chemistry

Tin(IV) oxide

Tin(IV) oxide 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 Tin(IV) oxide rather than just read about it. In short: Tin(IV) oxide, also known as stannic oxide, is the inorganic compound with the formula SnO2. The mineral form of SnO2 is called cassiterite, and this is the main ore of tin.

Key takeaways

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

Reference excerpt

Tin(IV) oxide, also known as stannic oxide, is the inorganic compound with the formula SnO2. The mineral form of SnO2 is called cassiterite, and this is the main ore of tin. With many other names, this oxide of tin is an important material in tin chemistry. It is a colourless, diamagnetic, amphoteric solid.

Structure

Tin(IV) oxide crystallises with the rutile structure. As such the tin atoms are six coordinate and the oxygen atoms three coordinate. SnO2 is usually regarded as an oxygen-deficient n-type semiconductor. Hydrous forms of SnO2 have been described as stannic acid. Such materials appear to be hydrated particles of SnO2 where the composition reflects the particle size.

Preparation Tin(IV) oxide occurs naturally. Synthetic tin(IV) oxide is produced by burning tin metal in air. Annual production is in the range of 10 thousand metric tons (11 thousand short tons). SnO2 is reduced industrially to the metal with carbon in a reverberatory furnace at 1,200–1,300 °C (2,190–2,370 °F).

Reactions The reaction from tin(IV) oxide with hot carbon monoxide is practiced on a large scale as this carbothermal reduction is used to obtain tin metal from its ores:

SnO2 + 2 CO → Sn + 2 CO2 Some other reactions relevant to purifying tin from its ores are:

SnO2 + MgCl2 + CO → SnCl2 + MgO + CO2 4 SnO2 + 6 FeCl2 → 2 SnCl2 + 2 SnCl4 + 2 Fe3O4 SnO2 converts to the monoxide at 1,500 °C (2,730 °F):

2 SnO2 → 2 SnO + O2 SnO2 is insoluble in water. It dissolves in sulfuric acid and in molten sodium hydroxide. It is not amphoteric. Like rutile, it is not attacked by solutions of acid or base. Dissolution of SnO2 in sulfuric acid gives the sulfate:

SnO2 + 2 H2SO4 → Sn(SO4)2 + 2 H2O The latter compound can add additional hydrogen sulfate ligands to give hexahydrogensulfatostannic acid. SnO2 dissolves in molten alkali to give "stannates," with the nominal formula Sodium stannate (Na2SnO3). Dissolving the solidified SnO2/NaOH melt in water gives Na2[Sn(OH)6], "preparing salt," which is used in the dye industry.

Uses In conjunction with vanadium oxide, it is used as a catalyst for the oxidation of aromatic compounds in the synthesis of carboxylic acids and acid anhydrides.

Ceramic glazes SnO2 is used as pigment in the manufacture of glasses, enamels and ceramic glazes. Thousands of tons of SnO2 are produced annually for this application. Pure SnO2 gives a milky white colour; other colours are achieved when mixed with other metallic oxides e.g. vanadium(V) oxide (V2O5) yellow; Chromium(III) oxide (Cr2O3) pink; and antimony pentoxide (Sb2O5) grey blue. This use probably led to the discovery of the pigment lead-tin-yellow, which was produced using tin(IV) oxide as a compound. The use of tin(IV) oxide has been particularly common in glazes for earthenware, sanitaryware and wall tiles; see the articles tin-glazing and Tin-glazed pottery. Tin oxide remains in suspension in vitreous matrix of the fired glazes, and, with its high refractive index being sufficiently different from the matrix, light is scattered, and hence increases the opacity of the glaze. The degree of dissolution increases with the firing temperature, and hence the extent of opacity diminishes. Although dependent on the other constituents the solubility of tin oxide in glaze melts is generally low. Its solubility is increased by Na2O, K2O and B2O3, and reduced by CaO, BaO, ZnO, Al2O3, and to a limited extent PbO.

Glass coatings SnO2 coatings are valued as transparent conducting oxides (TCOs). Like other TCOs, SnO2 has significant electrical conductivity but is transparent, an unusual combination of properties. Windows coated with SnO2 also reflect infrared radiation, which is relevant to temperature control for smart windows. Coatings can be applied using chemical vapor deposition, vapour deposition techniques that employ tin(IV) chloride (SnCl4) or organotin trihalides e.g. butyltin trichloride as the volatile agent. This technique is used to coat glass bottles with a thin (<0.1 μm) layer of SnO2, which helps to adhere a subsequent, protective polymer coating such as polyethylene to the glass. Thicker layers doped with Sb or F ions are electrically conducting and used in electroluminescent devices and photovoltaics.

Gas sensing SnO2 has been evaluated as sensors of combustible gases including carbon monoxide detectors. In these the sensor area is heated to a constant temperature (few hundred °C) and in the presence of a combustible gas the electrical resistivity drops.

Historical uses This oxide of tin has been utilized as a mordant in the dyeing process since ancient Egypt. A German by the name of Kuster first introduced its use to London in 1533 and by means of it alone, the color scarlet was produced there. Tin(IV) oxide for this use is sometimes called "putty powder" or "jeweler's putty".

Polishing Tin(IV) oxide can be used as a polishing powder, sometimes in mixtures also with lead oxide, for polishing glass, jewelry, marble and silver.

References

Illustrations

Worked examples

Example 1 — a first encounter with Tin(IV) oxide

Start with the simplest possible case. Write down what Tin(IV) oxide 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 Tin(IV) oxide 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 Tin(IV) oxide 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 Tin(IV) oxide

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

Read the reference excerpt below once, without taking notes.
Close the page and write down what Tin(IV) oxide 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 Tin(IV) oxide out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Tin(IV) oxide in simple terms?

Tin(IV) oxide, also known as stannic oxide, is the inorganic compound with the formula SnO2. The mineral form of SnO2 is called cassiterite, and this is the main ore of tin.

Why does Tin(IV) oxide 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 Tin(IV) oxide?

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 Tin(IV) oxide.