chemistry

Thorium(IV) nitrate

Thorium(IV) nitrate is a chemistry 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 Thorium(IV) nitrate rather than just read about it. In short: Thorium(IV) nitrate is a chemical compound, a salt of thorium and nitric acid with the formula Th(NO3)4. A white solid in its anhydrous form, it can form tetra- and pentahydrates.

Key takeaways

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

Reference excerpt

Thorium(IV) nitrate is a chemical compound, a salt of thorium and nitric acid with the formula Th(NO3)4. A white solid in its anhydrous form, it can form tetra- and pentahydrates. As a salt of thorium it is weakly radioactive.

Preparation Thorium(IV) nitrate hydrate can be prepared by the reaction of thorium(IV) hydroxide and nitric acid:

Th(OH)4 + 4 HNO3 + 3 H2O → Th(NO3)4 + 5 H2O Different hydrates are produced by crystallizing in different conditions. When a solution is very dilute, the nitrate is hydrolysed. Although various hydrates have been reported over the years, and some suppliers even claim to stock them, only the tetrahydrate and pentahydrate actually exist. What is called a hexahydrate, crystallized from a neutral solution, is probably a basic salt. The pentahydrate is the most common form. It is crystallized from dilute nitric acid solution. The tetrahydrate, Th(NO3)4·4H2O is formed by crystallizing from a stronger nitric acid solution. Concentrations of nitric acid from 4 to 59% result in the tetrahydrate forming. The thorium atom has 12-coordination, with four bidentate nitrate groups and four water molecules attached to each thorium atom. To obtain the anhydrous thorium(IV) nitrate, thermal decomposition of Th(NO3)4·2N2O5 is required. The decomposition occurs at 150–160 °C (302–320 °F).

Properties Anhydrous thorium nitrate is a white substance. It is covalently bound with low melting point of 55 °C (131 °F). The pentahydrate Th(NO3)4·5H2O crystallizes with clear colourless crystals in the orthorhombic system. Each thorium atom is connected twice to each of four bidentate nitrate groups, and to three water molecules via their oxygen atoms. In total the thorium is eleven-coordinated. There are also two other water molecules in the crystal structure.The water is hydrogen bonded to other water, or to nitrate groups. Thorium nitrate can dissolve in several different organic solvents including alcohols, ketones, esters and ethers. This can be used to separate different metals such as the lanthanides. With ammonium nitrate in the aqueous phase, thorium nitrate prefers the organic liquid, and the lanthanides stay with the water. Thorium nitrate dissolved in water lowers it freezing point. The maximum freezing point depression is −37 °C (−35 °F) with a concentration of 2.9 mol/kg.

Reactions

When thorium nitrate pentahydrate is heated, nitrates with less water are produced, however the compounds also lose some nitrate. At 140 °C (284 °F) a basic nitrate, ThO(NO3)2 is produced. When strongly heated thorium dioxide is produced. A polymeric peroxynitrate is precipitated when hydrogen peroxide combines with thorium nitrate in solution with dilute nitric acid. Its formula is Th6(O2)10(NO3)4·10H2O.

The hydrolysis of thorium nitrate solutions produces basic nitrates Th2(OH)4(NO3)4·xH2O and Th2(OH)2(NO3)6·8H2O. In crystals of Th2(OH)2(NO3)6·8H2O a pair of thorium atoms are connected by two bridging oxygen atoms. Each thorium atom is surrounded by three bidentate nitrate groups and three water molecules, bringing the coordination number to 11. When oxalic acid is added to a thorium nitrate solution, insoluble thorium oxalate precipitates. Other organic acids added to thorium nitrate solution produce precipitates of organic salts with citric acid; basic salts, such as tartaric acid, adipic acid, malic acid, gluconic acid, phenylacetic acid, valeric acid. Other precipitates are also formed from sebacic acid and azelaic acid

Double salts Hexanitratothorates with the generic formula M2ITh(NO3)6 or MIITh(NO3)6·8H2O are made by mixing other metal nitrates with thorium nitrate in dilute nitric acid solution. MII can be Mg, Mn, Co, Ni, or Zn. MI can be Cs, (NO)+ or (NO2)+. Crystals of the divalent metal thorium hexanitrate octahydrate have a monoclinic form with similar unit cell dimensions: β=97°, a=9.08 b=8.75-8 c=12.61-3. Pentanitratothorates with the generic formula MITh(NO3)5·xH2O are known for MI being Na or K. K3Th(NO3)7 and K3H3Th(NO3)10·4H2O are also known.

Complexed salts Thorium nitrate also crystallizes with other ligands and organic solvates including ethylene glycol diethyl ether, tri(n-butyl)phosphate, butylamine, dimethylamine, and trimethylphosphine oxide.

References

Notes

Illustrations

Worked examples

Example 1 — a first encounter with Thorium(IV) nitrate

Start with the simplest possible case. Write down what Thorium(IV) nitrate 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 Thorium(IV) nitrate 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 Thorium(IV) nitrate 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 Thorium(IV) nitrate

In research: Thorium(IV) nitrate 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 Thorium(IV) nitrate 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: Thorium(IV) nitrate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Deliquescent materials, Nitrates, Thorium(IV) compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Thorium(IV) nitrate 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 Thorium(IV) nitrate in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Thorium(IV) nitrate 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.
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Frequently asked questions

What is Thorium(IV) nitrate in simple terms?

Thorium(IV) nitrate is a chemical compound, a salt of thorium and nitric acid with the formula Th(NO3)4. A white solid in its anhydrous form, it can form tetra- and pentahydrates.

Why does Thorium(IV) nitrate 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 Thorium(IV) nitrate?

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 Thorium(IV) nitrate.