Nitratine

Key takeaways

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

Reference excerpt

Nitratine or nitratite, also known as cubic niter (UK: nitre), soda niter or Chile saltpeter (UK: Chile saltpetre), is a mineral, the naturally occurring form of sodium nitrate, NaNO3. Chemically it is the sodium analogue of saltpeter. Nitratine crystallizes in the trigonal system, but rarely occurs as well-formed crystals. It is isostructural with calcite. It is relatively soft and light with a Mohs hardness of 1.5 to 2 and a specific gravity of 2.24 to 2.29. Its refractive indices are nω = 1.587 and nε = 1.336. The typical form is as coatings of white, grey to yellowish brown masses. The rare crystals when found typically have the scalenohedral form of the calcite structure. It is found only as an efflorescence in very dry environments. It is very soluble in water such that it is deliquescent and will absorb water out of the air and turn into a puddle of sodium nitrate solution when exposed to humid air. There are nitratine deposits located in arid regions across the world such as in Chile, Mexico, Egypt, Peru, and South Africa. Chile is the only country to sell their deposits commercially as fertilizer. The salt bed that is mined contains more minerals than just nitratine often containing sulfurous minerals as well as Iodine. Around 600,000 tons of nitratine are mined in Chile each year with other products such as Iodine and sodium sulfate mined as well. Nitratine happens to be isostructural to calcite, CaCO3, a widespread naturally occurring mineral, although nitratine dissolution and crystallization occur much faster than the same processes for calcite. The structural similarity makes nitratine a very useful mineral for laboratory experiments concerning pressure dissolution and other experiments such as serving as a proxy for the deformation and formation of calcite. The Saltpeter War (1480–1510) and the War of the Pacific (1879–1884) were fought over the control of saltpeter deposits.

Uses Nitratine was once an important source of nitrates for fertilizer and other chemical uses including fireworks. It has been known since 1845 from mineral deposits in the Confidence Hills, Southern Death Valley, California and the Atacama Desert, Chile. It is still used in organic farming (where Haber–Bosch ammonia is forbidden) in the US, but prohibited in international organic agriculture. The mineral also has a wide range of applications beyond being used as a fertilizer in agricultural practices. Nitratine has been used in the explosives industry for water-containing slurry as well as gel explosives. It is also used as a refining agent to remove air bubbles by the glass and enamel industries. Nitratine, other alkali nitrates, or nitrites also have applications for solar technology serving as a heat-transfer or heat-storage medium. Nitratine can also be used as a substitute for potassium nitrate in gunpowder.

Synthetic sodium nitrate After World War I the need for a more efficient production of fertilizer led to the production of synthetic nitratine which was much less costly in terms of production than the Shanks process used to refine chilean saltpeter. The method of production involved using tail gases from nitric acid plants in combination with sodium carbonate solution or sodium hydroxide solution. Through a series of reactions it is possible to produce sodium nitrate and sodium nitrate with byproducts such as nitrogen monoxide and water. The following reactions show the chemistry necessary to produce sodium nitrates:

2 NaOH + 2 NO 2 + NO ⟶ 2 NaNO 2 + H 2 O {\displaystyle {\ce {2NaOH + 2NO2 + NO -> 2NaNO2 + H2O}}}

Na 2 CO 3 + NO 2 + NO ⟶ 2 NaNO 2 + CO 2 {\displaystyle {\ce {Na2CO3 + NO2 + NO -> 2NaNO2 +CO2}}}

2 NaOH + 2 NO 2 ⟶ NaNO 3 + NaNO 2 + H 2 O {\displaystyle {\ce {2NaOH + 2NO2 -> NaNO3 + NaNO2 + H2O}}}

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Nitratine

Start with the simplest possible case. Write down what Nitratine claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth 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 Nitratine 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 Nitratine 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 Nitratine

In research: Nitratine appears in earth 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 Nitratine 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: Nitratine is common in secondary-school and first-year university syllabi. It links to neighbouring topics Mineral stubs, Minerals in space group 167, Nitrate minerals, so understanding it makes those chapters shorter.
In everyday life: Look for Nitratine 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 Nitratine in 20 minutes

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

Frequently asked questions

What is Nitratine in simple terms?

Nitratine or nitratite, also known as cubic niter (UK: nitre), soda niter or Chile saltpeter (UK: Chile saltpetre), is a mineral, the naturally occurring form of sodium nitrate, NaNO3. Chemically it is the sodium analogue of saltpeter.

Why does Nitratine matter?

Because it connects several earth 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 Nitratine?

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 Nitratine.