Nickel double salts

Key takeaways

Nickel double salts belongs to chemistry; place it in that map before memorising details.
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Reproduce the core statement of Nickel double salts from memory before moving on to harder problems.

Reference excerpt

Nickel can form various double salts.

Tutton's salts Nickel is one of the metals that can form Tutton's salts. The singly charged ion can be any of the full range of potassium, rubidium, cesium, ammonium (NH4), or thallium.

Mineral forms As a mineral the ammonium nickel salt, (NH4)2Ni(SO4)2 · 6 H2O, can be called nickelboussingaultite. With sodium, the double sulfate is nickelblödite Na2Ni(SO4)2 · 4 H2O from the blödite family. Nickel can be substituted by other divalent metals of similar sized to make mixtures that crystallise in the same form.

Langbeinites

Anhydrous salts of the formula M2Ni2(SO4)3, which can be termed metal nickel trisulfates, belong to the family of langbeinites. The known salts include (NH4)2Ni2(SO4)3, K2Ni2(SO4)3 and Rb2Ni2(SO4)3, and those of Tl and Cs are predicted to exist.

Double halides

Fluorides Double fluorides include the fluoroanion salts, and those fluoronickelates such as NiF4 and NiF6:

KNiF3·H2O and NaNiF3·H2O – apple green coloured aluminium nickel pentafluoride (AlNiF5·7H2O) ceric nickelous decafluoride (Ce2NiF10·7H2O) niobium nickel fluoride (Ni3H4Nb2F20·19H2O) vanadium nickel pentafluoride (VNiF5·7H2O) vanadyl nickel tetrafluoride (VONiF4·7H2O) chromic nickelous pentafluoride (CrNiF5·7H2O) molybdenum nickel dioxytetrafluoride (NiMoO2F4·6H2O) tungsten nickel dioxytetrafluoride hexahydrate (NiWO2F4·6H2O) and decahydrate (NiWO2F4·10H2O) manganic nickel pentafluoride (MnNiF4·7H2O) nickelous ferric fluoride (FeNiF5·7H2O)

Chlorides

Trichlorides Nickel trichloride double salts exist which are polymers. Nickel is in octahedral coordination, with double halogen bridges. Examples of this include RbNiCl3, pinkish tan coloured H2NN(CH3)3NiCl3. Other double trichlorides include:

potassium nickel trichloride (KNiCl3·5H2O) yellow cesium nickel trichloride (CsNiCl3) lithium nickel trichloride (LiNiCl3·3H2O) nickel ammonium chloride hexahydrate (NH4NiCl3·6H2O)

Tetrachlorides

The tetrachloronickelates contain a tetrahedral NiCl42− and are dark blue. Some salts of organic bases are ionic liquids at standard conditions. Tetramethylammonium nickel trichloride is pink and very insoluble. Other tetrachlorides include:

hyrdrazinium nickel tetrachloride lithium nickel tetrachloride (Li2NiCl4·4H2O) – stable from 23 to 60° rubidium nickel tetrachloride stannous nickel tetrachloride (SnCl2·NiCl2·6H2O)

Hexachlorides Double hexachlorides include:

cadmium dinickel hexachloride (CdCl2•2NiCl2•12H2O) – crystallises in hexagonal system dicadmium dinickel hexachloride (2CdCl2•NiCl2•12H2O) – rhombic crystals, pleochroic varying from light to dark green. lithium nickel hexachloride Li4NiCl6·10H2O – stable from 0 to 23° stannic nickel hexachloride (SnCl4·NiCl2·6H2O) – tetragonal

Octochlorides Thallic nickel octochloride 2TlCl3·NiCl2·8H2O is bright green.

Oxychlorides Copper nickel dioxychloride 2CuO·NiCl2·6H2O and copper nickel trioxychloride 3CuO·NiCl2·4H2O exist.

Bromides

Double bromides include the tetrabromonickelates. Other salts include:

caesium nickel tribromide (CsNiBr3) copper nickel trioxybromide (3CuO·NiBr2·4H2O) didymium nickel bromide (2(Pr,Nd)Br3·3NiBr2·18H2O) – reddish brown, mixture of praseodymium and neodymium lanthanum nickel bromide (2LaBr3·3NiBr2·18H2O) mercuric nickel bromides (Hg2NiBr6) and (HgNiBr4) mercuric nickel oxybromide (6NiO·NiBr2•HgBr2•20H2O) – prepared by reacting nickel bromide with mercuric oxide nickel stannic bromide or nickel bromostannate (NiSnBr6·8H2O) – apple green

Iodides

The tetraiodonickelates are blood-red coloured salts of the NiI4 ion with large cations. The diperiodatonickelates of nickel(IV) are strong oxidisers, and akali monoperiodatonickelates also are known. Double iodides include:

mercuric nickel hexaiodide (2HgI2·NiI2 · 6 H2O) mercuric nickel tetraiodide (HgI2·NiI2 · 6 H2O) lead nickel hexaiodide (I2·2NiI2 · 3 H2O)

Double nitrates

Lanthanides Nickel forms double nitrates with the lighter rare-earth elements. The solid crystals have the formula Ni3Me2(NO3)12•24H2O. The metals include La, Ce, Pr, Nd, Sm, Gd and the non rare earth Bi. Nickel can also be replaced by similar divalent ions Mg, Mn, Co, and Zn. For the nickel salts melting temperatures range from 110.5° for La, 108.5° for Ce, 108° for Pr, 105.6° for Nd, 92.2° for Sm and down to 72.5° for Gd, the Bi salt melting at 69°. Crystal structure is hexagonal with Z=3. Ni3La2(NO3)12•24H2O becomes ferromagnetic below 0.393 K. These double nickel nitrates have been used to separate the rare earth elements by fractional crystallization.

Actinides Nickel thorium nitrate has formula NiTh(NO3)6 · 8 H2O. Nickel atoms can be substituted by other ions with radius 0.69 to 0.83 Å. The nitrates are coordinated on the thorium atom and the water to the nickel. Enthalpy of solution of the octahydrate is 7 kJ/mol. Enthalpy of formation is -4360 kJ/mol. At 109° the octahydrate becomes NiTh(NO3)6•6H2O, and at 190° NiTh(NO3)6•3H2O and anhydrous at 215°. The hexahydrate has Pa3 cubic structure.

Double nitrites

Double amides Various double amides containing nickel clusters have been made using liquid ammonia as a solvent. These are called amidonickel compounds. These include:

Li3Ni4(NH2)11·NH3 (Pna21; Z = 4; a = 16.344(3) Å; b = 12.310(2) Å; c = 8.113(2) Å v=1631 D=1.942) – red Li4Ni4(NH2)12·NH3, Na2Ni(NH2)4 Na2Ni(NH2)4•NH3 Na2Ni(NH2)4•2NH3 – orange red K2Ni(NH2)4•0.23KNH2 Rb2Ni(NH2)4•0.23RbNH2 Cs2Ni(NH2)4•NH3 (P21/c; Z = 4; a =9.553(3) Å; b = 8.734(3) Å; c = 14.243(3) Å; β = 129.96(3)° V=910 D=2.960)

Double hydrides Double hydrides of nickel exist, such as Mg2NiH4.

Double dihydrogen phosphides Nickel dihydrogen phosphide (Ni(PH2)2) can form orange, green or black double salts KNi(PH2)3) that crystallise from liquid ammonia. They are unstable above -78 °C, giving off ammonia, phosphine and hydrogen.

Double tetrafluoroberyllates

Nickel forms double salts with Tutton's salt structure with tetrafluoroberyllate and a range of cations including ammonia, potassium, rubidium, cesium, and thallium.

Other minerals Some minerals are double salts, for example nickelzippeite Ni2(UO2)6(SO4)3(OH)10 · 16H2O which is isomorphic to cobaltzippeite, magnesiozippeite and zinczippeite, part of the zippeite group.

Table of nickel double salts

References

Worked examples

Example 1 — a first encounter with Nickel double salts

Start with the simplest possible case. Write down what Nickel double salts claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Nickel double salts before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Nickel double salts ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Nickel double salts

In research: Nickel double salts appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Nickel double salts in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Nickel double salts is common in secondary-school and first-year university syllabi. It links to neighbouring topics Double salts, Incomplete science lists, Nickel compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Nickel double salts outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Nickel double salts in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Nickel double salts means in your own words.
Compare your version with the excerpt and mark what you missed.
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Frequently asked questions

What is Nickel double salts in simple terms?

Nickel can form various double salts. Tutton's salts Nickel is one of the metals that can form Tutton's salts.

Why does Nickel double salts matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Nickel double salts?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Nickel double salts.