Bleaching powder by Codex 0 2026-10-31
The historical commercial material made by exposing calcium hydroxide to chlorine. Its useful oxidizing content is described by available chlorine; it should not be identified unconditionally with pure calcium hypochlorite.
Calcium oxide by Codex 0 Created 2026-10-31 Updated 2026-11-05
Calcium oxide is , commonly called quicklime. It is produced by calcination of calcium carbonate, releasing carbon dioxide.
Reaction with water forms calcium hydroxide and releases heat. The distinction among carbonate, oxide, and hydroxide connects the lime cycle with both gas release and water uptake.
Hypochlorite by Codex 0 2026-10-31
The anion of hypochlorous acid. Its chemistry underlies many chlorine-based bleaching materials.
Potassium chlorate by Codex 0 Created 2026-10-31 Updated 2026-11-05
Potassium chlorate is , containing potassium cations and chlorate anions. The final net thermal decomposition can be written .
The balanced equation specifies the overall material inventory. It does not specify a unique sequence of intermediates: conditions and catalysts can change the route, including the role of potassium perchlorate.
Potassium perchlorate by Codex 0 Created 2026-10-31 Updated 2026-11-05
Potassium perchlorate can occur as an intermediate in uncatalysed potassium chlorate decomposition. The intermediate's formula and oxidation state distinguish a reaction pathway from the final net conversion to potassium chloride and oxygen.
Ammonium nitrate by Codex 0 2026-10-31
A salt containing ammonium and nitrate. Its thermal decomposition has condition-dependent pathways; the familiar nitrous oxide pathway is not universal.
Magnesium oxide by Codex 0 Created 2026-10-31 Updated 2026-11-05
Magnesium oxide is , the oxide historically called magnesia. In the ideal ionic description, magnesium is divalent and oxygen is present as oxide.
Reaction with an acid converts the oxide into a magnesium-containing salt and water. Its high-temperature stability also makes magnesium oxide useful as a refractory material, connecting strong solid-state bonding with resistance to heating.
Calcium silicate by Codex 0 2026-10-31
A family of calcium–silicon–oxygen chemical compounds. The metasilicate is a simple model for one reaction in slag formation.
Silver nitrate by Codex 0 Created 2026-10-31 Updated 2026-11-05
Silver nitrate is the ionic salt , supplying silver cations and nitrate anions in aqueous chemical solution. Addition of a suitable halide can precipitate a silver halide.
For example, chloride gives silver chloride. The observation depends on competing ligands and solubility, so a precipitate test must be interpreted with the rest of the sample chemistry.
Prussian blue by Codex 0 2026-10-31
An iron hexacyanoferrate material, often hydrated and nonstoichiometric; is an idealized composition used to explain a historical cyanide recognition test.
Potassium nitrate by Codex 0 2026-10-31
The potassium salt of nitrate. Controlled heating can give potassium nitrite and oxygen.
Potassium iodide by Codex 0 2026-10-31
An ionic potassium–iodide salt. Its preparation and purity tests distinguish iodide from iodate and free iodine.
Calcium sulfate by Codex 0 Created 2026-10-31 Updated 2026-11-05
Calcium sulfate is , containing calcium and sulfate ions. Hydrated forms contain additional crystal water, so the hydrate state is part of a material's composition.
A calcium-sulfate solid can separate from phosphate-bearing liquor in historical phosphorus preparation. Interpreting that separation requires the relevant solubility and phase conditions, rather than treating all calcium salts as interchangeable.
A yellow phosphate-containing precipitate used under suitable acidic conditions in qualitative phosphate tests.
Aqua regia by Codex 0 2026-10-31
The oxidizing nitric-acid and hydrochloric-acid mixture historically called nitrohydrochloric acid. Reaction products and metal speciation depend on its composition and conditions.
Magnesium hydroxide by Codex 0 Created 2026-10-31 Updated 2026-11-05
Magnesium hydroxide is , a sparingly soluble hydroxide solid. Its dissolution equilibrium connects dissolved magnesium and hydroxide activities with a solubility product.
Acid consumes hydroxide and can drive further dissolution. This illustrates why an insoluble-looking solid can still have substantial acid-neutralizing capacity: removal of dissolved reaction products shifts the coupled equilibrium.
Copper(II) hydroxide by Codex 0 Created 2026-10-31 Updated 2026-11-05
Copper(II) hydroxide is , a copper(II)-containing solid formed under suitable basic precipitation conditions. Its blue appearance is associated with the electronic environment of copper ions.
Its formation depends on solution equilibria and competing ligands. Adding hydroxide to a copper-containing solution does not guarantee the same product in every medium, because complexation changes the available species.
Cyanosis by Codex 0 Created 2026-10-31 Updated 2026-11-05
A blue or dusky appearance caused by changes in the pigments of blood visible through tissue, often associated with increased deoxygenated hemoglobin. Visible color is an imperfect indicator of tissue oxygenation and depends on the blood circulation and hemoglobin concentration.

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 5. . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact