science

Tutton's salt

Tutton's salt is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Tutton's salt rather than just read about it. In short: Tutton's salts are a family of salts with the formula M2M'(SO4)2(H2O)6 (sulfates) or M2M'(SeO4)2(H2O)6 (selenates). These materials are double salts, which means that they contain two different cations, M+ and M'2+ crystallized in the same regular ionic lattice.

Key takeaways

Tutton's salt belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Tutton's salt to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Tutton's salt from memory before moving on to harder problems.

Reference excerpt

Tutton's salts are a family of salts with the formula M2M'(SO4)2(H2O)6 (sulfates) or M2M'(SeO4)2(H2O)6 (selenates). These materials are double salts, which means that they contain two different cations, M+ and M'2+ crystallized in the same regular ionic lattice. The univalent cation can be potassium, rubidium, caesium, ammonium (NH4), deuterated ammonium (ND4) or thallium. Sodium or lithium ions are too small. The divalent cation can be magnesium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc or cadmium. In addition to sulfate and selenate, the divalent anion can be chromate (CrO42−), tetrafluoroberyllate (BeF42−), hydrogenphosphate (HPO42−) or monofluorophosphate (PO3F2−). Tutton's salts crystallize in the monoclinic space group P21/a. The robustness is the result of the complementary hydrogen-bonding between the tetrahedral anions and cations as well their interactions with the metal aquo complex [M(H2O)6]2+.

Examples and related compounds Perhaps the best-known is Mohr's salt, ferrous ammonium sulfate (NH4)2Fe(SO4)2.(H2O)6). Other examples include the vanadous Tutton salt (NH4)2V(SO4)2(H2O)6 and the chromous Tutton salt (NH4)2Cr(SO4)2(H2O)6. In solids and solutions, the M'2+ ion exists as a metal aquo complex [M'(H2O)6]2+. Related to the Tutton's salts are the alums, which are also double salts but with the formula MM'(SO4)2(H2O)12. The Tutton's salts were once termed "false alums".

History Tutton salts are sometimes called Schönites after the naturally occurring mineral called Schönite (K2Mg(SO4)2(H2O)6). They are named for Alfred Edwin Howard Tutton, who identified and characterised a large range of these salts around 1900. Such salts were of historical importance because they were obtainable in high purity and served as reliable reagents and spectroscopic standards.

Table of salts

Organic salts Some organic bases can also form salts that crystallise like Tutton's salts.

References

Illustrations

Worked examples

Example 1 — a first encounter with Tutton's salt

Start with the simplest possible case. Write down what Tutton's salt claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Tutton's salt 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 Tutton's salt 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 Tutton's salt

In research: Tutton's salt appears in science 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 Tutton's salt 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: Tutton's salt is common in secondary-school and first-year university syllabi. It links to neighbouring topics Double salts, Sulfates, so understanding it makes those chapters shorter.
In everyday life: Look for Tutton's salt 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.

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How to study Tutton's salt in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Tutton's salt means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Tutton's salt out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Tutton's salt in simple terms?

Why does Tutton's salt matter?

Because it connects several science 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 Tutton's salt?

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 Tutton's salt.