Science made alive: Chemistry/Experiments

Experiments with first row transition metals and their compounds

	element	required compound	link to experiment
	Co	CoCl₂·6H₂O	Preparation of anhydrous cobalt(II) chloride. Careful heating of hydrated cobalt chloride produces the anhydrous compound.
*	Co, Hg	HCl (30%) HgCl₂ NH₄SCN any water soluble cobalt(II) salt	Colorful and really remarkable chemistry. In this experiment some amazing color changes can be observed. A beautiful bright red solution is prepared from which slowly very bright blue crystals are precipitated. Beautiful contrasts are produced in this experiment.
*	Cr	Cr (pure metal) HCl (30%)	Divalent chromium, extreme sensitivity to aerial oxidation. Chromium metal is dissolves in conc. hydrochloric acid with exclusion of air, and then it is shown how easily the resulting chromium(II) species are oxidized.
*	Cr	K₂Cr₂O₇ (NH₄)₂Cr₂O₇ HNO₃ (concentrated) P (red) Na₂SO₃	Synthesis and properties of polychromates. Trichromates are produced by recrystallization from conc. nitric acid. Some properties, including a spectacular decomposition reaction, are shown.
	Cr	K₂Cr₂O₇ Cr₂(SO₄)₃·12H₂O	Anhydrous chromium(III) sulfate from concentrated sulphuric acid? Concentrated sulphuric acid, with dissolved chromium compounds, is heated and a precipitate is formed.
*	Cr	K₂Cr₂O₇ H₂SO₄ (dilute) HCl (dilute) HNO₃ (dilute) CH₃CH₂OH K₂S₂O₅ (or subst.)	Reduction of dichromate - different colors of reaction product due to complex formation. Dichromate is reduced. The color of the resulting chromium(III) depends on the reductor used, and the anions, present in that solution.
*	Cr	(NH₄)₂CrO₄	Nice dendritic crystal structures. Ammonium chromate is dissolved and the solution is allowed to evaporate to dryness.
	Cr	K₃CrO₈	Explosive properties of peroxo chromates. A synthesis method for this chemical is given, and its explosive properties are shown.
	Cr	K₂Cr₂O₇ H₂O₂ any mineral acid	Beautiful effects with potassium dichromate and hydrogen peroxide. Potassium dichromate crystals are sprinkled on a highly diluted acidic hydrogen peroxide solution. The effect is stunning.
*	Cr	K₂Cr₂O₇ NaF NaCl H₂SO₄ (concentrated) H₂O₂	Fun with volatile chromium - chromyl chloride . A really beautiful experiment with chromyl chloride vapor, which is poured on a very dilute acidic hydrogen peroxide solution.
*	Cr	K₂Cr₂O₇ NaF NaCl H₂SO₄ (concentrated) Na₂SO₃	Volatile compounds of chromium - another colored gas . Preparation of chromyl fluoride and chromyl chloride.
*	Cr	H₂O₂ K₂Cr₂O₇ KOH	Synthesis of potassium tetraperoxo chromate(V) . A detailed description (recipe) for making the energetic compound K₃CrO₈.
*	Cr	H₂O₂ (NH₄)₂CrO₄ NH₃ (25%)	Synthesis of triammine diperoxo chromium(IV). This is a description of how to make another very energetic chromium peroxo compound. Also some properties of the prepared compound are shown.
*	Cr	K₂Cr₂O₇ HCl (≥ 25%, high purity reagent) Na₂SO₃ HCl (dilute, hardware store)	Synthesis of potassium chlorochromate(VI). The compound potassium chlorochromate(VI) can easily be prepared. In this webpage it is demonstrated how this can be done with acceptable yield. The resulting chemical compound can be kept indefinitely and may be interesting for further experiments.
*	Cr	H₂O₂ Na₂Cr₂O₇·2H₂O C₅H₅N (pyridine) Na₂SO₃ H₂SO₄	Chromium peroxo pyridine complex and its properties. A dark blue insoluble peroxo complex of chromium is made, and some further experiments are performed with this compound. This experiments shows some remarkable color combinations and the peroxo complex is remarkably stable under reducing conditions.
*	Cr	K₃CrO₈ P (red) Al (powder)	Explosive mix with red phosphorus and a peroxo chromate . A remarkably powerful and sensitive explosive mix is obtained by mixing potassium tetraperoxochromate(V) and red P.
*	Cr	KCr(SO)₄·12H₂O NH₃ (5% and 12%) HCl (10%) NaOH	Chromium(III) coordination chemistry. This is a simple experiment which shows that by simple boiling an aqueous solution of chromium(III) ions forms a complex with anions present in solution by means of ligand exchange. The experiment demonstrates this effect with sulfate anions, but the effect also exists for many other anions. The ligand exchange is accompanied with a strong change of color.
*	Cr	Na₂CrO₄ or K₂CrO₄ NH₄NO₃ or (NH₄)₂SO₄ NH₃ (dilute)	Temperature-dependence of chromate/dichromate equilibrium. In this experiment it is shown that the well-known change of color from orange dichromate to yellow chromate or v.v. has a strong dependence on temperature. The color change also can be effected by heating and cooling down.
*	Cu	CuSO₄·5H₂O NH₃ (5%) NaOH Na₂SO₃ C₆H₈O₅Na (sodium L-ascorbate) Na₂S₂O₄·2H₂O	Copper redox and coordination chemistry. A series of experiments in which redox and coordination properties of copper are shown. Copper has a very rich aqueous chemistry and this set of experiments shows some of this rich chemistry.
*	Cu	Al (foil) NaCl CuSO₄·5H₂O HCl (10%)	Influence of combination of copper ions and chloride ions on reactivity of aluminium. A violent reaction only occurs, when both type of ions are present.
	Cu	CuCl₂ (or its hydrate)	Colored flames with metal salts. Metals salts are mixed/dissolved in ethanol, soaked in paper and ignited. One of the salts is copper(II) chloride.
*	Cu	CuSO₄·5H₂O KSCN Na₂SO₃ HNO₃	Complex chemistry of copper in combination with thiocyanate. Copper exhibits an interesting chemistry when it is combined with thiocyanate ion. An intricate interplay of coordination chemistry and redox chemistry leads to many surprising compounds with nice colors.
*	Cu	CuSO₄·5H₂O KIO₄ KOH Na₂S₂O₈	Formation of a complex of copper in oxidation state +3. Copper can be oxidized to the +3 oxidation state if it is coordinated to orthoperiodate ions. This complex is stable in aqueous solution, and it has a deep red color, which is very special for copper compounds.
*	Cu, S	CuSO₄·5H₂O 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.
*	Cu	CuSO₄·5H₂O HBr (48%) HCl (30%) KBr	Unexpected colors with copper(II) ions in the presence of halogenide at high concentration. Copper(II) ions form intensely colored red/purple complex ions with bromide at low pH and high concentration.
*	Cu organic	CuI KI C₅H₅N CH₃COCH₃	A fluorescent compound of copper. This is an experiment, which is not well known. The effect demonstrated in this experiment, however, is striking and it is a shame that so few people know it. A white compound is prepared which exhibits beautiful bright yellow fluorescence under black-light.
*	Cu organic	CuCO₃·Cu(OH)₂ CH₃COOH CH₂ClCOOH CCl₃COOH HCOOH CH₃CH₂COOH CH₃C(OH)HCOOH	Inductive effect demonstrated by properties of copper acetate and related complexes. In this experiment, copper acetate, but also several substituted and related compounds are prepared. Their properties are compared and a good explanation can be given by the inductive effect.
*	Cu, Cs	CuCl₂·2H₂O CsCl HCl (30%) CoCl₂·6H₂O (optional) FeCl₃·6H₂O (optional)	Red complex of copper and chloride. A really beautiful and remarkable solid chloro complex of copper is produced. The complex has copper in oxidation state +2 and has a bright red color, which is very special for copper in oxidation state +2. A few other similar complexes of other metals are described as well through this webpage.
*	Fe	FeCl₃·6H₂O FeSO₄·7H₂O NH₃ HCl	Preparation of a compound with magnetic properties. Only very mundane chemicals and equipment are needed in this simple, but funny experiment. A precipitate of magnetite is prepared and the precipitate is drawn through a test tube by moving a strong magnet around the test tube.
*	Fe	K₃Fe(CN)₆ CH₃COOH (white vinegar) (NH₄)₃[Fe(C₂O₄)₃] instead of "ferric ammonium oxalate", "ferric ammonium citrate" can be used as well	Cyanotype, the dawn of photography. One of the oldest processes for making permanent images is demonstrated in this experiment. Using simple chemicals and tools an image (a blue print) is made from flat objects like leaves. The word 'blue print' originally stems from this process.
*	Fe, Mn	any soluble Mn salt any soluble Fe salt bleach	Oxidizing power of bleach, bringing iron and manganese to highest oxidation state. Simple household bleach is capable of oxidizing iron to its +6 oxidation state and manganese to its +7 oxidation state.
*	Mn	KMnO₄ C₁₂H₂₂O₁₁ (sugar) NaOH	Chemical chameleon with permanganate. A dilute solution of potassium permanganate is reduced with an alkaline sugar solution. The solution slowly goes through many colors.
*	Mn	KBrO₃ CH₂(COOH)₂ MnSO₄·xH₂O H₂SO₄ (dilute)	Oscillating reaction. The classical Bhelousov-Zhabotinsky reaction. A well-known classical, but very beautiful, experiment.
*	Mn	KMnO₄ H₂SO₄(concentrated) CH₃COCH₃	High speed image capturing of explosions . A drop of acetone is dripped on a mix of concentrated sulphuric acid and potassium permanganate. The resulting explosion is filmed at 60 frames per second.
*	Mn	KMnO₄ H₂SO₄(concentrated) CH₃COCH₃	Liquid from hell -- fire on first contact . This is a spectacular demonstration, very similar to the one above. Acetone, sticking to a glass rod, is put in a mix of conc. sulphuric acid and potassium permanganate.
*	Mn	KMnO₄ H₂SO₄(concentrated) CH₃CH₂OH	Miniature explosions in a test tube . Potassium permanganate is put in a test tube, containing sulphuric acid, with a layer of ethanol floating on top of the acid. This results in little flashes and crackling noise, after an induction period of a few minutes.
*	Mn	KMnO₄ NaF H₂SO₄ (concentrated) Na₂S₂O₅ (or Na₂SO₃)	A volatile compound of manganese and corrosion of glass . A volatile green compound of manganese(VII) is produced from potassium permanganate, sodium fluoride and conc. sulphuric acid.
*	Mn	Mn (very pure 99.99%) MnCl₂ (hydrated is OK) HCl (37%, reagent grade) KMnO₄ (reagent grade) H₂O₂ (10% by weight) Na₂SO₃	Properties of manganese(II) ion at very high concentration. In this experiment it is shown that manganese(II) ions in aqueous solution are pale pink, also at very high concentration and in the presence of concentrated hydrochloric acid. This is different from what some textbooks claim, which mention the existence of green complexes.
	Mn	MnO₂ Al (powder) P (red)	Flash powder with manganese dioxide. Manganese dioxide and fine aluminium powder make a powerful flash powder. With red P it can be ignited more easily.
*	Ni	NiSO₄·xH₂O NaOH KCN H₂SO₄ (dilute) H₂O₂ ligroin (boiling 40...60 °C) bleach	Nickel in oxidation state +1. In this experiment, nickel is brought to the remarkable oxidation state +1, which is very special for this metal, which usually is in oxidation state +2 in aqueous solutions.
*	Ni	Na₂S₂O₈ HNO₃ (dilute) NiSO₄·xH₂O NaOH	Very high oxidation state of nickel with persulfate. Nickel is brought to +3 or even +4 oxidation state by persulfate ion under alkaline conditions.
*	Ni, Cu	NiSO₄·xH₂O NH₂CH₂CH₂NH₂ NiNO₃.6H₂O NH₄ClO₄ H₂O₂ NiCO₃ HClO₄ (aqueous) CuO	Nickel - ethylenediamine complexes. Nickel forms differently colored complexes with ethylenediamine. These complexes have strong bright colors. The tris-complex also can be crystallized easily with different cations, most notably the perchlorate ion. The solid perchlorate is an energetic and beautifully looking compound. This webpage also contains a link to an experiment, in which the copper complex is made as perchlorate salt. This also is easily crystallized and has equally energetic properties as the nickel complex.
*	Ti	Ti (powder, granules) HCl (30%) H₂O₂ (3%) Na₂SO₃ Na₂S₂O₈	Aqueous chemistry of titanium. Titanium is dissolved in hydrochloric acid. The resulting purple solution is used as a starting point for exploring the metal's aqueous chemistry.
*	V	V₂O₅ Zn (filings, granules) NaOH HCl (dilute) Na₂SO₃	Colorful oxidation states of vanadium. Vanadium pentoxide is dissolved in a solution of sodium hydroxide. This solution is acidified and then the vanadium in its +5 oxidation state is reduced, all the way down to +2 oxidation state.
*	V	V₂O₅ KOH H₂O₂ (15%) H₂SO₄ (dilute) CH₃CH₂OH (96%) P (red)	Isolation of peroxo complex of vanadium. In this experiment a peroxo complex of vanadium is made and this complex is isolated as a dry powdered solid. The isolated compound is stable on storage and has energetic properties. A mix with red phosphorus deflagrates on ignition.
*	V	V₂O₅ PCl₅	Volatile vanadium compound, leading to green gas and red smoke. Phosphorus pentachloride is capable of chlorinating vanadium pentoxide and the resulting compound is volatile and gives rise to formation of interesting green vapor and red smoke when it is heated.
	V	V₂O₅ H₂SO₄ Na₂SO₃ NaOH (NH₃OH)₂SO₄	Same compound, useful as oxidizer and as reductor. Vanadium can be oxidized by hydroxylamine from its +4 oxidation state to +5 oxidation state, but it can also be reduced from its +5 oxidation state to the +4 oxidation state. This depends on pH.
*	Zn, Cu	Zn (granules or sheet) ZnO NaOH Cu (coin) dilute HNO₃ / vinegar	Zinc plating of copper coin. A copper coin is zinc plated by putting it in an alkaline solution, containing zincate ions, while at the same time the coin touches a piece of metallic zinc.

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