Experiments, lexicographically ordered

 

  element required compound link to experiment
 

S

KIO4

S

Pyrotechnic mix with purple gaseous combustion product. Potassium periodate, mixed with sulphur gives a mix, which burns without smoke, but produces a nice purple gas mix of iodine and sulphur dioxide.

*

S

KIO4

NH4SCN

Colored smoke -- purple and yellow. A mix of potassium periodate and ammonium thiocyanate is ignited. This gives purple smoke, which quickly turns yellow. Quite a remarkable experiment.

*

S

S8

C6H5CH3

Recrystallization and/or refining of sulphur. Sulphur is dissolved in hot toluene and when this solution cools down, nice crystals of sulphur are formed.

*

S, C, N

N2O

CS2

Barking dog reaction . Nitrous oxide is mixed with carbon disulfide vapor and this mix is ignited. This results in a very spectacular reaction with bright light and an impressive barking noise in which yellow elemental sulphur is deposited.

 

S

SOCl2

H2SO4 (concentrated)

K2Cr2O7

Thionyl chloride and potassium dichromate, no reduction of dichromate without water. Potassium dichromate is dissolved in thionyl chloride. It is not reduced to chromium(III). With concentrated sulphuric acid and water, chromyl chloride and HCl are formed.

* S, Cu

CuSO45H2O

Na2SO3

Na2S2O5

H2SO3

NaOH

Redox chemistry and coordination chemistry of copper(II) and sulfite at different pH. Sulfite ion and copper(II) ion can react in different ways. Coordination complexes can be formed, but they also can interact in a redox reaction. Quite remarkable compounds can be formed in these reactions. The pH of the solutions has great influence on the actual reactions occurring.
* Se

Se

Na2S.xH2O

H2SO4 (dilute)

NaOH

Na2S2O8

Na2SeO3

SeO2

HBr (40%, 48%)

Na2SO3

Less common aspects of selenium chemistry . The element selenium has some interesting properties in combination with sulfide and bromide. It can form strongly colored species, which are stable in aqueous solution and can be studied without the need of exotic solvents.
*

Se

Se

HNO3 (≥ 50 %)

Zn

Na2SO3 (or Na2S2O5)

Allotropes of selenium. Gray selenium is dissolved in conc. nitric acid, giving selenous acid in solution. This solution in turn is reduced to selenium. The selenium now precipitates as the red allotrope.

*

Te, Se, S

Te

Se

S

NaH2PO2H2O

Na2SxH2O

K2Cr2O7

H2SO4 (concentrated)

H2O2 (3%)

P4O10 (optional)

SO3 (20% oleum)

Poly cation species of tellurium and selenium, no similar reaction with sulphur under the same conditions. Tellurium and selenium are dissolved in hot concentrated sulphuric acid. The solutions contain remarkable cationic species with peculiar structure.

Sulphur does not show such a reaction in sulphuric acid, but it does react with oleum.

*

Te

Cl, Br, I

TeO2

Na2TeO3

HCl (30% by weight)

HBr (40% by weight)

H2SO4 (dilute)

KI

Na2SO3

Colorful properties of halogen complexes of tellurium in oxidation state +4. At very low pH, tellurium in oxidation state +4 forms remarkable compounds with the halide ions. The heavier the halogen, the more stable the complex and the more intense the color. All of these complexes, however, are very prone to hydrolysis in aqueous solution.

 

 

   

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