chemistry

Germane

Germane 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 Germane rather than just read about it. In short: Germane is the chemical compound with the formula GeH4, and the germanium analogue of methane. It is the simplest germanium hydride and one of the most useful compounds of germanium.

Key takeaways

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

Reference excerpt

Germane is the chemical compound with the formula GeH4, and the germanium analogue of methane. It is the simplest germanium hydride and one of the most useful compounds of germanium. Like the related compounds silane and methane, germane is tetrahedral. It burns in air to produce GeO2 and water. Germane is a group 14 hydride.

Occurrence Germane has been detected in the atmosphere of Jupiter.

Synthesis Germane is typically prepared by reduction of germanium oxides, notably germanates, with hydride reagents such as sodium borohydride, potassium borohydride, lithium borohydride, lithium aluminium hydride, sodium aluminium hydride. The reaction with borohydrides is catalyzed by various acids and can be carried out in either aqueous or organic solvent. On laboratory scale, germane can be prepared by the reaction of Ge(IV) compounds with these hydride reagents. A typical synthesis involved the reaction of potassium hydrogen germanate with potassium borohydride.

K+HGeO−3 + K+[BH4]− + H2O → KGeH3 + K+[B(OH)4]− KGeH3 + CH3COOH → GeH4 + CH3COO−K+ Other methods for the synthesis of germane include electrochemical reduction and a plasma-based method. The electrochemical reduction method involves applying voltage to a germanium metal cathode immersed in an aqueous electrolyte solution and an anode counter-electrode composed of a metal such as molybdenum or cadmium. In this method, germane and hydrogen gases evolve from the cathode while the anode reacts to form solid molybdenum oxide or cadmium oxides. The plasma synthesis method involves bombarding germanium metal with hydrogen atoms (H) that are generated using a high frequency plasma source to produce germane and digermane.

Reactions Germane is weakly acidic. In liquid ammonia GeH4 is ionised forming NH4+ and GeH3−. With alkali metals in liquid ammonia GeH4 reacts to give white crystalline MGeH3 compounds. The potassium (potassium germyl or potassium trihydrogen germanide KGeH3) and rubidium compounds (rubidium germyl or rubidium trihydrogen germanide RbGeH3) have the sodium chloride structure implying a free rotation of the trihydrogen germanide anion GeH3−, the caesium compound, caesium germyl or caesium trihydrogen germanide CsGeH3 in contrast has the distorted sodium chloride structure of TlI.

Use in semiconductor industry The gas decomposes near 600K (327°C; 620°F) to germanium and hydrogen. Because of its thermal lability, germane is used in the semiconductor industry for the epitaxial growth of germanium by MOVPE or chemical beam epitaxy. Organogermanium precursors (e.g. isobutylgermane, alkylgermanium trichlorides, and dimethylaminogermanium trichloride) have been examined as less hazardous liquid alternatives to germane for deposition of Ge-containing films by MOVPE.

Safety Germane is a highly flammable, potentially pyrophoric, and a highly toxic gas. In 1970, the American Conference of Governmental Industrial Hygienists (ACGIH) published the latest changes and set the occupational exposure threshold limit value at 0.2 ppm for an 8-hour time weighted average. The LC50 for rats at 1 hour of exposure is 622 ppm. Inhalation or exposure may result in malaise, headache, dizziness, fainting, dyspnea, nausea, vomiting, kidney injury, and hemolytic effects. The US Department of Transportation hazard class is 2.3 Poisonous Gas.

References

External links

Metaloids (manufacturer) datasheet Arkonic Specialty Gases China (manufacturer) datasheet Licensintorg Russia (process technology sale) Archived 2013-03-29 at the Wayback Machine Honjo Chemical Japan (manufacturer) Archived 2013-01-20 at the Wayback Machine Praxair datasheet Air liquide gas encyclopedia entry Archived 2013-07-30 at the Wayback Machine CDC - NIOSH Pocket Guide to Chemical Hazards Voltaix (manufacturer) datasheet Archived 2011-07-17 at the Wayback Machine Foshan Huate Gas Co., Ltd. (manufacturer) Horst Technologies, Russia (manufacturer)

Illustrations

Worked examples

Example 1 — a first encounter with Germane

Start with the simplest possible case. Write down what Germane 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 Germane 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 Germane 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 Germane

In research: Germane 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 Germane 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: Germane is common in secondary-school and first-year university syllabi. It links to neighbouring topics Germanium(IV) compounds, Industrial gases, Metal hydrides, so understanding it makes those chapters shorter.
In everyday life: Look for Germane 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 Germane in 20 minutes

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

Frequently asked questions

What is Germane in simple terms?

Germane is the chemical compound with the formula GeH4, and the germanium analogue of methane. It is the simplest germanium hydride and one of the most useful compounds of germanium.

Why does Germane 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 Germane?

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 Germane.