a distance of almost 1 meter from the reaction
mixture.
Experiment 7:
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Make a mix of KMnO4 and sulphur. Take a few cubic millimeters of this
mixture and add a drop of sulphuric acid to the mixture: The drop becomes
brown/black. There is no visible reaction. The sulphur does not cause a
violent redox reaction.
Add a little piece of paper: As soon as the paper comes in contact with the
acid/KMnO4/S mixture, then the mixture reacts violently with signs of fire.
Part of the piece of paper burns.