CodeCogs fxEditor

Chemistry equations, reactions and structures

Write a reaction as you would on paper — formulae, charges, states and arrows — or draw a molecule from the toolbar, and copy it into your notes, worksheet or web page as MathML, SVG or PNG.

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The equations everyone needs

The reactions and formulae that come up again and again, from school to university. Each is drawn here by the same fxTeX the editor uses; Edit this equation puts it in the editor at the top of the page, ready to change and copy.

Photosynthesis

Biology
\ce{6CO2 + 6H2O ->[light] C6H12O6 + 6O2}

Burning methane

Combustion
\ce{CH4 + 2O2 -> CO2 + 2H2O}

The Haber process

Equilibrium
\ce{N2 + 3H2 <=> 2NH3}

Neutralisation

Acids and bases
\ce{HCl + NaOH -> NaCl + H2O}

A precipitate

Ionic
\ce{Ag+ (aq) + Cl- (aq) -> AgCl v}

Alpha decay

Nuclear
\ce{^{238}_{92}U -> ^{234}_{90}Th + ^{4}_{2}He}

The equilibrium constant

Equilibrium
K_c = \frac{[\ce{NH3}]^2}{[\ce{N2}][\ce{H2}]^3}

pH

Acids and bases
\mathrm{pH} = -\log_{10}[\ce{H+}]

The molecules everyone draws

Structures drawn with chemfig: bonds, rings and groups, written as a line of text the editor turns into a picture. Edit this structure puts it in the editor, where the toolbar’s structure editor can change it.

Water

Inorganic
\chemfig{H-[:37.5]O-[:-37.5]H}

Carbon dioxide

Inorganic
\chemfig{O=C=O}

Methane

Alkane
\chemfig{C(-[2]H)(-[4]H)(-[6]H)-H}

Ethanol

Alcohol
\chemfig{H_3C-CH_2-OH}

Ethanoic acid

Carboxylic acid
\chemfig{H_3C-C(=[1]O)-[7]OH}

Benzene

Aromatic
\chemfig{*6(-=-=-=)}

Phenol

Aromatic
\chemfig{*6(-=-=(-OH)-=)}

Aspirin

Medicine
\chemfig{*6(-=-(-O-C(=[2]O)-CH_3)=(-COOH)-=)}

Writing chemistry

Type a reaction as you would say it

Inside \ce{...} the numbers in a formula drop to subscripts and charges rise to superscripts on their own.

  • H2SO4 a formula
  • SO4^2- or Fe^3+ a charge
  • -> <=> arrows; ->[heat] with a condition
  • (aq) (s) v ^ states, a precipitate, a gas

Or draw the molecule

The chemfig panels give rings, chains, double and triple bonds and wedges a click each, and the structure editor draws or changes a molecule with the mouse. The chemfig is written for you.

Then take it where it is going

A reaction goes into Microsoft Word as an equation, or onto a web page as MathML with its spoken text for screen readers. A structure is a picture: download it as an SVG or PNG for slides, worksheets and web pages.

Questions

How do I write a chemical equation online?

Type it inside \ce{...} — \ce{2H2 + O2 -> 2H2O} — or build it from the chemistry panels at the start of the toolbar. Subscripts, charges and arrows are set for you, and the result copies out as MathML, SVG or PNG.

Can I draw a molecule’s structure?

Yes. The chemfig panels have rings, bonds and groups, and the structure editor on the toolbar draws a molecule with the mouse. The structure is kept as chemfig, so it can be changed later.

How do I get a chemical equation into Word or Google Docs?

For Word, copy it as MathML and paste. For Google Docs, or anywhere that takes a picture, download it as a PNG or SVG. Structures come out best as pictures.

Is it free?

Yes, for non-commercial use: study, teaching, research, or a personal site. Equations made as part of work you sell — a book, a course, a product — need a licence. How licensing works.

Try it on the real thing

The full editor is on the home page, with suggestions as you type, history and every export format. It is free for non-commercial use — study, teaching, research or a personal site. Building it into something you sell needs a commercial licence.

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